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HVAC System - Automatic - Seville Cadillac Seville V

Automatic HVAC System 15 illustrations ~27011 words

SPECIFICATIONS

ApplicationSpecification
Compressor TypeSanden Scroll
Compressor Belt Tension(1)
System Oil Capacity (2)8.8 ozs.
Refrigerant (R-134a) Capacity
2000 Models32.1 ozs.
2001 Models35.2 ozs.
System Operating Pressures (3)
High Side129-159 psi (9.1-11.2 kg/cm 2 )
Low Side35-41 psi (2.5-2.9 kg/cm 2 )
(1) Belt tension is maintained automatically by belt tensioner. (2) Use PAG Oil (Polyalkylene Glycol). (3) Approximate operating pressures with relative humidity more than 40 percent, ambient temperature at 70°F (21°C) and engine at idle. Maximum left center discharge air temperature is 56°F (13°C).
(1)Belt tension is maintained automatically by belt tensioner.
(2)Use PAG Oil (Polyalkylene Glycol).
(3)Approximate operating pressures with relative humidity more than 40 percent, ambient temperature at 70°F (21°C) and engine at idle. Maximum left center discharge air temperature is 56°F (13°C).

SPECIFICATIONS

DESCRIPTION

WARNINGTo avoid injury from accidental air bag deployment, read and carefully follow all SERVICE PRECAUTIONS and DISABLING & ACTIVATING AIR BAG SYSTEM procedures in AIR BAG SYSTEM SAFETY article in GENERAL SERVICING.

The Heating, Ventilation and Air Conditioning (HVAC) system automatically regulates and maintains selected in-vehicle temperature between 65°F (18°C) and 85°F (29°C) regardless of changes in outside air temperature. Settings of 60°F (16°C) and 90°F (32°C) provide unregulated cooling and heating, respectively.

Main components of HVAC system are Instrument Panel Integration Module (IPM), Powertrain Control Module (PCM), refrigerant system, temperature sensors, and HVAC module. IPM is the main control for selecting in-vehicle comfort levels.

Dual Zone automatic A/C-heater system allows driver and passenger to adjust outlet temperatures separately. Driver controlled operations include mode, compressor clutch operation, blower motor operation and outlet temperature. When set to fully automatic dual zone mode, driver has same control functions, with addition of passenger control functions to increase or decrease passenger side outlet temperature. Rear seat passengers have control of a separate rear blower motor and outlet settings.

HVAC CONTROL PANEL

HVAC control panel contains Instrument Panel Integration Module (IPM). HVAC control panel allows operator to communicate with IPM to obtain desired settings. Functions of HVAC control panel include blower motor speed, mode operation, driver and passenger temperature settings, and air intake control. (Scheme 1)

TEMP Knob (Driver's Side)

Driver's side temperature knob adjusts air temperature coming through system. HVAC system or driver's side temperature will increase when knob is turned clockwise and decrease when knob is turned counterclockwise. Temperature can be adjusted from 60°F (16°C) to 90°F (32°C). When TEMP knob is pressed HVAC system can be turned off or on. If system is off, pressing any button on control panel will turn HVAC system on. When system is turned off, fresh air will continue to flow through vehicle. System will attempt to maintain selected temperature by regulating air mix valve. Because blower motor and A/C compressor do not operate, set temperature will probably not be reached. When in OFF mode, HVAC control panel will display only outside temperature. (Scheme 1)

TEMP Knob (Passenger's Side)

Passenger's side temperature knob adjusts air temperature for front and rear passengers. Temperature will increase when knob is turned clockwise and decrease when knob is turned counterclockwise. Temperature can be adjusted from 60°F (16°C) to 90°F (32°C) independent of driver's side. For optimum results, passenger's side temperature should not be adjusted more than 4°F (2°C) warmer or cooler than driver's side. When TEMP knob is pressed, passenger's side HVAC system can be turned off or on. When passenger's side is off, driver's side knob controls vehicle temperature. (Scheme 1)

AUTO Button

When AUTO mode is selected, HVAC system, including compressor operation, is controlled automatically by various inputs to adjust to selected temperature. System can use any blower speed, any air inlet position, and any air outlet position to reach selected temperature. Depending on heating or cooling requirement, air will enter passenger compartment from bi-level registers and vents, upper registers only, or lower vents only. (Scheme 1)

MODE Button

Mode button is used to manually select air discharge location. Operator can select from 4 different modes: defog, floor (lower), floor/defrost (bi-level), and panel (upper). Press left or right arrow to cycle through available modes. (Scheme 1) HVAC system will stay in selected mode until MODE button, DEFROST button or AUTO button is pressed.

Defog Mode

In this mode, air is divided equally between floor and defroster vents. Compressor is turned on at temperatures more than 40°F (4°C) to dehumidify passenger compartment air.

Heater Mode

Directs warmed air to floor outlets. A small amount of air is diverted to windshield to minimize fogging.

Upper Mode

Directs airflow through middle instrument panel outlets and driver's side lap cooler.

Bi-Level Mode

Directs cool air from 4 instrument panel vents and warmed air to floor outlets.

FRONT (Defrost) Button

In this mode, all functions are controlled automatically. When FRONT button is pressed, LED illuminates. Compressor is turned on at temperatures more than 40°F (4°C). Outside air is cooled, dehumidified, heated, and delivered to windshield with small amount exiting from floor vents. (Scheme 1)

A/C Button

Pressing A/C button turns A/C compressor on and off. When A/C button is pressed, A/C OFF is displayed on HVAC control panel display. When pressed again, HVAC system will return to automatic mode if ambient temperatures are more than 40°F (4°C). HVAC system will keep evaporator core at constant temperature of 38°F (3°C). Pressing A/C button a second time will turn off A/C compressor.

RECIRC Button

In this mode, inside air is recirculated through HVAC module. RECIRC mode is not available during DEFROST or DEFOG mode. In AUTO mode, HVAC system may use air recirculation as necessary to cool air. Manual RECIRC mode is canceled when any other mode is selected or ignition switch is cycled off. (Scheme 1)

Dual Zone Mode (With Dual Zone A/C-Heater System)

In this mode, operation is similar to AUTO mode, except that air mix door is split and each side has its own actuator. Instrument panel integration module operates each actuator separately, according to control panel and passenger temperature control knob settings. When system is operating in any mode except dual zone mode, actuators operate in unison.

Blower Speed Selector Button

When AUTO button is selected, blower speeds are controlled automatically based on various system inputs. If up arrow on blower speed selector button is pressed once, blower speed increases slightly and control panel displays HI AUTO. (Scheme 1) Blower is still automatically controlled, but at slightly faster speeds. If up arrow is pressed twice, blower runs at a fixed high speed and control panel displays HI. This overrides automatic control. If down arrow is pressed once, blower speed decreases slightly and control panel displays AUTO LO. Blower is still automatically controlled, but at slightly slower speeds. If down arrow is pressed twice, blower runs at a fixed low speed and control panel displays LO. This overrides automatic control.

Scheme 1

Scheme 1: Blower Speed Selector Button
Scheme 1: Blower Speed Selector Button

AUXILIARY BLOWER/MODE CONTROL PANEL

The auxiliary blower motor/mode control, located at rear of console, is manually controlled. A switch with 4 positions (low, medium, medium-high, and high) is used to control blower motor speed. Mode operation can be selected using knob and positioning to desired outlet. Auxiliary system is also turned off with mode knob. (Scheme 2) IPM monitors blower speed feedback for diagnosis.

Scheme 2

Scheme 2: AUXILIARY BLOWER/MODE CONTROL PANEL
Scheme 2: AUXILIARY BLOWER/MODE CONTROL PANEL

STEERING WHEEL CONTROLS

Operation of HVAC system can be controlled by rocker switches located on steering wheel. Blower motor speed and temperature for main system can be set using these switches.

TEMPERATURE SETTINGS

Temperature settings range from 60°F (16°C) to 90°F (32°C). Turning temperature control knob in either direction or pressing COOL or WARM button once will decrease or increase set temperature by one degree Fahrenheit. If button is held continuously, set temperature will continue to decrease or increase until limit of 65°F (18°C) or 85°F (29°C) is reached.

Once setting reaches 65°F (18°C), next lowest available temperature setting is 60°F (16°C), representing maximum cooling. At 85°F (29°C) setting, next highest available temperature setting is 90°F (32°C), representing maximum heating. Selected temperature will be displayed on HVAC control panel display.

When an increase or decrease of set temperature occurs, IPM will change blower speed, air discharge location, and temperature to bring in-vehicle temperature to set temperature.

HVAC MODULE

Heating, Ventilation, and Air Conditioning (HVAC) module incorporates many A/C components into one assembly. Function of air delivery system is to distribute airflow throughout vehicle. Major components of HVAC module include air inlet valve, blower motor, evaporator core, air mix valve, heater core, up-down valve, and A/C-defrost valve. (Scheme 3)

Scheme 3

Scheme 3: HVAC MODULE
Scheme 3: HVAC MODULE

AUXILIARY BLOWER/MODE ASSEMBLY

Auxiliary air delivery to rear seat occupants is independently controlled manually and has a dedicated blower motor/mode operation assembly. (Scheme 4) Included in auxiliary blower/mode assembly are blower motor, mode actuator, rear air distributor, rear outlet ducts, and rear blower resistor module. Temperature control is not adjustable through auxiliary blower/mode control panel. (Scheme 2)

Scheme 4

Scheme 4: AUXILIARY BLOWER/MODE ASSEMBLY
Scheme 4: AUXILIARY BLOWER/MODE ASSEMBLY

INSTRUMENT PANEL INTEGRATION MODULE

Contained within HVAC control panel, Instrument Panel Integration Module (IPM) is used to control operation of HVAC system. IPM allows operator selected functions from HVAC control panel to be communicated. All actuators in system are electronically controlled and provide a feedback signal to indicate valve position. Actuators controlled electronically by IPM include driver's air mix, passenger's air mix, mode control, and air inlet. IPM is equipped with a self-diagnostic function. PCM and IPM monitor operating conditions for possible system malfunctions. If a fault is detected, a DTC will be set in memory.

DASH INTEGRATION MODULE

Dash Integration Module (DIM) is located behind glove box, attached to bracket next to right end of HVAC module assembly. DIM monitors A/C pressure, low-side temperature, engine coolant temperature, and battery voltage to check conditions for proper compressor operation. If conditions are within parameters, DIM then sends class 2 serial data signal to PCM through ground circuit and energizes compressor clutch.

TEMPERATURE SENSOR INPUTS

The IPM monitors 2 temperature sensor inputs and 2 solar inputs. DIM monitors 3 temperature inputs.

In-Vehicle Temperature Sensor

This sensor is located in instrument panel to left of center. To provide accurate in-vehicle temperature, air is drawn over sensor by an aspirator.

Outside (Ambient) Temperature Sensor

This sensor is located in front of radiator. A temperature memory is used to provide greater accuracy under engine restart conditions. Signals from this sensor are processed by IPM and displayed on HVAC control center.

Coolant Temperature Sensor

The coolant temperature sensor is located in a coolant passage of intake manifold. Sensor's output is monitored by DIM, which in turn sends a class 2 signal to PCM for compressor operation.

A/C High-Side Temperature Sensor

High-side temperature sensor is located in high-pressure refrigerant line between condenser and orifice tube. Sensor information is used by PCM and DIM in conjunction with coolant temperature to control cooling fan and A/C compressor operation.

A/C Low-Side Temperature Sensor

Low-side temperature sensor is located in low-pressure refrigerant line between orifice tube and evaporator. With sensor information, DIM can determine low-side pressure based on pressure-temperature relation of refrigerant.

Sun Load Sensors

Sun load sensors are located under center defroster grille, at base of windshield. These sensors use light sensitive photocells to measure amount of sunlight on driver's side and on passenger's side of vehicle. Sensor voltage is lowest in direct sunlight and highest when shaded. IPM processes this signal together with temperature signals to determine cooling necessary for maintaining selected interior temperature.

A/C Temperature Sensors

Sensors are located under instrument panel upper trim pad in A/C ducts. Driver and passenger have individual sensors to monitor A/C discharge temperature to help IPM maintain selected in-vehicle A/C discharge temperatures.

Heater Temperature Sensors

These sensors are located in heater outlet ducts. Passenger and driver sides have individual sensors. IPM monitors these signals to help maintain selected discharge temperatures.

A/C PRESSURE SENSOR

Sensor is located in suction hose near A/C compressor. Pressure sensor output to PCM is dependent upon line pressure. High A/C line pressure will increase voltage from sensor to PCM. Compressor clutch is disengaged when line pressure is more than 430 psi (30.2 kg/cm 2 ) or less than 30 psi (2.1 kg/cm 2 ). PCM monitors A/C pressure sensor and will increase engine idle speed to compensate for A/C load. DIM will allow compressor operation when high side pressure decreases to 200 psi (14.1 kg/cm 2 ) and low side pressures rise to 33 psi (2.3 kg/cm 2 ).

ACTUATORS

HVAC system includes 4 actuators to control driver's air mix door, passenger's air mix door, mode door, and air inlet door. These actuators are electronically-controlled reversible DC motors and contain feedback potentiometers to inform IPM of actuator position.

HVAC AIR FILTERS

HVAC filters are located in HVAC module in front of evaporator core. All air entering or being recirculated in vehicle through HVAC module, pass through these filters. Filters consist of 3 separate identical filter elements interlocking to ease in removal and installation for servicing. In addition to filtering out dust particles, filters also help in eliminating unwanted odors from entering passenger compartment. Filters are recommended to be changed once a year.

TROUBLE SHOOTING

WARNINGTo avoid injury from accidental air bag deployment, read and carefully follow all SERVICE PRECAUTIONS and DISABLING & ACTIVATING AIR BAG SYSTEM procedures in AIR BAG SYSTEM SAFETY article in GENERAL SERVICING.

HVAC DIAGNOSTIC SYSTEM CHECK

The Diagnostic System Check will provide the identification of the control module(s) which command the system. The use of the Diagnostic System Check will identify the correct procedure for diagnosing the system and where the procedure is located.

Test Description (2000)

Note. The numbered items here are descriptions of the step number(s) under TESTING (2000)

  1. 2) Lack of communication may be due to a partial malfunction of the class 2 serial data circuit or due to a total malfunction of the class 2 serial data circuit. The specified procedure will determine the particular condition.
  2. 3) The symptom will determine the correct diagnostic procedure to use. See «SYMPTOM TESTS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) .
  3. 4) The presence of DTCs which begin with "U" indicate some other module is not communicating. The specified procedure will compile all the available information before tests are performed.

Testing (2000)

  1. Install scan tool. Does the scan tool power up? If so, go to next step. If not, go to SCAN TOOL DOES NOT POWER UP in BODY CONTROL MODULES - SEVILLE article.
  2. Attempt to establish communication with the following modules: Instrument Panel Module, Powertrain Control Module, Dash Integration Module and Driver Door Module (if equipped with passenger HVAC control). Does the scan tool communicate with the modules? If so, go to next step. If not, go to «SCAN TOOL DOES NOT COMMUNICATE WITH CLASS 2 DEVICE»(ref-8706-S35163793522000091400000) in BODY CONTROL MODULES - SEVILLE article in ACCESSORIES & EQUIPMENT.
  3. Select the display DTC function on the scan tool for the following modules: Instrument Panel Module, Powertrain Control Module, Dash Integration Module and Driver Door Module (if equipped with passenger HVAC control). Does the scan tool display any DTCs? If so, go to next step. If not, go to appropriate symptom under this heading.
  4. Does the scan tool display any DTCs which begin with a "U"? If so, go to «SCAN TOOL DOES NOT COMMUNICATE WITH CLASS 2 DEVICE»(ref-8706-S35163793522000091400000) in BODY CONTROL MODULES - SEVILLE article in ACCESSORIES & EQUIPMENT. If not, go to next step.
  5. Does the scan tool display DTC B1000 for the instrument panel module? If so, go to «DTC B1000: ECU MALFUNCTION»(ref-8706-S26445191122000091400000) under DIAGNOSTIC TESTS in BODY CONTROL MODULES - SEVILLE article in ACCESSORIES & EQUIPMENT. If not, go to next step.
  6. Does the scan tool display DTC B1327 or B1328? If so, go those DTCs under «DIAGNOSTIC TESTS»(ref-8706-S12179773052000091400000) in BODY CONTROL MODULES - SEVILLE article in ACCESSORIES & EQUIPMENT. If not, go to next step.
  7. Does the scan tool display DTC B1004, B1007or B1009? If so, go those DTCs under «DIAGNOSTIC TESTS»(ref-8706-S12179773052000091400000) in BODY CONTROL MODULES - SEVILLE article in ACCESSORIES & EQUIPMENT. If not, go to next step.
  8. Does the scan tool display DTC P0601, P0602, P0604, P0606, or any other codes that would inhibit A/C operation? If so, go to appropriate DTCs under «DIAGNOSTIC TESTS»(ref-4128-S14877193902000061300000) in SELF-DIAGNOSTICS - GASOLINE - 4.6L "E" & "K" BODIES article in ENGINE PERFORMANCE.

Test Description (2001)

Note. The numbered items here are descriptions of the step number(s) under TESTING (2001).

  1. 3) Lack of communication may be due to a partial malfunction of the class 2 serial data circuit or due to a total malfunction of the class 2 serial data circuit. The specified procedure will determine the particular condition.
  2. 4) Determine if the Powertrain Control Module, Instrument Panel Module, Dash Integration Module or Rear Integration Module have set DTC's which may affect HVAC operation when present.
  3. 5) The presence of DTCs which begin with "U" indicate some other module is not communicating. The specified procedure will compile all the available information before tests are performed.
  4. 6) Answer YES if the first 3 characters of the DTC name begins with B10; regardless of the last 2 characters.

Testing (2001)

The Diagnostic System Check will provide the identification of the control module(s) which command the system. The use of the Diagnostic System Check will identify the correct procedure for diagnosing the system and where the procedure is located.

  1. Install a scan tool. Does the scan tool power up? If so. go to next step. If not, go to SCAN TOOL DOES NOT POWER UP under SYSTEM TESTS in BODY CONTROL MODULES - SEVILLE article.
  2. Important The engine may start during this step. Turn OFF the engine as soon as you have observed the crank power mode. Access the CLASS 2 POWER MODE in the DIAGNOSTIC CIRCUIT CHECK on the scan tool. Rotate the ignition switch through all positions while observing the ignition switch power mode parameter. Does the ignition switch parameter reading match the ignition switch position for all switch positions? If so, go to next step. If not, go to POWER MODE MISMATCH under SYSTEM TESTS in BODY CONTROL MODULES - SEVILLE article in ACCESSORIES & EQUIPMENT.
  3. Turn ON the ignition, with the engine OFF. Attempt to establish communication with the following control modules: Powertrain Control Module, Instrument Panel Module, Dash Integration Module and Rear Integration Module. Does the scan tool communicate with the control modules? If so, go to next step. If not, go to SCAN TOOL DOES NOT COMMUNICATE WITH CLASS 2 DEVICE under SYSTEM TESTS in BODY CONTROL MODULES - SEVILLE article in ACCESSORIES & EQUIPMENT.
  4. Select the display DTC function on the scan tool for the following modules: Instrument Panel Module, Powertrain Control Module and Dash Integration Module. Does the scan tool display any DTCs? If so, go to next step. If not, go to appropriate symptom under «SYMPTOM TESTS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) .
  5. Does the scan tool display any DTCs which begin with a "U"? If so, go to SCAN TOOL DOES NOT COMMUNICATE WITH CLASS 2 DEVICE under SYSTEM TESTS in BODY CONTROL MODULES - SEVILLE article in ACCESSORIES & EQUIPMENT. If not, go to next step.
  6. Does the scan tool display DTC B10XX or B1658? If so, go to appropriate DTCs under DIAGNOSTIC TESTS in BODY CONTROL MODULES - SEVILLE article in ACCESSORIES & EQUIPMENT. If not, go to next step.
  7. Does the scan tool display any charging system DTCs (B1327 or B1328)? If so, perform appropriate test. See appropriate GENERATORS & REGULATORS article in STARTING & CHARGING SYSTEMS. If not, go to next step.
  8. Does the scan tool display any HVAC related DTCs? See «HVAC DIAGNOSTIC TROUBLE CODE DEFINITIONS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) table under SELF DIAGNOSTICS. If so, perform appropriate test under «DIAGNOSTIC TESTS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . If not, does scan tool display other DTCs? If so, go to appropriate DTCs under «DIAGNOSTIC TESTS»(/cadillac/seville/v-1998-2004/remont/testing-diagnostics/#engine-control-system-self-diagnostics-46l__diagnostic-tests) in SELF-DIAGNOSTICS - 4.6L DEVILLE, ELDORADO & SEVILLE article in ENGINE PERFORMANCE.

HVAC BLOWER CONTROLS SYSTEM CHECK

  1. Start engine. Place gear selector lever in park. Adjust blower speed with HVAC control panel. Blower speed should vary according to control assembly. For abnormal results, see appropriate procedure in «TROUBLE SHOOTING»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville__trouble-shooting) .
  2. Adjust auxiliary blower speed with auxiliary blower switch in rear of center console. Auxiliary blower speed should vary according to blower switch. For abnormal results, see appropriate procedure in «TROUBLE SHOOTING»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville__trouble-shooting) .

HVAC COMPRESSOR CONTROLS SYSTEM CHECK

  1. Start engine. Place gear selector lever in park. Set HVAC control panel to 60°F (16°C). A/C compressor clutch should engage and cold air should flow from selected outlets. If compressor clutch does not engage, see appropriate procedure in «TROUBLE SHOOTING»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville__trouble-shooting) . If air from outlets does not get cold, see REFRIGERANT SYSTEM DIAGNOSIS in MANUAL A/C-HEATER SYSTEMS - TROUBLE SHOOTING article.
  2. Turn A/C off. Compressor clutch should disengage and air should no longer flow from outlets. If compressor clutch does not disengage, see appropriate procedure in «TROUBLE SHOOTING»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville__trouble-shooting) .

HVAC AIR DELIVERY SYSTEM CHECK

  1. Start engine. Place gear selector lever in park. Adjust air delivery location with HVAC control panel. Air discharge from outlets should correspond with selections on control assembly. If air delivery is not correct, see appropriate procedure in «TROUBLE SHOOTING»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville__trouble-shooting) .
  2. Adjust auxiliary air delivery with auxiliary controls on rear of center console. Air discharge from outlets should correspond with selections on auxiliary controls. If air delivery is not correct, see appropriate procedure in «TROUBLE SHOOTING»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville__trouble-shooting) .
  3. Outside (ambient) air temperature on display should match actual outside air temperature. If not, see appropriate procedure in «TROUBLE SHOOTING»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville__trouble-shooting) .

Note. DTCs can be recorded at various operating times. Some codes require operation of that sensor or switch for 5 seconds; others require operation for 5 minutes or longer at normal operating temperature, vehicle speed, and load. Therefore, some DTCs may not be duplicated in a service bay and may require road testing vehicle in order to duplicate conditions under which DTC will set.

BLOWER HAS HIGH SPEED ONLY

  1. Turn ignition switch to ON position. Set blower motor seed to LOW. Disconnect blower motor connector. Using DVOM, measure voltage between blower control module connector terminal "A" (Black wire) and terminal "C" (Gray/Black wire). If reading is 6 volts, go to next step. If reading is not 6 volts, go to step 4 .
  2. Reconnect blower motor connector. If blower motor operates at high speed, go to next step. If blower motor does not operate at high speed, system is operating properly.
  3. Replace blower motor. See «BLOWER MOTOR»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) under REMOVAL & INSTALLATION. Recheck operation of blower motor.
  4. Using DVOM, measure voltage between ground and blower control module connector terminal "C" (Gray/Black wire). If voltage is 4.0-5.0 volts, go to next step. If voltage is not 4.0-5.0 volts, go to step 6 .
  5. Replace blower control module. See «BLOWER CONTROL MODULE»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) under REMOVAL & INSTALLATION. Recheck operation of blower motor.
  6. Replace instrument panel integration module. Recheck operation of blower motor.

BLOWER MOTOR INOPERATIVE IN ALL SPEEDS

  1. Disconnect blower control module. Turn ignition switch to ON position. Using DVOM, measure voltage between ground and blower control module connector terminal "B" (Orange wire). If reading is more than 5.0 volts, go to next step. If reading is less than 5.0 volts, go to step 7 .
  2. Using DVOM, measure resistance of Black wire between ground and blower control module connector terminal "A". If reading is zero ohms (continuity), go to next step. If reading is not zero ohms, go to step 8 .
  3. Set blower motor to LO setting. Using DVOM, measure voltage between ground and blower control module connector terminal "C" (Gray/Black wire). If reading is less than 9 volts, go to step 8 . If reading is more than 9 volts, go to next step.
  4. Set blower motor to HI setting. Using DVOM, measure voltage between ground and blower control module connector terminal "C" (Gray/Black wire). If reading is less than 3 volts, go to step 6 . If reading is more than 3 volts, go to next step.
  5. Check Gray/Black wire between blower control module connector and instrument panel integration module connector terminal C1 for short to ground. If repair was made, go to step 12 . If wire is okay, go to step 9 .
  6. Using DVOM, measure voltage between blower motor connector terminals "A" (Purple wire) and "B" (Black wire). If reading is more than 5.0 volts, go to step 10 . If reading is less than 5.0 volts, go to step 11 .
  7. Check Orange wire between blower control module connector and HVAC BLO (30-amp) fuse for open or short to ground. If repair was made, go to step 12 .
  8. Repair open or short to voltage in Black wire between blower control module connector and ground. Go to step 12 .
  9. Replace instrument panel integration module. Go to step 12 .
  10. Replace blower motor. Go to step 12 .
  11. Replace blower control module. Go to next step.
  12. Recheck operation of blower motor.

AUXILIARY BLOWER MOTOR INOPERATIVE AT ANY SPEED

  1. Install scan tool. Turn ignition on. Set rear blower motor control to highest setting. If scan tool indicates Rear Integration Module (RIM) requesting rear blower operation, go to next step. If no request is made, go to step 5 .
  2. Using DVOM, measure voltage between ground and blower motor connector terminal "A" (Yellow wire). If reading is more than 5.0 volts, go to step 6 . If reading is less than 5.0 volts, go to next step.
  3. Using DVOM, measure voltage between ground and RR BLO relay connector terminal No. 85 (Tan wire). If reading is zero volts, go to step 11 . If reading is not zero volts, go to next step.
  4. Check Tan wire between ground and RR BLO relay connector terminal No. 85 and RIM connector terminal A6 for an open condition. If repair was made, go to step 12 . If wire is okay, go to step 9 .
  5. Using DVOM, measure voltage between ground and rear blower switch connector terminal "J" (Orange wire). If reading is more than 5.0 volts, go to step 7 . If reading is less than 5.0 volts, go to next step.
  6. Check Orange wire between rear blower motor switch connector terminal "J" and rear blower motor connector for open or short to ground. If repair was made, go to step 12 . If wire is okay, go to step 8 .
  7. Using DVOM, measure voltage between ground and rear blower motor switch connector terminal "A" (Black wire). If reading is more than 5.0 volts, go to step 9 . If reading is less than 5.0 volts, go to step 10 .
  8. Check Black wire between blower motor switch connector terminal "A" and ground for an open condition. If repair was made, go to step 12 .
  9. Replace rear integration module. Go to step 12 .
  10. Replace rear blower switch. Go to step 12 .
  11. Replace RR BLO relay. Go to next step.
  12. Recheck operation of auxiliary blower motor.

COMPRESSOR CLUTCH DOES NOT ENGAGE

  1. Connect scan tool. Start engine. If any Diagnostic Trouble Codes (DTCs) set by Dash Integration Module (DIM) are present, go to appropriate DTC procedure under «SELF-DIAGNOSTICS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . If no DTCs are present, go to next step.
  2. Use scan tool to view DIM data. If compressor clutch is ON, go to step 9 . If compressor clutch is not ON, go to next step.
  3. View A/C pressure status with scan tool. If status is okay, go to next step. If not okay, go to step 6 .
  4. Check battery voltage display on scan tool. If reading is more than 5.0 volts, go to next step. If reading is less than 5.0 volts, see appropriate GENERATORS & REGULATORS article in STARTING & CHARGING SYSTEMS.
  5. Check A/C temperature status with scan tool. If status is okay, go to next step. If status is not okay, see REFRIGERANT SYSTEM DIAGNOSIS in MANUAL A/C-HEATER SYSTEMS - TROUBLE SHOOTING article.
  6. Check HVAC system pressure with scan tool. If system pressure is okay, go to next step. If system pressure is low, see REFRIGERANT SYSTEM DIAGNOSIS in MANUAL A/C-HEATER SYSTEMS - TROUBLE SHOOTING article.
  7. Check A/C CLU (15-amp) fuse. If fuse is open, go to next step. If fuse is okay, go to step 10 .
  8. Replace A/C CLU (15-amp) fuse and go to step 19 .
  9. Depress A/C button on HVAC control panel. Using DVOM, measure voltage between compressor clutch connector terminals "A" (Dark Green wire) and "B" (Black wire). If reading is more than 5.0 volts, go to step 15 . If reading is less than 5.0 volts, go to step 7 .
  10. Using DVOM, measure voltage between ground and compressor clutch connector Dark Green wire terminal. If reading is more than 5.0 volts, go to step 16 . If reading is less than 5.0 volts, go to next step.
  11. Remove A/C CLU relay. Using DVOM, measure voltage between ground and A/C CLU relay connector terminal No. 30 in underhood junction block. If reading is more than 5.0 volts, go to step 17 . If reading is less than 5.0 volts, go to next step.
  12. Using DVOM, measure voltage between ground and A/C CLU relay connector terminal No. 86 in underhood junction block. If reading is more than 5.0 volts, go to step 13 . If reading is less than 5.0 volts, go to step 19 .
  13. Using DVOM, measure voltage between ground and Powertrain Control Module (PCM) connector terminal No. 27 (Dark Green/White wire). If reading is more than 5.0 volts, go to step 18 . If reading is less than 5.0 volts, go to next step.
  14. Repair Dark Green/White wire between A/C CLU relay connector terminal No. 85 and PCM connector terminal No. 27 for open or short to ground. Go to step 20 .
  15. Replace A/C compressor. Go to step 20 .
  16. Repair open in Black wire between compressor clutch connector and ground. Go to step 20 .
  17. Replace A/C CLU relay. Go to step 20 .
  18. Replace PCM. Go to step 20 .
  19. Repair connection at A/C CLU relay connector terminal No. 86, or open condition between relay and A/C CLU (15-amp) fuse. Go to next step.
  20. Recheck compressor operation.

COMPRESSOR CLUTCH DOES NOT DISENGAGE

  1. Connect scan tool. Start engine. Turn A/C off. If scan tool indicates compressor clutch requested ON by Powertrain Control Module (PCM), go to step 4 . If request by PCM is not indicated, go to next step.
  2. If compressor clutch is requested on by Instrument Panel Integration Module (IPM), go to step 10 . If not, go to next step.
  3. If compressor clutch is requested on by Dash Integration Module (DIM), go to step 11 . If not, go to next step.
  4. Replace PCM. Recheck compressor clutch operation.
  5. Disconnect A/C CLU relay. If compressor clutch disengages, go to step 7 . If compressor clutch does not disengage, go to next step.
  6. Repair short to battery voltage in Purple wire between Data Link Connector (DLC) and PCM connector terminal No. 59. Recheck compressor clutch operation.
  7. Using DVOM, measure resistance between ground and A/C CLU relay connector terminal No. 85 (Dark Green/White wire). If zero ohms (continuity) is indicated, go to next step. If reading is not zero ohms, go to step 9 .
  8. Replace A/C CLU relay. Recheck compressor clutch operation.
  9. Repair short to ground in Dark Green/White wire between PCM connector terminal No. 27 and A/C CLU relay connector terminal No. 85. Recheck compressor clutch operation.
  10. Replace IPM. Recheck compressor clutch operation.
  11. Replace DIM. Recheck compressor clutch operation.

IMPROPER AIR DELIVERY

  1. Connect scan tool. Start engine. Use scan tool to view HVAC Diagnostic Trouble Codes (DTCs). If any HVAC DTCs are present, go to appropriate DTC under «SELF-DIAGNOSTICS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . If no DTCs are present, go to next step.
  2. Use scan tool to view actuator data. Adjust airflow with MODE button. If airflow changes discharge locations, go to step 4 . If airflow does not change, go to next step.
  3. Use scan tool to adjust mode operation. If airflow changes discharge locations, go to step 6 . If airflow does not change, go to next step.
  4. Check actuator and mode valves for binding or mechanical failure. If binding or failure was found and repaired, go to step 7 . If actuators and mode valves are okay, go to next step.
  5. Replace mode actuator. Go to step 7 .
  6. Replace instrument panel integration module. Go to next step.
  7. Check that air delivery system is operating properly.

AUXILIARY AIR DELIVERY INOPERATIVE

  1. Turn ignition switch to ON position. Using DVOM, measure voltage between ground and rear mode actuator connector terminal No. 10 (Brown wire). If reading is more than 5.0 volts, go to next step. If reading is less than 5.0 volts, go to step 6 .
  2. Using DVOM, measure voltage between ground and rear blower switch connector terminal No. 8 (Pink wire). If reading is more than 5.0 volts, go to next step. If reading is less than 5.0 volts, go to step 6 .
  3. Turn rear blower switch to OFF position. Using DVOM, measure voltage between ground and rear mode actuator connector terminal No. 8 (Pink wire). If reading is more than 5.0 volts, go to next step. If reading is less than 5.0 volts, go to step 7 .
  4. Using DVOM, measure resistance between ground and rear mode actuator connector terminal No. 8 (Pink wire). If reading is zero ohms resistance (continuity), go to next step. If reading is not zero ohms, go to step 7 .
  5. Replace rear mode actuator. Go to step 10 .
  6. Check for open or short in Brown wire between rear blower switch, HVAC (10-amp) fuse and rear mode actuator. Go to step 10 .
  7. Using DVOM, measure voltage between ground and rear blower switch connector terminal "K" (Pink wire). If reading is more than 5.0 volts, go to next step. If reading is less than 5.0 volts, go to step 9 .
  8. Repair Pink wire between rear mode actuator connector terminal No. 8 and rear blower switch connector terminal "K" for open or short. Go to step 10 .
  9. Replace rear blower switch. Go to next step.
  10. Recheck operation of rear mode control and blower motor.

AIR TEMPERATURE CONTROL INOPERATIVE

  1. Perform diagnostic system check. See «DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville__hvac-diagnostic-system-check) . Go to next step.
  2. Connect scan tool. Check for HVAC DTCs. If any HVAC DTCs are present, go to appropriate DTC under «SELF-DIAGNOSTICS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . If no HVAC DTCs are present, go to next step.
  3. Use scan tool to view HVAC system pressures. If pressures are within specifications, go to next step. If pressures are not within specification, see REFRIGERANT SYSTEM DIAGNOSIS in MANUAL A/C-HEATER SYSTEMS - TROUBLE SHOOTING article.
  4. Start engine and bring to operating temperature. Ambient temperature should be more than 48°F (8°C). Set temperature control to 85°F (29°C). Set passenger control to coldest setting. Check temperature at passenger and driver side center outlets. If right center outlet is cooler than left center outlet, go to next step. If no temperature difference exists, go to step 6 .
  5. Set temperature control to 65°F (18°C). Set passenger control to warmest setting. Check temperature at passenger and driver side center outlets. If right center outlet is cooler than left center outlet, system is operating properly. If no temperature difference exists, go to next step.
  6. Check temperature door/actuator for proper mounting and movement. If door/actuator are operating properly, go to step 8 . If repair is needed, go to next step.
  7. Repair door/actuator. Go to step 9 .
  8. Discharge HVAC system, using approved refrigerant recovery/recycling equipment. Evacuate, charge, and leak test HVAC system. Go to next step.
  9. Recheck operation of temperature control function.

AIR TEMPERATURE DISPLAY INACCURATE

  1. If engine is at operating temperature, allow engine to cool for 2 hours or more. Engine MUST be cool. Install scan tool. Check outside (ambient) temperature with scan tool. If scan tool and HVAC control panel indicate same temperature, go to step 1 . If displayed temperatures are different, go to next step.
  2. Remove ambient air temperature sensor. See «SENSORS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) under REMOVAL & INSTALLATION. Using DVOM, measure resistance across ambient air temperature pins. Check reading with ambient sensor resistance table. See «OUTSIDE (AMBIENT) TEMPERATURE SENSOR RESISTANCE»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) table under TESTING. If reading is within specifications, go to step 4 . If reading is not within specifications, go to next step.
  3. Replace ambient air temperature sensor. Go to step 5 .
  4. Check Instrument Panel Integration Module (IPM) connector for proper contact. If connections are okay, replace IPM. Go to next step.
  5. Recheck operation of ambient air temperature sensor.

RETRIEVING DIAGNOSTIC TROUBLE CODES

Connect scan tool to DLC connector located under instrument panel. Select IPM or HVAC. Select DTC. Select CURRENT DTC for current DTCs or HISTORY DTC for history DTCs.

DTCCircuit Affected
B1310Outside (Ambient) Air Temperature Sensor
B1317Inside Air Temperature Sensor
B1318/B1328Left Sun Load Sensor/Right Sun Load Sensor
B1321A/C Refrigerant Low-Side Temperature Sensor
B1324A/C Refrigerant Pressure
B1330Left A/C Temperature Sensor
B1331Right A/C Temperature Sensor
B1332Left Heater Temperature Sensor
B1333Right Heater Temperature Sensor
B1340Left Air Mix Actuator
B1341Right Air Mix Actuator
B1343Air Inlet Actuator
B1344HTR/DEF/AC Air Inlet Actuator
B1399Loss Of KDD Communications
B2510Steering Wheel Switches

HVAC DIAGNOSTIC TROUBLE CODE DEFINITIONS

Note. For complete information on all PCM and IPC Diagnostic Trouble Codes (DTC), see appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE or appropriate INSTRUMENT PANELS article in ACCESSORIES & EQUIPMENT.

CLEARING DIAGNOSTIC TROUBLE CODES

Enter self diagnostics. Select IPM or HVAC. Select DTC. Select CLEAR CODES. Press YES button to clear codes.

Circuit Description

On 2000 models, ambient air temperature sensor is a thermistor that controls signal voltage to IPM. IPM supplies voltage on circuit No. 735 (Light Green/Black wire). When sensor is cold, sensor resistance is high. IPM senses high signal voltage at connector C2 terminal B1 (Light Green/Black wire). When sensor warms, resistance is low and signal voltage is low through circuit No. 61 (Yellow wire).

On 2001 models, HVAC control module (IPM) monitors outside air temperature using ambient air temperature sensor. When air temperature is cold, sensor resistance and signal voltage are high. When air temperature is warm, sensor resistance and signal voltage are low.

Conditions For Setting DTC

On 2000 models, DTC will set when ignition is turned on and IPM detects a signal circuit open or short. Signal voltage will vary from 5.0 volts (open circuit) to zero volts (short circuit). IPM will use a default value of 59°F (15°C) to allow operation of HVAC system and a blank will be displayed on driver's information center. DTC can be cleared using a scan tool or interrupting IPM battery voltage. A current DTC will clear when system diagnostic runs and does not fail.

On 2001 models, DTC will set when ignition is on and IPM detects a signal that is less than 0.09 volts (5 counts) or more than 4.90 volts (250 counts). When DTC sets, IPM uses a default value for sensor data. Scan tool displays default OUTSIDE AIR TEMP VALUE in IPM HVAC SENSORS data list. IPM will display "- -" for ambient air temperature when ignition is off. IPM will display set temperature when on. DTC will become history if IPM no longer detects a failure. History DTC will clear after 50 fault free ignition cycles. DTC can be cleared using a scan tool.

DTC Testing (2000 Models)

  1. Perform diagnostic system check. If diagnostic system check has not been performed, see «DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville__hvac-diagnostic-system-check) . If diagnostic system check has been performed, go to next step.
  2. Disconnect ambient air temperature sensor 2-pin connector. Turn ignition on. Measure voltage between sensor connector terminals "A" (Light Green/Black wire) and "B" (Yellow wire). See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . If voltage is 5.0 volts, go to next step. If voltage is not 5.0 volts, go to step 4 .
  3. Turn ignition off. Reconnect sensor 2-pin connector. Turn ignition on. Using scan tool, clear DTC. Start engine and allow to idle. If DTC resets, go to next step. If DTC does not reset, check wiring harness between ambient air temperature sensor and IPM. Repair as necessary.
  4. Connect a scan tool. Select IPM open/short data. Display ambient air temperature data. Start engine and allow to idle. Disconnect ambient air temperature sensor connector. Ambient temperature sensor voltage should increase to 5.0 volts. Reconnect ambient temperature sensor connector. If sensor voltage decreases, go to next step. If sensor voltage does not decrease, go to step 6 .
  5. Replace ambient air temperature sensor and go to step 7 . See «SENSORS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) under REMOVAL & INSTALLATION.
  6. Check circuit No. 61 (Yellow wire) for an open or a short between ambient air temperature sensor and ground connection. See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . If an open or a short is not found, go to next step. If an open or a short is found, go to step 8 .
  7. Check circuit No. 735 (Light Green/Black wire) for an open or a short between ambient air temperature sensor and IPM. Repair as necessary. If circuit is okay, replace IPM. See «HVAC CONTROL PANEL»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) under REMOVAL & INSTALLATION. When repairs are complete, go to step 9 .
  8. Repair open or short in circuit No. 61 (Yellow wire). See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . When repairs are complete, go to next step.
  9. Using scan tool, clear all DTCs. Ensure HVAC system is operating properly. See «DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville__hvac-diagnostic-system-check) .

DTC Testing (2001 Models)

  1. Perform diagnostic system check. If diagnostic system check has not been performed, see «DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville__hvac-diagnostic-system-check). If diagnostic system check has been performed, go to next step.
  2. Install a scan tool. Turn ignition on, with engine off. Using scan tool, observe OUTSIDE AIR TEMP parameter in IPM Open/Short data list. If scan tool indicates OUTSIDE AIR TEMP parameter is not 5-250 counts (0.09-4.90 volts), go to next step. If indicated parameter is 5-250 counts (0.09-4.90 volts), check circuits No. 61 (Yellow wire) and No. 735 (Light Green/Black wire) for intermittent or poor connections. See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville). Repair as necessary.
  3. Turn ignition off. Disconnect ambient air temperature sensor. Turn ignition on, with engine off. Using scan tool, observe OUTSIDE AIR TEMP parameter in IPM Open/Short Data list. If scan tool indicates OUTSIDE AIR TEMP parameter is more than 250 counts (4.90 volts), go to next step. If indicated parameter is less than 250 counts (4.90 volts), go to step 5.
  4. Turn ignition off. Connect a 3-amp fused jumper wire between ambient air temperature sensor connector terminals. Turn ignition on, with engine off. Using scan tool, observe OUTSIDE AIR TEMP parameter in IPM Open/Short Data list. If scan tool indicates OUTSIDE AIR TEMP parameter is less than 5 counts (0.09 volts), go to step 8. If indicated parameter is more than 5 counts (0.09 volts), go to step 6.
  5. Check for a short to ground in Light Green/Black wire between ambient air temperature sensor and IPM 24-pin connector C1 terminal B1. (Scheme 5) See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville). Repair as necessary. If wire is okay, go to step 9. When repairs are completed, go to step 12.
  6. Check for a short to voltage, high resistance, or an open in Light Green/Black wire between ambient air temperature sensor and IPM 24-pin connector C1 terminal B1. (Scheme 5) See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville). Repair as necessary. If wire is okay, go to next step. When repairs are completed, go to step 12.
  7. Check for high resistance or an open in Yellow wire between ambient air temperature sensor and IPM 24-pin connector C1 terminal B8. (Scheme 5) See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville). Repair as necessary. If wire is okay, go to step 9. When repairs are completed, go to step 12.
  8. Check wiring harness for poor connection and loose or damaged terminals at ambient air temperature sensor. See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville). Repair as necessary. If wiring harness is okay, go to step 10. When repairs are completed, go to step 12.
  9. Check wiring harness for poor connections and loose or damaged terminal at IPM. (Scheme 5) See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville). Repair as necessary. If wiring harness is okay, go to step 11. When repairs are completed, go to step 12.
  10. Replace ambient air temperature sensor. See «SENSORS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) under REMOVAL & INSTALLATION. When repairs are completed, go to step 12.
  11. Replace IPM. See «HVAC CONTROL PANEL»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) under REMOVAL & INSTALLATION. When repairs are completed, go to next step.
  12. Using scan tool, clear any DTCs. Operate vehicle within conditions that set DTC. See «CONDITIONS FOR SETTING DTC»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville__conditions-for-setting-dtc). If DTC resets, go to step 2. If DTC does not reset, system is operating properly.

Scheme 5

Scheme 5
Scheme 5

On 2000 models, inside air temperature sensor is a thermistor that controls signal voltage to Instrument Panel Integration Module (IPM). Inside air temperature sensor contains an electric fan which pulls air from passenger compartment to sensor. IPM applies voltage on circuit No. 734. When sensor is cold, resistance is high and circuit No. 734 signal voltage at IPM connector C2 terminal B4 (Dark Green wire) will be high. When sensor is warm, resistance is low and circuit No. 61 signal voltage at IPM connector C2 terminal B8 (Yellow wire) will be low. Signal voltage will vary from 5.0 volts (open circuit) to zero volts (short circuit).

On 2001 models, HVAC control module (IPM) monitors inside air temperature through an inside air temperature assembly. Inside air temperature assembly contains an electric fan which pulls air from passenger compartment to sensor. When air is cold, sensor resistance and signal voltage are high. When air is warm, sensor resistance and signal voltage are low. IPM requests A/C compressor clutch engagement and controls air temperature actuator door positions in order to maintain selected air temperature on IPM.

On 2000 models, DTC will set when ignition is on, DTC B1310 is not set and IPM detects a circuit open or short. When DTC is set, IPM will use a default value of 75°F (24°C) to allow operation of HVAC system. DTC can be cleared using a scan tool. DTC can be cleared using a scan tool or interrupting IPM battery voltage. A current DTC will clear when system diagnostic runs and does not fail.

On 2001 models, DTC will set when ignition is on and IPM detects an inside air temperature signal circuit less than 5 counts (0.09 volts) or more than 250 counts (4.90 volts). IPM will use a default value for sensor data. Scan tool displays a default INSIDE AIR TEMP value in IPM HVAC Sensors data list. Scan tool displays actual INSIDE AIR TEMP value in IPM Open/Short data list. DTC will become history if IPM no longer detects a failure. History DTC will clear after 50 fault free ignition cycles. DTC can be cleared using a scan tool.

  1. Perform diagnostic system check. If diagnostic system check has not been performed, see «DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville__hvac-diagnostic-system-check). If diagnostic system check has been performed, go to next step.
  2. Disconnect inside air temperature sensor 4-pin connector. Turn ignition on. Measure voltage between sensor harness connector terminals "A" (Dark Green wire) and "D" (Yellow wire). If voltage is 5.0 volts, go to next step. If voltage is not 5.0 volts, go to step 7.
  3. Turn ignition off. Reconnect sensor connector. Turn ignition on. Using scan tool, clear DTC. Start engine and allow to idle. If DTC resets, go to next step. If DTC does not reset, check wiring harness between inside air temperature sensor and IPM. Repair as necessary.
  4. Connect a scan tool and display inside air temperature data. Start engine and allow to idle. Disconnect inside air temperature sensor. When inside air temperature sensor voltage increases, reconnect inside air temperature sensor connector. If sensor voltage does not decrease, go to next step. If sensor voltage decreases, go to step 6.
  5. Check for an open or a short in circuit No. 734 (Dark Green wire) between inside air temperature sensor and IPM 24-pin connector C2 terminal B4. (Scheme 5) See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville). Repair as necessary. If circuit is okay, replace IPM. See «HVAC CONTROL PANEL»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) under REMOVAL & INSTALLATION. When repairs are completed, go to step 13.
  6. Replace inside air temperature sensor. See «SENSORS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) under REMOVAL & INSTALLATION. When repairs are completed, go to step 13.
  7. Measure voltage between ground and inside air temperature sensor connector terminal "A" (Dark Green wire). If voltage is 5.0 volts, go to next step. If voltage is not 5.0 volts, go to step 10.
  8. Using scan tool, check for HVAC sensor DTCs. If all HVAC sensor DTCs present are present, go to next step. If no HVAC sensor DTCs are present, go to step 12.
  9. Check circuit No. 61 (Yellow wire) for an open or a short condition between all sensors and IPM connector C2 terminal B8. (Scheme 5) See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville). Repair as necessary. When repairs are completed, go to step 13.
  10. Measure voltage between ground and IPM 24-pin connector C2 terminal B4 (Dark Green wire). If voltage is 5.0 volts, go to next step. If voltage is not 5.0 volts, go to step 5.
  11. Repair open in circuit No. 734 (Dark Green wire) between sensor and IPM. See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville). When repairs are completed, go to step 13.
  12. Repair open in circuit No. 61 (Yellow wire) between sensor and IPM. See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville). When repairs are completed, go to next step.
  13. Using scan tool, clear any DTCs. Operate vehicle within conditions that set DTC. See «CONDITIONS FOR SETTING DTC»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville). If DTC resets, go to step 2. If DTC does not reset, system is operating properly.
  1. Perform diagnostic system check. If diagnostic system check has not been performed, see «DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville__hvac-diagnostic-system-check). If diagnostic system check has been performed, go to next step.
  2. Install a scan tool. Turn ignition on, with engine off. Using scan tool, observe INSIDE AIR TEMP parameter in IPM Open/Short Data list. If indicated INSIDE AIR TEMP parameter is 5-250 counts (0.09-4.90 volts), check wiring harness between inside air temperature sensor and IPM. Repair as necessary. If parameter is not 5-250 counts (0.09-4.90 volts), go to next step.
  3. Turn ignition off. Disconnect inside air temperature assembly. Turn ignition on, with engine off. Using scan tool, observe INSIDE AIR TEMP parameter in IPM Open/Short Data list. If indicated INSIDE AIR TEMP parameter is more than 250 counts (4.90 volts), go to next step. If indicated parameter is less than 250 counts (4.90 volts), go to step 5.
  4. Turn ignition off. Connect a 3-amp fused jumper wire between inside air temperature connector terminals "A" (Dark Green wire) and "D" (Yellow wire). Turn ignition on, with engine off. Using scan tool, observe INSIDE AIR TEMP parameter in IPM Open/Short Data list. If indicated parameter is less than 5 counts (0.09 volts), go to step 8. If indicated parameter is more than 5 counts (0.09 volts), go to step 6.
  5. Check for a short to ground in Dark Green wire between inside air temperature connector terminals "A" and IPM 24-pin connector terminal B1. (Scheme 5) See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville). Repair as necessary. When repairs are completed, go to step 12. If wire is okay, go to step 9.
  6. Check for a short to voltage, a high resistance, or an open in Dark Green wire between inside air temperature connector terminals "A" and IPM 24-pin connector terminal B1. (Scheme 5) See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville). Repair as necessary. When repairs are completed, go to step 12. If wire is okay, go to next step.
  7. Check for high resistance or an open in Yellow wire between inside air temperature connector terminals "D" and IPM 24-pin connector terminal B8. (Scheme 5) See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville). Repair as necessary. When repairs are completed, go to step 12. If wire is okay, go to step 9.
  8. Check wiring harness for poor connection and loose or damaged terminals at inside air temperature sensor. See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville). Repair as necessary. When repairs are completed, go to step 12. If wiring harness is okay, go to step 10.
  9. Check wiring harness for poor connections and loose or damaged terminal at IPM. (Scheme 5) See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville). Repair as necessary. When repairs are completed, go to step 12. If wiring harness is okay, go to step 11.
  10. Replace inside air temperature sensor. See «SENSORS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) under REMOVAL & INSTALLATION. When repairs are completed, go to step 12.
  11. Replace IPM. See «HVAC CONTROL PANEL»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) under REMOVAL & INSTALLATION. When repairs are completed, go to next step.
  12. Using scan tool, clear any DTCs. Operate vehicle within conditions that set DTC. See «CONDITIONS FOR SETTING DTC»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville). If DTC resets, go to step 2. If DTC does not reset, system is operating properly.

On 2000 models, sun load sensors are light sensitive photodiodes that control signal voltage to Instrument Panel Integration Module (IPM). Because photodiodes are different from standard thermistor sensors, resistance measurements will not produce accurate results. IPM monitors voltage on circuit No. 590 (left sun load sensor) and circuit No. 1548 (right sun load sensor). When sensor is in direct sun light, IPM reads a low signal voltage. When sensor is shaded, signal voltage increases. Signal voltage will vary from 5.0 volts (open circuit) to zero volts (short circuit).

On 2001 models, HVAC control module (IPM) monitors ambient light on left and right side of vehicle through a light sensitive photodiode called left sunload sensor or right side sunload sensor. IPM uses this information to compensate for effects of sun on inside air temperature of vehicle. When sensor is in direct sunlight, signal voltage is low. When sensor is shaded, signal voltage is high. IPM requests A/C compressor clutch engagement and controls right air temperature actuator door positions in order to maintain selected air temperature on IPM.

On 2000 models, DTC will set when ignition is on and IPM has detected a circuit open or short. When DTC sets, IPM will default to dark or no sun load value so HVAC system will operate. DTC will clear when system diagnostic runs and does not fail or IPM battery voltage is interrupted.

On 2001 models, DTC will set when ignition is on and IPM detects signal circuit is less than 5 counts (0.09 volts) or more than 250 counts (4.90 volts). When DTC sets, IPM uses a default value so HVAC system will operate. Scan tool displays default LEFT SOLAR or RIGHT SOLAR value in IPM HVAC Sensors data list. Scan tool displays actual LEFT SOLAR SENSOR or RIGHT SOLAR SENSOR value in IPM Open/Short data list. DTC will become history if IPM no longer detects a failure. History DTC will clear after 50 fault free ignition cycles. DTC can be cleared using a scan tool.

  1. Perform diagnostic system check. If diagnostic system check has not been performed, see «DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville__hvac-diagnostic-system-check). If diagnostic system check has been performed, go to next step.
  2. Position vehicle outside in a sunlit area. Turn ignition on. Connect a scan tool. Display suspect sun load sensor and record sensor count. Cover suspect sun load sensor with a shop rag. If sensor count increases from recorded count, go to next step. If sensor count does not increase, go to step 4.
  3. Using scan tool, clear DTC. Start engine and allow to idle. If DTC resets, go to next step. If DTC does not reset, check wiring harness for poor connection and loose or damaged terminals at suspect sun load sensor. See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville). Repair as necessary.
  4. Turn ignition off. Disconnect suspect sun load sensor. Turn ignition on. Measure voltage between suspect sun load sensor connector terminals "A" (Light Blue/Black wire on left side; Gray wire on right side) and "B" (Yellow wire). If voltage is 5.0 volts, go to step 8. If voltage is not 5.0 volts, go to next step.
  5. Measure voltage between ground and suspect sun load sensor connector terminal "A" (Light Blue/Black wire on left side; Gray wire on right side). If voltage is 5.0 volts, go to step 9. If voltage is not 5.0 volts, go to next step.
  6. Measure voltage between ground and IPM 24-pin connector terminal B2 (Light Blue/Black wire) for left sensor or terminal B3 (Gray wire) for right sensor. If voltage is 5.0 volts, go to next step. If voltage is not 5.0 volts, go to step 10.
  7. Repair an open or short in circuit No. 590 (Light Blue/Black wire) for left sensor or circuit No. 1548 (Gray wire) for right sensor between IPM and sun load sensor. Repair as necessary. When repairs are completed, go to step 12.
  8. Replace suspect sun load sensor. See «SENSORS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) under REMOVAL & INSTALLATION. When repairs are completed, go to step 12.
  9. Using scan tool, check for HVAC sensor DTCs. If all HVAC sensor DTCs are present, go to next step. If HVAC sensor DTCs are not present, go to step 11.
  10. Check IPM connectors for loose or damaged terminals. (Scheme 5) See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville). Repair as necessary. If connectors and terminals are okay, replace IPM. See «HVAC CONTROL PANEL»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) under REMOVAL & INSTALLATION. When repairs are completed, go to step 12.
  11. Repair an open or short in circuit No. 61 (Yellow wire) between IMP 24-pin connector C2 terminal B8 and suspect sun load sensor. When repairs are completed, go to next step.
  12. Using scan tool, clear any DTCs. Operate vehicle within conditions that set DTC. See «CONDITIONS FOR SETTING DTC»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville). If DTC resets, go to step 2. If DTC does not reset, system is operating properly.
  1. Perform diagnostic system check. If diagnostic system check has not been performed, see «DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville__hvac-diagnostic-system-check). If diagnostic system check has been performed, go to next step.
  2. Install a scan tool. Turn ignition on, with engine off. Using scan tool, observe suspect SOLAR SENSOR parameter in IPM, Open/Short Data list. If scan tool indicates solar sensor parameter is 5-250 counts, check wiring harness for poor connection and loose or damaged terminals at suspect sun load sensor. See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville). Repair as necessary. If indicated parameter is not 5-250 counts, go to next step.
  3. Turn ignition off. Disconnect suspect sunload sensor. Turn ignition on, with engine off. Using scan tool, observe suspect SOLAR SENSOR parameter in IPM, Open/Short Data list. If scan tool indicates that suspect SOLAR SENSOR parameter is more than 250 counts, go to next step. If indicated parameter is not more than 250 counts, go to step 5.
  4. Turn ignition off. Connect a 3-amp fused jumper wire between suspect sunload sensor connector terminals. See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville). Turn ignition on, with engine off. Using scan tool, observe suspect SOLAR SENSOR parameter in IPM, Open/Short Data list. If scan tool indicates SOLAR SENSOR parameter is less than 5 counts, go to step 8. If indicated parameter is not less than 5 counts, go to step 6.
  5. Check for a short to ground in signal circuit (Light Blue/Black wire on left side or Gray wire on right side) between suspect sunload sensor and IPM. (Scheme 5) See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville). Repair as necessary. If signal circuit is okay, go to step 9. When repairs are completed, go to step 12.
  6. Check for a short to voltage, high resistance, or an open in signal circuit (Light Blue/Black wire on left side or Gray wire on right side) between suspect sunload sensor and IPM. (Scheme 5) See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville). Repair as necessary. If signal circuit is okay, go to next step. When repairs are completed, go to step 12.
  7. Check for high resistance or an open in low reference circuit (Yellow wire) between suspect sunload sensor and IPM. (Scheme 5) See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville). Repair as necessary. If signal circuit is okay, go to step 9. When repairs are completed, go to step 12.
  8. Check suspect sun load sensor connector for loose or damaged terminals. See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville). Repair as necessary. If connectors and terminals are okay, go to step 10. When repairs are completed, go to step 12.
  9. Check IPM connectors for loose or damaged terminals. (Scheme 5) See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville). Repair as necessary. If connectors and terminals are okay, go to step 11. When repairs are completed, go to step 12.
  10. Replace suspect sunload sensor. See «SENSORS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) under REMOVAL & INSTALLATION. When repairs are completed, go to step 12.
  11. Replace IPM. See «HVAC CONTROL PANEL»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) under REMOVAL & INSTALLATION. When repairs are completed, go to next step.
  12. Using scan tool, clear any DTCs. Operate vehicle within conditions that set DTC. See «CONDITIONS FOR SETTING DTC»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville). If DTC resets, go to step 2. If DTC does not reset, system is operating properly.

On 2000 models, A/C low side temperature sensor is a thermistor that controls signal voltage to Dash Integration Module (DIM). DIM supplies voltage on circuit No. 731. When sensor is cold, resistance is high and DIM will sense a high signal voltage at DIM connector C2 terminal A7 (Gray wire). When sensor is warm, resistance is low and signal voltage is low through circuit 470 (Black wire). Signal voltage will vary from 5.0 volts (open circuit) to zero volts (short circuit).

On 2001 models, Dash Integration Module (DIM) monitors refrigerant temperature through an A/C refrigerant low temperature sensor. When refrigerant is cold, sensor resistance and signal voltage are high. When refrigerant is warm, sensor resistance and signal voltage are low. DIM will not request A/C compressor clutch engagement when A/C refrigerant low temperature sensor is out of range. DTC will set when ignition is turned on and DIM detects a signal circuit less than 0.09 volt or more than 4.90 volts.

On 2000 models, DTC will set when ignition is on and a circuit short or open is detected. When DTC sets, A/C compressor clutch will not engage, driver information center will display service HVAC system and a default temperature reading of 43°F (6°C) will be implemented. DTC is cleared using a scan tool, when diagnostic runs and does not fail or battery voltage to DIM is interrupted.

On 2001 models, when DTC sets, DIM will use a default value to allow operation of HVAC system. Driver information center will display SERVICE A/C SYSTEM. DTC will become history if DIM no longer detects a failure. History DTC will clear after 40 fault free ignition cycles. DTC can be cleared using a scan tool.

  1. If diagnostic system check has not been performed, see «DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville__hvac-diagnostic-system-check) . If diagnostic system check has been performed, go to next step.
  2. Turn ignition off. Disconnect A/C low side temperature sensor 2-pin connector. Turn ignition on. Measure voltage between A/C low side temperature sensor connector terminals. See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . If voltage is about 5.0 volts, go to step 4 . If voltage is not about 5.0 volts, go to next step.
  3. Backprobe Dash Integration Module (DIM) 24-pin Light Blue connector C2 and measure voltage between terminals A6 (Black wire) and A7 (Gray wire). If voltage is about 5.0 volts, go to step 6 . If voltage is not about 5.0 volts, go to step 5 .
  4. Replace A/C low side temperature sensor. See «SENSORS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) under REMOVAL & INSTALLATION. When repairs are completed, go to step 8 .
  5. Replace DIM. See «DASH INTEGRATION MODULE (DIM)»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) under REMOVAL & INSTALLATION. When repairs are completed, go to step 8 .
  6. Repair open in circuit No. 731 (Gray wire). See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . When repairs are completed, go to next step.
  7. Check for an open or short in circuit No. 470 (Black wire). Repair as necessary. See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . When repairs are completed, go to next step.
  8. Using scan tool, clear all DTCs. Operate vehicle within conditions that set DTC. See «CONDITIONS FOR SETTING DTC»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . If DTC resets, go to step 2 . If DTC does not reset, system is operating properly.
  1. Perform diagnostic system check. If diagnostic system check has not been performed, see «DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville__hvac-diagnostic-system-check) . If diagnostic system check has been performed, go to next step.
  2. Install a scan tool. Turn ignition on, with engine off. Using scan tool, observe EVAPORATOR TEMP. parameter in Dash Integration Module (DIM) A/C INFORMATION data list. If scan tool indicates EVAPORATOR TEMP. parameter is -34°F to 261°F (-37°C to 127°C), check wiring harness connectors for intermittent and poor connections. Repair as necessary. See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . If no problems are found, go to next step.
  3. Turn ignition off. Disconnect A/C refrigerant low temperature sensor. Turn ignition on, with engine off. Using scan tool, observe EVAPORATOR TEMP. parameter in DIM A/C INFORMATION data list. If scan tool indicates EVAPORATOR TEMP. parameter is more than 261°F (127°C), go to next step. If indicated parameter is not more than 261°F (127°C), go to step 5 .
  4. Turn ignition off. Connect a 3-amp fused jumper wire between A/C refrigerant low temperature sensor connector terminals. Turn ignition on, with engine off. Using scan tool, observe EVAPORATOR TEMP. parameter in DIM A/C INFORMATION data list. If scan tool indicates EVAPORATOR TEMP. parameter is less than -34°F (-37°C), go to step 8 . If indicated parameter is not less than -34°F (-37°C), go to step 6 .
  5. Check for a short to ground in Gray wire between A/C refrigerant low temperature sensor and DIM 24-pin Light Blue connector C2 terminal A7. See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . Repair as necessary. If no problems are found, go to step 9 . When repairs are completed, go to step 12 .
  6. Check for a short to voltage, high resistance, or an open in Black wire between A/C refrigerant low temperature sensor and DIM 24-pin Light Blue connector C2 terminal A6. See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . Repair as necessary. If no problems are found, go to next step. When repairs are completed, go to step 12 .
  7. Check for high resistance or an open in Gray wire between A/C refrigerant low temperature sensor and DIM 24-pin Light Blue connector C2 terminal A7. See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . Repair as necessary. If no problems are found, go to step 9 . When repairs are completed, go to step 12 .
  8. Check A/C refrigerant low temperature sensor connector for loose or broken terminals. Repair as necessary. If no problems are found, go to step 10 . When repairs are completed, go to step 12 .
  9. Check DIM connector for loose or broken terminals. Repair as necessary. If no problems are found, go to step 11 . When repairs are completed, go to step 12 .
  10. Replace A/C refrigerant low temperature sensor. See «SENSORS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) under REMOVAL & INSTALLATION. When repairs are completed, go to step 12 .
  11. Replace IPM. See «HVAC CONTROL PANEL»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) under REMOVAL & INSTALLATION. When repairs are completed, go to next step.
  12. Using scan tool, clear all DTCs. Operate vehicle within conditions that set DTC. See «CONDITIONS FOR SETTING DTC»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . If DTC resets, go to step 2 . If DTC does not reset, system is operating properly.

On 2000 models, A/C refrigerant pressure sensor is a located in HVAC system high pressure side. Powertrain Control Module (PCM) and the Dash Integration Module (DIM) use A/C pressure sensor to monitor HVAC system pressure. DIM uses HVAC system pressure information to activate engine cooling fans when A/C pressure is high and to keep compressor disengaged when HVAC system pressure is excessively high. PCM supplies a 5-volt reference and a sensor ground. PCM monitors A/C refrigerant pressure circuit and determines whether or not signal is out of sensor range.

On 2001 models, Powertrain Control Module (PCM) monitors high side refrigerant pressure through an A/C refrigerant pressure sensor. When pressure is high, signal voltage is high. When pressure is low, signal voltage is low. When pressure is high, PCM activates cooling fans. When pressure is too high or too low, PCM will not allow A/C compressor clutch to engage. PCM sends A/C pressure data to Dash Integration Module (DIM) over Class 2 serial data circuits. DIM will not request A/C compressor clutch engagement if HVAC system pressure is too high.

On 2000 models, PCM will set a DTC when signal is out of range for a specific period of time. DIM will set DTC B1324 when HVAC system pressure is more than 430 psi (30.2 kg/cm 2 ), engine is operating and A/C compressor operation is requested. When DTC is set, A/C compressor clutch will not engage and PCM will not illuminate Malfunction Indicator Lamp (MIL).

On 2001 models, DTC will set when engine is operating, A/C operation has been requested and HVAC system refrigerant pressure sensor signal is more than 250 counts (4.90 volts) for 3 seconds. When DTC sets, PCM will not illuminate Malfunction Indicator Lamp (MIL). PCM will store conditions present when DTC set as FAIL RECORDS data only.

Clearing DTC

On 2000 models, DTC can be cleared using a scan tool. A history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction. A current DTC will clear when diagnostic operates and does not fail, battery voltage for DIM is interrupted or A/C pressure decreases to 201 psi (14.1 kg/cm 2 ).

On 2001 models, history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction. Current DTC can be cleared by using a scan tool to clear DTC INFORMATION FUNCTION.

Diagnostic Aids

On 2000 models, check for the following

  1. A malfunction within refrigerant system causing high pressure.
  2. A poor PCM connection.
  3. A damaged wiring harness.
  4. If wiring harness is okay, use scan tool to observe A/C pressure display. Move connectors and wiring harnesses related to A/C pressure sensor. A change in A/C pressure display will indicate location of malfunction.
  1. Perform diagnostic system check. If diagnostic system check has not been performed, see «DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville__hvac-diagnostic-system-check) . If diagnostic system check has been performed, go to next step.
  2. Install scan tool. Start engine and allow to idle. Turn A/C off. Select DIM data. Observe A/C pressure status. Turn A/C on. If A/C pressure status is high, go to next step. If A/C pressure status is not high, check wiring harness connectors for intermittent and poor connections. Repair as necessary. See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) .
  3. Using an A/C pressure gauge set and a scan tool, observe HVAC system pressures. If HVAC system pressures displayed on scan tool and gauge set are within 10 psi (0.70 kg/cm 2 ), go to next step. If pressures displayed are not within 10 psi (0.70 kg/cm 2 ), see INSUFFICIENT COOLING in MANUAL A/C-HEATER SYSTEMS - TROUBLE SHOOTING article.
  4. Using scan tool, observe A/C pressure status. Disconnect A/C refrigerant pressure sensor. If pressure status changes, go to next step. If pressure status does not change, go to step 6 .
  5. Check A/C refrigerant pressure sensor connector for loose or damaged terminals. Repair as necessary. If terminal contacts is okay, replace A/C refrigerant pressure sensor. See «SENSORS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) under REMOVAL & INSTALLATION. When repairs are completed, go to step 7 .
  6. Ensure DIM connector terminals are clean and tight. Repair as necessary. If terminal contacts is okay, replace DIM. See «DASH INTEGRATION MODULE (DIM)»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) under REMOVAL & INSTALLATION. When repairs are completed, go to next step.
  7. Using scan tool, clear all DTCs. Operate vehicle within conditions that set DTC. See «CONDITIONS FOR SETTING DTC»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . If DTC resets, go to step 2 . If DTC does not reset, system is operating properly.
  1. Perform diagnostic system check. If diagnostic system check has not been performed, see «DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville__hvac-diagnostic-system-check) . If diagnostic system check has been performed, go to next step.
  2. Install a scan tool. Turn ignition on, with engine off. Using scan tool, observe A/C HIGH SIDE PRESSURE parameter in POWERTRAIN, ENGINE DATA 2 list. If scan tool indicates that A/C HIGH SIDE PRESSURE parameter is 0.09-4.90 volts, check wiring harness connectors for intermittent and poor connections. Repair as necessary. See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . If indicated A/C HIGH SIDE PRESSURE parameter is not 0.09-4.90 volts, go to next step.
  3. Turn ignition off. Disconnect A/C refrigerant pressure sensor. Turn ignition on, with engine off. Using scan tool, observe A/C HIGH SIDE PRESSURE parameter. If scan tool indicates that A/C HIGH SIDE PRESSURE parameter is less than 0.09 volt, go to next step. If indicated parameter is more than 0.09 volt, go to step 10 .
  4. Turn ignition off. Connect a 3-amp fused jumper wire between A/C refrigerant pressure sensor connector terminals "B" (Gray wire) and "C" (Red/Black wire). Turn ignition on, with engine off. Using scan tool, observe A/C HIGH SIDE PRESSURE parameter. If scan tool indicates that A/C HIGH SIDE PRESSURE parameter is more than 4.90 volts, go to next step. If indicated parameter is less than 4.90 volts, go to step 8 .
  5. Disconnect fused jumper wire. Measure voltage between A/C refrigerant pressure sensor connector terminals "A" (Black wire) and "B" (Gray wire). If voltage is less than 5.1 volts, go to next step. If voltage is more than 5.1 volts, go to step 7 .
  6. Turn ignition off. Disconnect negative battery cable. Measure resistance between ground and A/C refrigerant pressure sensor connector terminal "B" (Gray wire). If resistance is less than 5 ohms, go to step 12 . If resistance is more than 5 ohms, go to step 11 .
  7. Check Gray wire for a short to voltage between A/C refrigerant pressure sensor and PCM. See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . Repair as necessary. If no problems are found, go to step 13 . When repairs are completed, go to step 16 .
  8. Check for a short to ground, a high resistance, or an open in Gray wire between A/C refrigerant pressure sensor and PCM. See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . Repair as necessary. If no problems are found, go to next step. When repairs are completed, go to step 16 .
  9. Check for a short to ground, high resistance, or an open in Red/Black wire between A/C refrigerant pressure sensor and PCM. See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . Repair as necessary. If no problems are found, go to step 13 . When repairs are completed, go to step 16 .
  10. Check for a short to voltage in Red/Black wire between A/C refrigerant pressure sensor and PCM 80-pin Clear connector C2 terminal No. 57. See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . Repair as necessary. If no problems are found, go to step 13 . When repairs are completed, go to step 16 .
  11. Turn ignition off. Disconnect PCM 80-pin Clear connector C2. Check Black wire for high resistance or an open between A/C refrigerant pressure sensor and PCM connector C2 terminal No. 14. See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . Repair as necessary. If no problems are found, go to step 13 . When repairs are completed, go to step 16 .
  12. Check A/C refrigerant pressure sensor connector for loose or damaged terminals. Repair as necessary. If terminal contacts is okay, go to step 14 . When repairs are completed, go to step 16 .
  13. Check PCM connector for loose or damaged terminals. Repair as necessary. If terminal contacts is okay, go to step 15 . When repairs are completed, go to step 16 .
  14. Replace A/C refrigerant pressure sensor. See «SENSORS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) under REMOVAL & INSTALLATION. When repairs are completed, go to step 16 .
  15. Replace PCM. See appropriate SELF-DIAGNOSTICS article in ACCESSORIES & EQUIPMENT. When repairs are completed, go to next step.
  16. Using scan tool, clear all DTCs. Operate vehicle within conditions that set DTC. See «CONDITIONS FOR SETTING DTC»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . If DTC resets, go to step 2 . If DTC does not reset, system is operating properly.

On 2000 models, left A/C temperature sensor is a thermistor that controls signal voltage to Instrument Panel Integration Module (IPM). IPM supplies voltage on circuit No. 516. When sensor is cold, resistance increases and IPM will sense a high signal voltage at connector C2 terminal B6 (Black wire). When sensor warms, resistance decreases and signal voltage is pulled low through circuit No. 61 (Yellow wire). Signal voltage will vary from 5.0 volts (open circuit) to zero volts (short circuit).

On 2001 models, HVAC control module (IPM) monitors left A/C duct air temperature through an upper left air temperature sensor. When air is cold, sensor resistance and signal voltage are high. When air is warm, sensor resistance and signal voltage are low. IPM requests A/C compressor clutch engagement and controls left air temperature actuator door positions in order to maintain selected air temperature on IPM display.

On 2000 models, DTC will set when ignition is on and an open or short is detected. When DTC sets, IPM uses a default value of 128 counts and 75°F (24°C) to allow HVAC system to operate. If air delivery is on A/C or bi-level, air mix (temperature) doors will cycle between full cold and full hot. DTC can be cleared using a scan tool or interrupting battery voltage to IPM. A current DTC will clear when diagnostic operates and does not fail.

On 2001 models, DTC will set when ignition is on and IPM detects a signal circuit that is less than 5 counts (0.09 volts) or more than 250 counts (4.90 volts). IPM will use a default value for sensor data. Scan tool displays default LEFT A/C DUCT TEMP value in IPM HVAC SENSORS data list. Scan tool displays actual LEFT A/C DUCT TEMP value in IPM OPEN/SHORT data list. DTC can be cleared using a scan tool. DTC will become history if IPM no longer detects a failure. History DTC will clear after 50 fault free ignition cycles.

  1. Perform diagnostic system check. If diagnostic system check has not been performed, see «DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville__hvac-diagnostic-system-check) . If diagnostic system check has been performed, go to next step.
  2. Turn ignition off. Disconnect left A/C air temperature sensor. Turn ignition on. Measure voltage between sensor harness connector terminals "A" (Black wire) and "B" (Yellow wire). If voltage is 5.0 volts, go to next step. If voltage is not 5.0 volts, go to step 4 .
  3. Turn ignition off. Reconnect left A/C temperature sensor. Connect scan tool. Turn ignition on. Clear DTC using scan tool. Start engine and allow to idle. If DTC resets, go to next step. If DTC does not reset, check wiring harness connectors for intermittent and poor connections. Repair as necessary. See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) .
  4. Using scan tool, select IPM open/short data. Display LH A/C TEMPERATURE data. Start engine and allow to idle. Disconnect left A/C temperature sensor. Left A/C temperature voltage should increase to 5.0 volts. Reconnect left A/C temperature sensor connector. If left A/C temperature sensor voltage decreases, go to next step. If sensor voltage does not decrease, go to step 6 .
  5. Replace left A/C temperature sensor. See «SENSORS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) under REMOVAL & INSTALLATION. When repairs are completed, go to step 9 .
  6. Check circuit No. 61 (Yellow wire) for an open or short. If Yellow wire is okay, go to next step. If Yellow wire is not okay, go to step 8 .
  7. Check circuit No. 561 (Black wire) for an open or short. Repair as necessary. If Black wire is okay, replace IPM. See «HVAC CONTROL PANEL»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) under REMOVAL & INSTALLATION. When repairs are completed, go to step 9 .
  8. Repair open or short in circuit No. 61 (Yellow wire). See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . When repairs are completed, go to next step.
  9. Using scan tool, clear all DTCs. Operate vehicle within conditions that set DTC. See «CONDITIONS FOR SETTING DTC»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . If DTC resets, go to step 2 . If DTC does not reset, system is operating properly.
  1. Perform diagnostic system check. If diagnostic system check has not been performed, see «DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville__hvac-diagnostic-system-check) . If diagnostic system check has been performed, go to next step.
  2. Install a scan tool. Turn ignition on, with engine off. Using scan tool, observe LEFT A/C DUCT TEMP parameter in IPM OPEN/SHORT data list. If scan tool indicates that LEFT AC DUCT TEMP parameter is 5-250 counts (0.09-4.90 volts), check wiring harness connectors for intermittent and poor connections. See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . Repair as necessary. If indicated parameter is not 5-250 counts (0.09-4.90 volts), go to next step.
  3. Turn ignition off. Disconnect upper left air temperature sensor. Turn ignition on, with engine off. Using scan tool, observe LEFT AC DUCT TEMP parameter in IPM OPEN/SHORT data list. If scan tool indicates that LEFT AC DUCT TEMP parameter is more than 250 counts (4.90 volts), go to next step. If indicated parameter is less than 250 counts (4.90 volts), go to step 5 .
  4. Turn ignition off. Connect a 3-amp fused jumper wire between upper left air temperature sensor connector terminals "A" (Black wire) and "B" (Yellow wire). Turn ignition on, with engine off. Using scan tool, observe LEFT A/C DUCT TEMP parameter in IPM OPEN/SHORT data list. If scan tool indicates that LEFT A/C DUCT TEMP parameter is less than 5 counts (0.09 volts), go to step 8 . If indicated parameter is not less than 5 counts (0.09 volts), go to step 6 .
  5. Check for a short to ground in Black wire between upper left air temperature sensor and IPM 24-pin connector C2 terminal B6. See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . Repair as necessary. If Black wire is okay, go to step 9 . When repairs are completed, go to step 12 .
  6. Check for a short to voltage, high resistance, or an open in Black wire between upper left air temperature sensor and IPM 24-pin connector C2 terminal B6. See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . Repair as necessary. If Black wire is okay, go to next step. When repairs are completed, go to step 12 .
  7. Check for high resistance or an open in Yellow wire between upper left air temperature sensor and IPM 24-pin connector terminal B8. See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . Repair as necessary. If Yellow wire is okay, go to step 9 . When repairs are completed, go to step 12 .
  8. Check connector for loose or damaged terminals at upper left air temperature sensor connector. See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . Repair as necessary. If no problems are found, go to step 10 . When repairs are completed, go to step 12 .
  9. Check connector for loose or damaged terminals at IPM 24-pin connector C2. Repair as necessary. If no problems are found, go to step 11 . When repairs are completed, go to step 12 .
  10. Replace upper left air temperature sensor. See «SENSORS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) under REMOVAL & INSTALLATION. When repairs are completed, go to step 12 .
  11. IPM. See «HVAC CONTROL PANEL»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) under REMOVAL & INSTALLATION. When repairs are completed, go to next step.
  12. Using scan tool, clear all DTCs. Operate vehicle within conditions that set DTC. See «CONDITIONS FOR SETTING DTC»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . If DTC resets, go to step 2 . If DTC does not reset, system is operating properly.

On 2000 models, right A/C temperature sensor is a thermistor that controls signal voltage to Instrument Panel Integration Module (IPM). IPM supplies voltage on circuit No. 517. When sensor is cold, resistance increases and IPM will sense a high signal voltage at connector C2 terminal B7 (Tan wire). When sensor warms, resistance decreases and signal voltage is pulled low through circuit No. 61 (Yellow wire). Signal voltage will vary from 5.0 volts (open circuit) to zero volts (short circuit).

On 2001 models, HVAC control module (IPM) monitors right A/C duct air temperature through an upper right air temperature sensor. When air is cold, sensor resistance and signal voltage are high. When air is warm, sensor resistance and signal voltage are low. IPM requests A/C compressor clutch engagement and controls right air temperature actuator door positions in order to maintain selected air temperature on IPM display.

On 2000 models, DTC will set when ignition is on and an open or short is detected. When DTC sets, IPM uses a default value of 128 counts and 75°F (24°C) to allow HVAC system to operate. If air delivery is on A/C or bi-level, air mix (temperature) doors will cycle between full cold and full hot. DTC can be cleared using a scan tool or interrupting battery voltage to IPM. A current DTC will clear when diagnostic operates and does not fail.

On 2001 models, DTC will set when ignition is on and IPM detects a signal circuit that is less than 5 counts (0.09 volts) or more than 250 counts (4.90 volts). IPM will use a default value for sensor data. Scan tool displays default LEFT A/C DUCT TEMP value in IPM HVAC SENSORS data list. Scan tool displays actual LEFT A/C DUCT TEMP value in IPM OPEN/SHORT data list. DTC can be cleared using a scan tool. DTC will become history if IPM no longer detects a failure. History DTC will clear after 50 fault free ignition cycles.

  1. Perform diagnostic system check. If diagnostic system check has not been performed, see «DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville__hvac-diagnostic-system-check) . If diagnostic system check has been performed, go to next step.
  2. Turn ignition off. Disconnect right A/C air temperature sensor. Turn ignition on. Measure voltage between sensor harness connector terminals "A" (Tan wire) and "B" (Yellow wire). If voltage is 5.0 volts, go to next step. If voltage is not 5.0 volts, go to step 4 .
  3. Turn ignition off. Reconnect right A/C temperature sensor. Connect scan tool. Turn ignition on. Clear DTC using scan tool. Start engine and allow to idle. If DTC resets, go to next step. If DTC does not reset, check wiring harness connectors for intermittent and poor connections. Repair as necessary. See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) .
  4. Using scan tool, select IPM open/short data. Display RH A/C TEMPERATURE data. Start engine and allow to idle. Disconnect right A/C temperature sensor. Right A/C temperature voltage should increase to 5.0 volts. Reconnect right A/C temperature sensor connector. If right A/C temperature sensor voltage decreases, go to next step. If sensor voltage does not decrease, go to step 6 .
  5. Replace right A/C temperature sensor. See «SENSORS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) under REMOVAL & INSTALLATION. When repairs are completed, go to step 9 .
  6. Check circuit No. 61 (Yellow wire) for an open or short. If Yellow wire is okay, go to next step. If Yellow wire is not okay, go to step 8 .
  7. Check circuit No. 517 (Tan wire) for an open or short. Repair as necessary. If Tan wire is okay, replace IPM. See «HVAC CONTROL PANEL»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) under REMOVAL & INSTALLATION. When repairs are completed, go to step 9 .
  8. Repair open or short in circuit No. 61 (Yellow wire). See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . When repairs are completed, go to next step.
  9. Using scan tool, clear all DTCs. Operate vehicle within conditions that set DTC. See «CONDITIONS FOR SETTING DTC»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . If DTC resets, go to step 2 . If DTC does not reset, system is operating properly.
  1. Perform diagnostic system check. If diagnostic system check has not been performed, see «DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville__hvac-diagnostic-system-check) . If diagnostic system check has been performed, go to next step.
  2. Install a scan tool. Turn ignition on, with engine off. Using scan tool, observe RIGHT AC DUCT TEMP parameter in IPM OPEN/SHORT data list. If scan tool indicates that RIGHT AC DUCT TEMP parameter is 5-250 counts (0.09-4.90 volts), check wiring harness connectors for intermittent and poor connections. Repair as necessary. See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . If indicated parameter is not 5-250 counts (0.09-4.90 volts), go to next step.
  3. Turn ignition off. Disconnect upper right air temperature sensor. Turn ignition on, with engine off. Using scan tool, observe RIGHT AC DUCT TEMP parameter in IPM OPEN/SHORT data list. If scan tool indicates that RIGHT AC DUCT TEMP parameter is more than 250 counts (4.90 volts), go to next step. If indicated parameter is not more than 250 counts (4.90 volts), go to step 5 .
  4. Turn ignition off. Connect a 3-amp fused jumper wire between upper right air temperature sensor connector terminals "A" (Tan wire) and "B" (Yellow wire). Turn ignition on, with engine off. Using scan tool, observe RIGHT A/C DUCT TEMP parameter in IPM OPEN/SHORT data list. If scan tool indicates that RIGHT A/C DUCT TEMP parameter is less 5 counts (0.09 volts), go to step 8 . If indicated parameter is not less than 5 counts (0.09 volts), go to step 6 .
  5. Check for a short to ground in Tan wire between upper right air temperature sensor and IPM connector C2 terminal B7. See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . Repair as necessary. If Tan wire is okay, go to step 9 . When repairs are completed, go to step 12 .
  6. Check for a short to voltage, high resistance, or an open in Tan wire between upper right air temperature sensor and IPM. Repair as necessary. If Tan wire is okay, go to next step. When repairs are completed, go to step 12 .
  7. Check for high resistance or an open in Yellow wire between upper right air temperature sensor and IPM. Repair as necessary. If Yellow wire is okay, go to step 9 . When repairs are completed, go to step 12 .
  8. Check for poor connections at upper right air temperature sensor harness connector. See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . Repair as necessary. If connections are okay, go to step 10 . When repairs are completed, go to step 12 .
  9. Check for poor connections at IPM harness connector. See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . Repair as necessary. If connections are okay, go to step 11 . When repairs are completed, go to step 12 .
  10. Replace upper right air temperature sensor. See «SENSORS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) under REMOVAL & INSTALLATION. When repairs are completed, go to step 12 .
  11. Replace IPM. See «HVAC CONTROL PANEL»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) under REMOVAL & INSTALLATION. When repairs are completed, go to next step.
  12. Using scan tool, clear all DTCs. Operate vehicle within conditions that set DTC. See «CONDITIONS FOR SETTING DTC»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . If DTC resets, go to step 2 . If DTC does not reset, system is operating properly.

On 2000 models, left heater temperature sensor is a thermistor that controls signal voltage to Instrument Panel Integration Module (IPM). IPM supplies voltage on circuit No. 518. When sensor is cold, resistance increases and IPM will sense a high signal voltage at connector C2 terminal B9 (Black wire). When sensor warms, resistance decreases and signal voltage is pulled low through circuit No. 61 (Yellow wire). Signal voltage will vary from 5.0 volts (open circuit) to zero volts (short circuit).

On 2001 models, HVAC control module (IPM) monitors left heater duct air temperature through a lower left air temperature sensor. When air is cold, sensor resistance and signal voltage are high. When air is warm, sensor resistance and signal voltage are low. IPM controls left air temperature actuator door position in order to maintain selected air temperature on IPM display.

On 2000 models, DTC will set when ignition is on and an open or short is detected. When DTC sets, IPM uses a default value of 128 counts and 75°F (24°C) to allow HVAC system to operate. If air delivery is heater, defog or defrost air mix door will cycle between full hot and full cold. DTC can be cleared using a scan tool or interrupting battery voltage to IPM. A current DTC will clear when diagnostic operates and does not fail.

On 2001 models, DTC will set when ignition is on and IPM detects a signal circuit that is less than 5 counts (0.09 volts) or more than 250 counts (4.90 volts). IPM will use a default value for sensor data. Scan tool displays DEFAULT DRIVER HTR. DUCT TEMP value in IPM HVAC SENSORS data list. Scan tool displays actual DEFAULT DRIVER HTR. DUCT TEMP value in IPM OPEN/SHORT data list. DTC can be cleared using a scan tool. DTC will become history if IPM no longer detects a failure. History DTC will clear after 50 fault free ignition cycles.

  1. Perform diagnostic system check. If diagnostic system check has not been performed, see «DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville__hvac-diagnostic-system-check) . If diagnostic system check has been performed, go to next step.
  2. Turn ignition off. Disconnect left heater air temperature sensor. Turn ignition on. Measure voltage between sensor harness connector terminals "A" (Black wire) and "B" (Yellow wire). If voltage is 5.0 volts, go to next step. If voltage is not 5.0 volts, go to step 4 .
  3. Turn ignition off. Reconnect left heater temperature sensor. Connect scan tool. Turn ignition on. Clear DTC using scan tool. Start engine and allow to idle. If DTC resets, go to next step. If DTC does not reset, check wiring harness connectors for intermittent and poor connections. Repair as necessary. See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) .
  4. Using scan tool, select IPM open/short data. Display LH INSIDE TEMPERATURE data. Start engine and allow to idle. Disconnect left inside temperature sensor. Left inside temperature voltage should increase to 5.0 volts. Reconnect left inside temperature sensor connector. If left inside temperature sensor voltage decreases, go to next step. If sensor voltage does not decrease, go to step 6 .
  5. Replace left heater temperature sensor. See «SENSORS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) under REMOVAL & INSTALLATION. When repairs are completed, go to step 9 .
  6. Check circuit No. 61 (Yellow wire) for an open or short. If Yellow wire is okay, go to next step. If Yellow wire is not okay, go to step 8 .
  7. Check circuit No. 518 (Black wire) for an open or short. Repair as necessary. If Black wire is okay, replace IPM. See «HVAC CONTROL PANEL»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) under REMOVAL & INSTALLATION. When repairs are completed, go to step 9 .
  8. Repair open or short in circuit No. 61 (Yellow wire). See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . When repairs are completed, go to next step.
  9. Using scan tool, clear all DTCs. Operate vehicle within conditions that set DTC. See «CONDITIONS FOR SETTING DTC»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . If DTC resets, go to step 2 . If DTC does not reset, system is operating properly.
  1. If diagnostic system check has not been performed, see «DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville__hvac-diagnostic-system-check) . If diagnostic system check has been performed, go to next step.
  2. Install a scan tool. Turn ignition on, with engine off. Using scan tool, observe LEFT HTR. DUCT TEMP. parameter in IPM OPEN/SHORT data list. If scan tool indicates that LEFT HTR. DUCT TEMP. parameter is 5-250 counts (0.09-4.90 volts), check wiring harness connectors for intermittent and poor connections. Repair as necessary. See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . If indicated parameter is not 5-250 counts (0.09-4.90 volts), go to next step.
  3. Turn ignition off. Disconnect lower left air temperature sensor. Turn ignition on, with engine off. Using scan tool, observe LEFT HTR. DUCT TEMP. parameter in IPM OPEN/SHORT data list. If scan tool indicates that LEFT HTR. DUCT TEMP. parameter is more than 250 counts (4.90 volts), go to next step. If indicated parameter is not more 250 counts (4.90 volts), go to step 5 .
  4. Turn ignition off. Connect a 3-amp fused jumper wire between lower left air temperature sensor connector terminals. Turn ignition on, with engine off. Using scan tool, observe LEFT HTR. DUCT TEMP. parameter in IPM OPEN/SHORT data list. If scan tool indicates that LEFT HTR. DUCT TEMP. parameter is less than 5 counts (0.09 volts), go to step 8 . If indicated parameter is not less than 5 counts (0.09 volts), go to step 6 .
  5. Check for a short to ground in Black wire between lower left air temperature sensor and IPM. See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . Repair as necessary. If Black wire is okay, go to step 9 . When repairs are completed, go to step 12 .
  6. Check for a short to voltage, high resistance, or an open in Black wire between lower left air temperature sensor and IPM. See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . Repair as necessary. If Black wire is okay, go to next step. When repairs are completed, go to step 12 .
  7. Check for a high resistance or an open in Yellow/Black wire between lower left air temperature sensor and IPM. See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . Repair as necessary. If Yellow/Black wire is okay, go to step 9 . When repairs are completed, go to step 12 .
  8. Check for poor connections at lower left air temperature sensor harness connector. See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . Repair as necessary. If connections are okay, go to step 10 . When repairs are completed, go to step 12 .
  9. Check for poor connections at IPM harness connector C2. See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . Repair as necessary. If connections are okay, go to step 11 . When repairs are completed, go to step 12 .
  10. Replace lower left air temperature sensor. See «SENSORS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) under REMOVAL & INSTALLATION. When repairs are completed, go to step 12 .
  11. Replace IPM. See «HVAC CONTROL PANEL»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) under REMOVAL & INSTALLATION. When repairs are completed, go to next step.
  12. Using scan tool, clear all DTCs. Operate vehicle within conditions that set DTC. See «CONDITIONS FOR SETTING DTC»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . If DTC resets, go to step 2 . If DTC does not reset, system is operating properly.

On 2000 models, right heater temperature sensor is a thermistor that controls signal voltage to the Instrument Panel Integration Module (IPM). IPM supplies voltage on circuit No. 520. When sensor is cold, resistance increases and IPM will sense a high signal voltage at connector C1 terminal D3 (Black wire). When sensor warms, resistance decreases and signal voltage is pulled low through circuit No. 61. Signal voltage will vary from 5.0 volts (open circuit) to zero volts (short circuit).

On 2001 models, HVAC control module (IPM) monitors right heater duct air temperature through a lower right air temperature sensor. When air is cold, sensor resistance and signal voltage are high. When air is warm, sensor resistance and signal voltage are low. IPM controls right air temperature actuator door position in order to maintain selected air temperature on IPM display.

On 2000 models, DTC will set when ignition is on and an open or short is detected. When DTC sets, IPM uses a default value of 128 counts and 75°F (24°C) to allow HVAC system to operate. If air delivery is heater, defog or defrost air mix door will cycle between full hot and full cold. DTC can be cleared using a scan tool or interrupting battery voltage to IPM. A current DTC will clear when diagnostic operates and does not fail.

On 2001 models, DTC will set when ignition is on and IPM detects a signal circuit that is less than 5 counts (0.09 volts) or more than 250 counts (4.90 volts). IPM will use a default value for sensor data. Scan tool displays DEFAULT PASSENGER HTR. DUCT TEMP value in IPM HVAC SENSORS data list. Scan tool displays actual DEFAULT PASSENGER HTR. DUCT TEMP value in IPM OPEN/SHORT data list. DTC can be cleared using a scan tool. DTC will become history if IPM no longer detects a failure. History DTC will clear after 50 fault free ignition cycles.

  1. Perform diagnostic system check. If diagnostic system check has not been performed, see «DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville__hvac-diagnostic-system-check) . If diagnostic system check has been performed, go to next step.
  2. Turn ignition off. Disconnect sensor connector. Turn ignition on. Measure voltage between sensor harness connector terminal "A" (Black wire) and "B" (Yellow wire). If voltage is 5.0 volts, go to next step. If voltage is not 5.0 volts, go to step 4 .
  3. Turn ignition off. Reconnect sensor connector. Connect scan tool. Turn ignition on. Using scan tool, clear DTC. Start engine and allow to idle. If DTC resets, go to next step. If DTC does not reset, check wiring harness connectors for intermittent and poor connections. Repair as necessary. See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) .
  4. Using scan tool, select IPM open/short data. Display RH INSIDE TEMPERATURE data. Start engine and allow to idle. Disconnect right inside temperature sensor. Right inside temperature voltage should increase to 5.0 volts. Reconnect right inside temperature sensor connector. If right inside temperature sensor voltage decreases, go to next step. If sensor voltage does not decrease, go to step 6 .
  5. Replace right heater temperature sensor. See «SENSORS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) under REMOVAL & INSTALLATION. When repairs are completed, go to step 9 .
  6. Check circuit No. 61 (Yellow wire) for an open or short. See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . If Yellow wire is okay, go to next step. If Yellow wire is not okay, go to step 8 .
  7. Check circuit No. 520 (Black wire) for an open or short . If Black wire is okay, replace IPM. See «HVAC CONTROL PANEL»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) under REMOVAL & INSTALLATION. When repairs are completed, go to step 9 .
  8. Repair open or short in circuit No. 61 (Yellow wire). See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . When repairs are completed, go to next step.
  9. Using scan tool, clear all DTCs. Operate vehicle within conditions that set DTC. See «CONDITIONS FOR SETTING DTC»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . If DTC resets, go to step 2 . If DTC does not reset, system is operating properly.
  1. Perform diagnostic system check. If diagnostic system check has not been performed, see «DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville__hvac-diagnostic-system-check) . If diagnostic system check has been performed, go to next step.
  2. Install a scan tool. Turn ignition on, with engine off. Using scan tool, observe RIGHT HTR. DUCT TEMP. parameter in IPM OPEN/SHORT data list. If scan tool indicates that RIGHT HTR. DUCT TEMP. parameter is 5-250 counts (0.09-4.90 volts), check wiring harness connectors for intermittent and poor connections. Repair as necessary. See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . If indicated parameter is not 5-250 counts (0.09-4.90 volts), go to next step.
  3. Turn ignition off. Disconnect lower right air temperature sensor. Turn ignition on, with engine off. Using scan tool, observe RIGHT HTR. DUCT TEMP. parameter in IPM OPEN/SHORT data list. If scan tool indicates that RIGHT HTR. DUCT TEMP. parameter is more than 250 counts (4.90 volts), go to next step. If indicated parameter is not more than 250 counts (4.90 volts), go to step 5 .
  4. Turn ignition off. Connect a 3-amp fused jumper wire between lower right air temperature sensor connector terminals "A" (Black wire) and "B" (Yellow wire). Turn ignition on, with engine off. Using scan tool, observe RIGHT HTR. DUCT TEMP. parameter in IPM OPEN/SHORT data list. If scan tool indicates that RIGHT HTR. DUCT TEMP. parameter is less than 5 counts (0.09 volts), go to step 8 . If indicated parameter is not less than 5 counts (0.09 volts), go to step 6 .
  5. Check for a short to ground in Black wire between lower right air temperature sensor and IPM. See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . Repair as necessary. If Black wire is okay, go to step 9 . When repairs are completed, go to step 12 .
  6. Check for a short to voltage, a high resistance, or an open in Black wire between lower right air temperature sensor and IPM. See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . Repair as necessary. If Black wire is okay, go to next step. When repairs are completed, go to step 12 .
  7. Check for a high resistance or an open in Yellow wire between lower right air temperature sensor and IPM. See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . Repair as necessary. If Black wire is okay, go to step 9 . When repairs are completed, go to step 12 .
  8. Check for poor connections at lower right air temperature sensor harness connector. See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . Repair as necessary. If connections are okay, go to step 10 . When repairs are completed, go to step 12 .
  9. Check for poor connections at IPM harness connector C1. See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . Repair as necessary. If connections are okay, go to step 11 . When repairs are completed, go to step 12 .
  10. Replace lower right air temperature sensor. See «SENSORS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) under REMOVAL & INSTALLATION. When repairs are completed, go to step 12 .
  11. Replace IPM. See «HVAC CONTROL PANEL»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) under REMOVAL & INSTALLATION. When repairs are completed, go to next step.
  12. Using scan tool, clear all DTCs. Operate vehicle within conditions that set DTC. See «CONDITIONS FOR SETTING DTC»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . If DTC resets, go to step 2 . If DTC does not reset, system is operating properly.

On 2000 models, rear fuse junction block supplies ignition voltage through circuit No. 141 (Brown wire). IPM commands actuator to move by suppling voltage on command line circuit No. 1199 (Dark Blue wire). A zero volts signal moves door toward full cold. A 2.5 volts signal stops door movement. A 5.0 volt signal moves door toward full hot. IPM determines current door position by monitoring feedback voltage on circuit No. 733 (Light Blue wire). A feedback potentiometer supplies a regulated 5.0 volt signal on circuit No. 705 (Gray wire), and a ground from IPM circuit No. 1791 (Yellow wire). Door is gear driven inside actuator. Feedback voltage is a function of motor position with 4.0-5.0 volts indicating full cold door position and less then one volt indicating full hot position. Operation of air mix door actuator can be evaluated using scan tool data.

On 2001 models, HVAC control module (IPM) commands left air temperature actuator to move by controlling voltage supplied on control circuit. A voltage of zero volts moves door toward full cold. A voltage of 2.5 volts stops door movement. A voltage of 5.0 volts moves door toward full hot. IPM determines current door position by monitoring signal circuit voltage. Feedback potentiometer is a function of motor position. A voltage of 4.0-5.0 volts indicates full hot door position. A voltage of less than one volt indicates full hot door position. IPM controls left air temperature actuator door positions in order to maintain selected air temperature.

On 2000 models, DTC will set when ignition is on and feedback circuit is open or shorted. When DTC sets, IPM will use a default value of 128 counts. This default value results in only 2 door positions: full hot and full cold. DTC can be cleared using a scan tool or interrupting IPM battery voltage. A current DTC will clear when diagnostic operates and does not fail.

On 2001 models, DTC will set when ignition is on and IPM detects a signal circuit that is less than 5 counts (0.09 volts) or more than 250 counts (4.90 volts). When DTC sets, IPM will use a default value for sensor data in an attempt to maintain air temperature selected by driver. DTC will become history if IPM no longer detects a failure. History DTC will clear after 50 fault free ignition cycles. DTC can be cleared using a scan tool.

  1. Perform diagnostic system check. If diagnostic system check has not been performed, see «DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville__hvac-diagnostic-system-check) . If diagnostic system check has been performed, go to next step.
  2. Install scan tool. Start engine and bring to normal operating temperature. Using scan tool, establish communications with IPM. Recalibrate all actuators. If difference between minimum and maximum counts is within 150-220 counts, go to next step. If difference between minimum and maximum counts is not within 150-220 counts, go to step 4 .
  3. Using scan tool, clear all DTCs. Operate HVAC system. If HVAC system operates normally, go to step 18 . If HVAC system does not operate normally, go to next step.
  4. Disconnect actuator electrical connector. Measure circuit No. 705 voltage at actuator connector terminal No. 10 (Gray wire). If voltage is 5.0 volts, go to next step. If voltage is not 5.0 volts, go to step 9 .
  5. Measure circuit No. 141 voltage at actuator connector terminal No. 5 (Brown wire). If voltage is 12.0 volts, go to next step. If voltage is not 12.0 volts, go to step 9 .
  6. Measure voltage between circuit No. 141, actuator connector terminal No. 5 (Brown wire) and circuit No. 1791, actuator connector terminal No. 7 (Yellow wire). If voltage is 12.0 volts, go to next step. If voltage is not 12.0 volts, go to step 9 .
  7. Measure circuit No. 1199 voltage at actuator connector terminal No. 6 (Dark Blue wire). If voltage is 2.5 volts, go to next step. If voltage is not 2.5 volts, go to step 9 .
  8. Measure circuit No. 733 voltage at actuator connector terminal No. 9 (Light Blue wire). If voltage is 5.0 volts, go to next step. If voltage is not 5.0 volts, go to step 11 .
  9. Check suspect circuits for an open or short. If a problem is located, go to next step. If a problem is not located, go to step 11 .
  10. Repair open or short condition. When repairs are completed, go to step 21 .
  11. Using scan tool, observe ACTUATOR data. If ACTUATOR actual data displayed is 255 counts (5.0 volts), go to next step. If ACTUATOR actual data displayed is not 255 counts (5.0 volts), go to step 20 .
  12. Using a fused jumper wire, connect circuit No. 733 at actuator connector terminal No. 9 (Light Blue wire) to ground. If ACTUATOR actual data displayed on scan tool is zero counts (zero volts), go to next step. If ACTUATOR actual data displayed on scan tool is not zero counts (zero volts), go to step 20 .
  13. Reconnect actuator connector. If ACTUATOR actual data displayed on scan tool is 255 counts or zero counts, go to step 20 . If ACTUATOR actual data displayed on scan tool is not 255 counts or zero counts, go to next step.
  14. Using scan tool. Move actuator to hot and cold positions. If actuator moves in both directions, go to next step. If actuator does not move in both directions, go to step 16 .
  15. If actuator actual position feedback changes, go to step 21 . If actuator actual position feedback does not change, go to step 19 .
  16. Using a fused jumper wire, connect circuit No. 705 at actuator connector terminal No. 10 (Gray wire) and circuit No. 199 at actuator connector terminal No. 6 (Dark Blue wire). If actuator moves, go to next step. If actuator does not move, go to step 18 .
  17. If actuator actual position feedback changes, go to step 21 . If actuator actual position feedback changes, go to step 19 .
  18. Using a fused jumper wire, connect circuit No. 1791 at actuator connector terminal No. 7 (Yellow wire) to circuit No. 1199 at actuator connect terminal No. 6 (Dark Blue wire). If actuator moves, go to step 17 . If actuator does not move, go to next step.
  19. Replace actuator. See «ACTUATORS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) under REMOVAL & INSTALLATION. When repairs are completed, go to step 21 .
  20. Replace IPM. See «HVAC CONTROL PANEL»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) under REMOVAL & INSTALLATION. When repairs are completed, go to next step.
  21. Using scan tool, clear all DTCs. Operate vehicle within conditions that set DTC. See «CONDITIONS FOR SETTING DTC»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . If DTC resets, go to step 2 . If DTC does not reset, system is operating properly.
  1. Perform diagnostic system check. If diagnostic system check has not been performed, see «DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville__hvac-diagnostic-system-check) . If diagnostic system check has been performed, go to next step.
  2. Install a scan tool. Turn ignition on, with engine off. Using scan tool, observe LEFT TEMP DR ACTUAL parameter in IPM HVAC DOOR POSITIONS data list. If scan tool indicates that LEFT TEMP DR ACTUAL parameter is 5-250 counts (0.09-4.90 volts), check for a disconnected or broken door. DTC sets because actuator traveled to its internal stops (overtravel condition). Check wiring harness connectors for intermittent and poor connections. Repair as necessary. See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . If indicated parameter is not 5-250 counts (0.09-4.90 volts), go to next step.
  3. Turn ignition off. Disconnect left air temperature actuator connector. Turn ignition on, with engine off. Using scan tool, observe LEFT TEMP DR ACTUAL parameter. If scan tool indicates that LEFT TEMP DR ACTUAL parameter is more than 250 counts (4.90 volts), go to next step. If indicated parameter is not more than 250 counts (4.90 volts), go to step 8 .
  4. Turn ignition off. Connect a 3-amp fused jumper wire between left air temperature actuator connector terminals No. 7 (Yellow wire) and No. 9 (Purple wire). Turn ignition on, with engine off. Using scan tool, observe LEFT TEMP DR ACTUAL parameter. If scan tool indicates that LEFT TEMP DR ACTUAL parameter is less than 5 counts (0.09 volts), go to next step. If indicated parameter is not 5 counts (0.09 volts), go to step 9 .
  5. Turn ignition off. Disconnect fused jumper wire. Connect a 3-amp fused jumper wire between left air temperature actuator connector terminals No. 9 (Purple wire) and No. 10 (Gray wire). Turn ignition on, with engine off. Using scan tool, observe LEFT TEMP DR ACTUAL parameter. If scan tool indicates that LEFT TEMP DR ACTUAL parameter is more than 250 counts (4.90 volts), go to step 7 . If indicated parameter is not 250 counts (4.90 volts), go to next step.
  6. Check for a short to ground in Gray wire between left air temperature actuator connector terminal No. 10 and IPM connector C2 terminal A1. Repair as necessary. See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . If Gray wire is okay, go to step 12 . When repairs are completed, go to step 15 .
  7. Check for a short to voltage, high resistance or an open in Gray wire between left air temperature actuator connector terminal No. 10 and IPM connector C2 terminal A1. Repair as necessary. See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . If Gray wire is okay, go to step 11 . When repairs are completed, go to step 15 .
  8. Check for a short to ground in Light Blue wire between left air temperature actuator connector terminal No. 9 and IPM connector C2 terminal A5. Repair as necessary. See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . If Light Blue wire is okay, go to step 12 . When repairs are completed, go to step 15 .
  9. Check for a short to voltage, high resistance, or an open in Light Blue wire between left air temperature actuator connector terminal No. 9 and IPM connector C2 terminal A5. Repair as necessary. See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . If Light Blue wire is okay, go to next step. When repairs are completed, go to step 15 .
  10. Check for a high resistance or an open in Yellow wire between left air temperature actuator connector terminal No. 7 and IPM connector C2 terminal A7. Repair as necessary. See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . If Yellow wire is okay, go to step 12 . When repairs are completed, go to step 15 .
  11. Check left air temperature actuator harness connector for loose or damaged terminals. Repair as necessary. See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . If connector terminals are clean and tight, go to step 13 . When repairs are completed, go to step 15 .
  12. Check IPM harness connector for loose or damaged terminals. Repair as necessary. See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . If connector terminals are clean and tight, go to step 14 . When repairs are completed, go to step 15 .
  13. Replace left air temperature actuator. See «ACTUATORS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) under REMOVAL & INSTALLATION. When repairs are completed, go to step 15 .
  14. Replace IPM. See «HVAC CONTROL PANEL»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) under REMOVAL & INSTALLATION. When repairs are completed, go to next step.
  15. Using scan tool, clear all DTCs. Operate vehicle within conditions that set DTC. See «CONDITIONS FOR SETTING DTC»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . If DTC resets, go to step 2 . If DTC does not reset, system is operating properly.

On 2000 models, rear fuse junction block supplies ignition voltage through circuit No. 141 (Brown wire). IPM commands actuator to move by suppling voltage on command line circuit No. 1236 (White/Black wire). A zero volts signal moves door toward full cold. A 2.5 volts signal stops door movement. A 5.0 volt signal moves door toward full hot. IPM determines current door position by monitoring feedback voltage on circuit No. 1646 (Dark Blue wire). A feedback potentiometer supplies a regulated 5.0 volt signal on circuit No. 705 (Gray wire), and a ground from IPM circuit No. 1791 (Yellow wire). Door is gear driven inside actuator. Feedback voltage is a function of motor position with 4.0-5.0 volts indicating full cold door position and less then one volt indicating full hot position. Operation of air mix door actuator can be evaluated using scan tool data.

On 2001 models, HVAC control module (IPM) commands the right air temperature actuator to move by controlling the voltage supplied on control circuit. A voltage of zero volts moves door toward full cold. A voltage of 2.5 volts stops door movement. A voltage of 5.0 volts moves door toward full hot. IPM determines current door position by monitoring signal circuit voltage. Feedback potentiometer is a function of motor position. A voltage of 4.0-5.0 volts indicates full hot door position. A voltage of less than one volt indicates full hot door position. IPM controls left air temperature actuator door positions in order to maintain selected air temperature.

On 2000 models, DTC will set when ignition is on and feedback circuit is open or shorted. When DTC sets, IPM will use a default value of 128 counts. This default value results in only 2 door positions: full hot and full cold. DTC can be cleared using a scan tool or interrupting IPM battery voltage. A current DTC will clear when diagnostic operates and does not fail.

On 2001 models, DTC will set when ignition is on and IPM detects signal circuit is less than 5 counts (0.09 volts) or more than 250 counts (4.90 volts). When DTC sets, IPM will use a default value in an attempt to maintain air temperature selected by driver. DTC will become history if IPM no longer detects a failure. History DTC will clear after 50 fault free ignition cycles. A current DTC can be cleared using a scan tool.

  1. Perform diagnostic system check. If diagnostic system check has not been performed, see «DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville__hvac-diagnostic-system-check) . If diagnostic system check has been performed, go to next step.
  2. Install scan tool. Start engine and bring to normal operating temperature. Using scan tool, establish communications with IPM. Recalibrate all actuators. If difference between minimum and maximum counts is within 150-220 counts, go to next step. If difference between minimum and maximum counts is not within 150-220 counts, go to step 4 .
  3. Using scan tool, clear all DTCs. Operate HVAC system. If HVAC system operates normally, go to step 18 . If HVAC system does not operate normally, go to next step.
  4. Disconnect actuator electrical connector. Measure circuit No. 705 voltage at actuator connector terminal No. 10 (Gray wire). If voltage is 5.0 volts, go to next step. If voltage is not 5.0 volts, go to step 9 .
  5. Measure circuit No. 141 voltage at actuator connector terminal No. 5 (Brown wire). If voltage is 12.0 volts, go to next step. If voltage is not 12.0 volts, go to step 9 .
  6. Measure voltage between circuit No. 141, actuator connector terminal No. 5 (Brown wire) and circuit No. 1791, actuator connector terminal No. 7 (Yellow wire). If voltage is 12.0 volts, go to next step. If voltage is not 12.0 volts, go to step 9 .
  7. Measure circuit No. 1646 voltage at actuator connector terminal No. 6 (White/Black wire). If voltage is 2.5 volts, go to next step. If voltage is not 2.5 volts, go to step 9 .
  8. Measure circuit No. 1236 voltage at actuator connector terminal No. 9 (Dark Blue wire). If voltage is 5.0 volts, go to next step. If voltage is not 5.0 volts, go to step 11 .
  9. Check suspect circuits for an open or short. If a problem is located, go to next step. If a problem is not located, go to step 11 .
  10. Repair open or short condition. When repairs are completed, go to step 21 .
  11. Using scan tool, observe ACTUATOR data. If ACTUATOR actual data displayed is 255 counts (5.0 volts), go to next step. If ACTUATOR actual data displayed is not 255 counts (5.0 volts), go to step 20 .
  12. Using a fused jumper wire, connect circuit No. 1646 at actuator connector terminal No. 9 (Dark Blue wire) to ground. If ACTUATOR actual data displayed on scan tool is zero counts (zero volts), go to next step. If ACTUATOR actual data displayed on scan tool is not zero counts (zero volts), go to step 20 .
  13. Reconnect actuator connector. If ACTUATOR actual data displayed on scan tool is 255 counts or zero counts, go to step 20 . If ACTUATOR actual data displayed on scan tool is not 255 counts or zero counts, go to next step.
  14. Using scan tool. Move actuator to hot and cold positions. If actuator moves in both directions, go to next step. If actuator does not move in both directions, go to step 16 .
  15. If actuator actual position feedback changes, go to step 21 . If actuator actual position feedback does not change, go to step 19 .
  16. Using a fused jumper wire, connect circuit No. 705 at actuator connector terminal No. 10 (Gray wire) and circuit No. 1236 at actuator connector terminal No. 6 (White/Black wire). If actuator moves, go to next step. If actuator does not move, go to step 18 .
  17. If actuator actual position feedback changes, go to step 21 . If actuator actual position feedback changes, go to step 19 .
  18. Using a fused jumper wire, connect circuit No. 1791 at actuator connector terminal No. 7 (Yellow wire) to circuit No. 1236 at actuator connect terminal No. 6 (White/Black wire). If actuator moves, go to step 17 . If actuator does not move, go to next step.
  19. Replace actuator. See «ACTUATORS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) under REMOVAL & INSTALLATION. When repairs are completed, go to step 21 .
  20. Replace IPM. See «HVAC CONTROL PANEL»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) under REMOVAL & INSTALLATION. When repairs are completed, go to next step.
  21. Using scan tool, clear all DTCs. Operate vehicle within conditions that set DTC. See «CONDITIONS FOR SETTING DTC»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . If DTC resets, go to step 2 . If DTC does not reset, system is operating properly.
  1. Perform diagnostic system check. If diagnostic system check has not been performed, see «DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville__hvac-diagnostic-system-check) . If diagnostic system check has been performed, go to next step.
  2. Install a scan tool. Turn ignition on, with engine off. Using scan tool, observe LEFT TEMP DR ACTUAL parameter in IPM HVAC DOOR POSITIONS data list. If scan tool indicates that LEFT TEMP DR ACTUAL parameter is 5-250 counts (0.09-4.90 volts), check for a disconnected or broken door. DTC sets because actuator traveled to its internal stops (overtravel condition). Check wiring harness connectors for intermittent and poor connections. Repair as necessary. See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . If indicated parameter is not 5-250 counts (0.09-4.90 volts), go to next step.
  3. Turn ignition off. Disconnect left air temperature actuator connector. Turn ignition on, with engine off. Using scan tool, observe RIGHT TEMP DR ACTUAL parameter. If scan tool indicates that RIGHT TEMP DR ACTUAL parameter is more than 250 counts (4.90 volts), go to next step. If indicated parameter is not more than 250 counts (4.90 volts), go to step 8 .
  4. Turn ignition off. Connect a 3-amp fused jumper wire between right air temperature actuator connector terminals No. 7 (Yellow wire) and No. 9 (Dark Blue wire). Turn ignition on, with engine off. Using scan tool, observe RIGHT TEMP DR ACTUAL parameter. If scan tool indicates that RIGHT TEMP DR ACTUAL parameter is less than 5 counts (0.09 volts), go to next step. If indicated parameter is not 5 counts (0.09 volts), go to step 9 .
  5. Turn ignition off. Disconnect fused jumper wire. Connect a 3-amp fused jumper wire between right air temperature actuator connector terminals No. 9 (Dark Blue wire) and No. 10 (Gray wire). Turn ignition on, with engine off. Using scan tool, observe RIGHT TEMP DR ACTUAL parameter. If scan tool indicates that RIGHT TEMP DR ACTUAL parameter is more than 250 counts (4.90 volts), go to step 7 . If indicated parameter is not 250 counts (4.90 volts), go to next step.
  6. Check for a short to ground in Gray wire between right air temperature actuator connector terminal No. 10 and IPM connector C2 terminal A1. Repair as necessary. See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . If Gray wire is okay, go to step 12 . When repairs are completed, go to step 15 .
  7. Check for a short to voltage, high resistance or an open in Gray wire between right air temperature actuator connector terminal No. 10 and IPM connector C2 terminal A1. Repair as necessary. See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . If Gray wire is okay, go to step 11 . When repairs are completed, go to step 15 .
  8. Check for a short to ground in Dark Blue wire between right air temperature actuator connector terminal No. 9 and IPM connector C2 terminal A6. Repair as necessary. See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . If Dark Blue wire is okay, go to step 12 . When repairs are completed, go to step 15 .
  9. Check for a short to voltage, high resistance, or an open in Dark Blue wire between right air temperature actuator connector terminal No. 9 and IPM connector C2 terminal A6. Repair as necessary. See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . If Dark Blue wire is okay, go to next step. When repairs are completed, go to step 15 .
  10. Check for a high resistance or an open in Yellow wire between right air temperature actuator connector terminal No. 7 and IPM connector C2 terminal A7. Repair as necessary. See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . If Yellow wire is okay, go to step 12 . When repairs are completed, go to step 15 .
  11. Check right air temperature actuator harness connector for loose or damaged terminals. Repair as necessary. See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . If connector terminals are clean and tight, go to step 13 . When repairs are completed, go to step 15 .
  12. Check IPM harness connector for loose or damaged terminals. Repair as necessary. See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . If connector terminals are clean and tight, go to step 14 . When repairs are completed, go to step 15 .
  13. Replace right air temperature actuator. See «ACTUATORS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) under REMOVAL & INSTALLATION. When repairs are completed, go to step 15 .
  14. Replace IPM. See «HVAC CONTROL PANEL»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) under REMOVAL & INSTALLATION. When repairs are completed, go to next step.
  15. Using scan tool, clear all DTCs. Operate vehicle within conditions that set DTC. See «CONDITIONS FOR SETTING DTC»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . If DTC resets, go to step 2 . If DTC does not reset, system is operating properly.

On 2000 models, rear fuse junction block supplies ignition voltage through circuit No. 141 (Brown wire). IPM commands actuator to move by suppling voltage on command line circuit No. 1614 (Dark Green wire). A zero volts signal moves door toward full cold. A 2.5 volts signal stops door movement. A 5.0 volt signal moves door toward full hot. IPM determines current door position by monitoring feedback voltage on circuit No. 1838 (Purple wire). A feedback potentiometer supplies a regulated 5.0 volt signal on circuit No. 705 (Gray wire), and a ground from IPM circuit No. 1791 (Yellow wire). Door is gear driven inside actuator. Feedback voltage is a function of motor position with 4.0-5.0 volts indicating full cold door position and less then one volt indicating full hot position. Operation of air mix door actuator can be evaluated using scan tool data.

On 2001 models, HVAC control module (IPM) commands left air temperature actuator to move by controlling voltage supplied on control circuit. A voltage of zero volts moves door toward full cold. A voltage of 2.5 volts stops door movement. A voltage of 5.0 volts moves door toward full hot. IPM determines current door position by monitoring signal circuit voltage. Feedback potentiometer is a function of motor position. A voltage of 4.0-5.0 volts indicates full hot door position. A voltage of less than one volt indicates full hot door position. IPM controls left air temperature actuator door positions in order to maintain selected air temperature.

On 2000 models, DTC will set when ignition is on and feedback circuit is open or shorted. When DTC sets, IPM will use a default value of 128 counts. This default value results in only 2 door positions: full outside air and full recirculation air. DTC can be cleared using a scan tool or interrupting IPM battery voltage. A current DTC will clear when diagnostic operates and does not fail.

On 2001 models, DTC will set when ignition is on and IPM detects a signal circuit that is less than 5 counts (0.09 volts) or more than 250 counts (4.90 volts). When DTC sets, IPM will use a default value for sensor data in an attempt to maintain air temperature selected by driver. DTC will become history if IPM no longer detects a failure. History DTC will clear after 50 fault free ignition cycles. DTC can be cleared using a scan tool.

  1. Perform diagnostic system check. If diagnostic system check has not been performed, see «DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville__hvac-diagnostic-system-check) . If diagnostic system check has been performed, go to next step.
  2. Install scan tool. Start engine and bring to normal operating temperature. Using scan tool, establish communications with IPM. Recalibrate all actuators. If difference between minimum and maximum counts is within 150-220 counts, go to next step. If difference between minimum and maximum counts is not within 150-220 counts, go to step 4 .
  3. Using scan tool, clear all DTCs. Operate HVAC system. If HVAC system operates normally, go to step 18 . If HVAC system does not operate normally, go to next step.
  4. Disconnect actuator electrical connector. Measure circuit No. 705 voltage at actuator connector terminal No. 10 (Gray wire). If voltage is 5.0 volts, go to next step. If voltage is not 5.0 volts, go to step 9 .
  5. Measure circuit No. 141 voltage at actuator connector terminal No. 5 (Brown wire). If voltage is 12.0 volts, go to next step. If voltage is not 12.0 volts, go to step 9 .
  6. Measure voltage between circuit No. 141, actuator connector terminal No. 5 (Brown wire) and circuit No. 1791, actuator connector terminal No. 7 (Yellow wire). If voltage is 12.0 volts, go to next step. If voltage is not 12.0 volts, go to step 9 .
  7. Measure circuit No. 1614 voltage at actuator connector terminal No. 6 (Dark Green wire). If voltage is 2.5 volts, go to next step. If voltage is not 2.5 volts, go to step 9 .
  8. Measure circuit No. 1838 voltage at actuator connector terminal No. 9 (Purple wire). If voltage is 5.0 volts, go to next step. If voltage is not 5.0 volts, go to step 11 .
  9. Check suspect circuits for an open or short. If a problem is located, go to next step. If a problem is not located, go to step 11 .
  10. Repair open or short condition. When repairs are completed, go to step 21 .
  11. Using scan tool, observe ACTUATOR data. If ACTUATOR actual data displayed is 255 counts (5.0 volts), go to next step. If ACTUATOR actual data displayed is not 255 counts (5.0 volts), go to step 20 .
  12. Using a fused jumper wire, connect circuit No. 1838 at actuator connector terminal No. 9 (Purple wire) to ground. If ACTUATOR actual data displayed on scan tool is zero counts (zero volts), go to next step. If ACTUATOR actual data displayed on scan tool is not zero counts (zero volts), go to step 20 .
  13. Reconnect actuator connector. If ACTUATOR actual data displayed on scan tool is 255 counts or zero counts, go to step 20 . If ACTUATOR actual data displayed on scan tool is not 255 counts or zero counts, go to next step.
  14. Using scan tool. Move actuator to full outside and full recirculation positions. If actuator moves in both directions, go to next step. If actuator does not move in both directions, go to step 16 .
  15. If actuator actual position feedback changes, go to step 21 . If actuator actual position feedback does not change, go to step 19 .
  16. Using a fused jumper wire, connect circuit No. 705 at actuator connector terminal No. 10 (Gray wire) and circuit No. 1614 at actuator connector terminal No. 6 (Dark Green wire). If actuator moves, go to next step. If actuator does not move, go to step 18 .
  17. If actuator actual position feedback changes, go to step 21 . If actuator actual position feedback changes, go to step 19 .
  18. Using a fused jumper wire, connect circuit No. 1791 at actuator connector terminal No. 7 (Yellow wire) to circuit No. 1614 at actuator connect terminal No. 6 (Dark Green wire). If actuator moves, go to step 17 . If actuator does not move, go to next step.
  19. Replace actuator. See «ACTUATORS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) under REMOVAL & INSTALLATION. When repairs are completed, go to step 21 .
  20. Replace IPM. See «HVAC CONTROL PANEL»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) under REMOVAL & INSTALLATION. When repairs are completed, go to next step.
  21. Using scan tool, clear all DTCs. Operate vehicle within conditions that set DTC. See «CONDITIONS FOR SETTING DTC»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . If DTC resets, go to step 2 . If DTC does not reset, system is operating properly.
  1. Perform diagnostic system check. If diagnostic system check has not been performed, see «DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville__hvac-diagnostic-system-check) . If diagnostic system check has been performed, go to next step.
  2. Install a scan tool. Turn ignition on, with engine off. Using scan tool, observe AIR INLET DR ACTUAL parameter in IPM HVAC DOOR POSITIONS data list. If scan tool indicates that AIR INLET DR ACTUAL parameter is 5-250 counts (0.09-4.90 volts), check for a disconnected or broken door. DTC sets because actuator traveled to its internal stops (overtravel condition). Check wiring harness connectors for intermittent and poor connections. Repair as necessary. See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . If indicated parameter is not 5-250 counts (0.09-4.90 volts), go to next step.
  3. Turn ignition off. Disconnect recirculation air temperature actuator connector. Turn ignition on, with engine off. Using scan tool, observe AIR INLET DR ACTUAL parameter. If scan tool indicates that AIR INLET DR ACTUAL parameter is more than 250 counts (4.90 volts), go to next step. If indicated parameter is not more than 250 counts (4.90 volts), go to step 8 .
  4. Turn ignition off. Connect a 3-amp fused jumper wire between right air temperature actuator connector terminals No. 7 (Yellow wire) and No. 9 (Dark Blue wire). Turn ignition on, with engine off. Using scan tool, observe AIR INLET DR ACTUAL parameter. If scan tool indicates that AIR INLET DR ACTUAL parameter is less than 5 counts (0.09 volts), go to next step. If indicated parameter is not 5 counts (0.09 volts), go to step 9 .
  5. Turn ignition off. Disconnect fused jumper wire. Connect a 3-amp fused jumper wire between recirculation actuator connector terminals No. 9 (Purple wire) and No. 10 (Gray wire). Turn ignition on, with engine off. Using scan tool, observe AIR INLET DR ACTUAL parameter. If scan tool indicates that AIR INLET DR ACTUAL parameter is more than 250 counts (4.90 volts), go to step 7 . If indicated parameter is not 250 counts (4.90 volts), go to next step.
  6. Check for a short to ground in Gray wire between right air temperature actuator connector terminal No. 10 and IPM connector C2 terminal A1. Repair as necessary. See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . If Gray wire is okay, go to step 12 . When repairs are completed, go to step 15 .
  7. Check for a short to voltage, high resistance or an open in Gray wire between recirculation actuator connector terminal No. 10 and IPM connector C2 terminal A1. Repair as necessary. See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . If Gray wire is okay, go to step 11 . When repairs are completed, go to step 15 .
  8. Check for a short to ground in Purple wire between recirculation actuator connector terminal No. 9 and IPM connector C2 terminal A4. Repair as necessary. See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . If Purple wire is okay, go to step 12 . When repairs are completed, go to step 15 .
  9. Check for a short to voltage, high resistance, or an open in Purple wire between recirculation actuator connector terminal No. 9 and IPM connector C2 terminal A4. Repair as necessary. See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . If Purple wire is okay, go to next step. When repairs are completed, go to step 15 .
  10. Check for a high resistance or an open in Yellow wire between recirculation actuator connector terminal No. 7 and IPM connector C2 terminal A7. Repair as necessary. See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . If Yellow wire is okay, go to step 12 . When repairs are completed, go to step 15 .
  11. Check recirculation actuator harness connector for loose or damaged terminals. Repair as necessary. See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . If connector terminals are clean and tight, go to step 13 . When repairs are completed, go to step 15 .
  12. Check IPM harness connector for loose or damaged terminals. Repair as necessary. See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . If connector terminals are clean and tight, go to step 14 . When repairs are completed, go to step 15 .
  13. Replace recirculation actuator. See «ACTUATORS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) under REMOVAL & INSTALLATION. When repairs are completed, go to step 15 .
  14. Replace IPM. See «HVAC CONTROL PANEL»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) under REMOVAL & INSTALLATION. When repairs are completed, go to next step.
  15. Using scan tool, clear all DTCs. Operate vehicle within conditions that set DTC. See «CONDITIONS FOR SETTING DTC»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . If DTC resets, go to step 2 . If DTC does not reset, system is operating properly.

On 2000 models, rear fuse junction block supplies ignition voltage through circuit No. 141 (Brown wire). IPM commands actuator to move by suppling voltage on command line circuit No. 1318 (Yellow wire). A zero volts signal moves door toward defrost position. A 2.5 volts signal stops door movement. A 5.0 volt signal moves door toward A/C position. IPM determines current door position by monitoring feedback voltage on circuit No. 1814 (Yellow/Black wire). A feedback potentiometer supplies a regulated 5.0 volt signal on circuit No. 705 (Gray wire), and a ground from IPM circuit No. 1791 (Yellow wire). Door is gear driven inside actuator. Feedback voltage is a function of motor position with 4.0-5.0 volts indicating A/C door position and less then one volt indicating defrost position. Operation of mode door actuator can be evaluated using scan tool data.

On 2001 models, HVAC control module (IPM) commands left air temperature actuator to move by controlling voltage supplied on control circuit. A voltage of zero volts moves door toward defrost position. A voltage of 2.5 volts stops door movement. A voltage of 5.0 volts moves door toward A/C position. IPM determines current door position by monitoring signal circuit voltage. Feedback potentiometer is a function of motor position. A voltage of 4.0-5.0 volts indicates A/C position. A voltage of less than one volt indicates defrost position. IPM controls mode actuator door positions in order to maintain selected air temperature.

On 2000 models, DTC will set when ignition is on and feedback circuit is open or shorted. When DTC sets, IPM will use a default value of 128 counts. This default value results in only 2 door positions: A/C and defrost. DTC can be cleared using a scan tool or interrupting IPM battery voltage. A current DTC will clear when diagnostic operates and does not fail.

On 2001 models, DTC will set when ignition is on and IPM detects signal circuit is less than 5 counts (0.09 volts) or more than 250 counts (4.90 volts). When DTC sets, IPM will use a default value in an attempt to move the mode actuator. DTC will become history if IPM no longer detects a failure. History DTC will clear after 50 fault free ignition cycles. A current DTC can be cleared using a scan tool.

  1. Perform diagnostic system check. If diagnostic system check has not been performed, see «DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville__hvac-diagnostic-system-check) . If diagnostic system check has been performed, go to next step.
  2. Install scan tool. Start engine and bring to normal operating temperature. Using scan tool, establish communications with IPM. Recalibrate all actuators. If difference between minimum and maximum counts is within 150-220 counts, go to next step. If difference between minimum and maximum counts is not within 150-220 counts, go to step 4 .
  3. Using scan tool, clear all DTCs. Operate HVAC system. If HVAC system operates normally, go to step 18 . If HVAC system does not operate normally, go to next step.
  4. Disconnect actuator electrical connector. Measure circuit No. 705 voltage at actuator connector terminal No. 10 (Gray wire). If voltage is 5.0 volts, go to next step. If voltage is not 5.0 volts, go to step 9 .
  5. Measure circuit No. 141 voltage at actuator connector terminal No. 5 (Brown wire). If voltage is 12.0 volts, go to next step. If voltage is not 12.0 volts, go to step 9 .
  6. Measure voltage between circuit No. 141, actuator connector terminal No. 5 (Brown wire) and circuit No. 1791, actuator connector terminal No. 7 (Yellow wire). If voltage is 12.0 volts, go to next step. If voltage is not 12.0 volts, go to step 9 .
  7. Measure circuit No. 1318 voltage at actuator connector terminal No. 6 (Yellow wire). If voltage is 2.5 volts, go to next step. If voltage is not 2.5 volts, go to step 9 .
  8. Measure circuit No. 1814 voltage at actuator connector terminal No. 9 (Yellow/Black wire). If voltage is 5.0 volts, go to next step. If voltage is not 5.0 volts, go to step 11 .
  9. Check suspect circuits for an open or short. If a problem is located, go to next step. If a problem is not located, go to step 11 .
  10. Repair open or short condition. When repairs are completed, go to step 21 .
  11. Using scan tool, observe ACTUATOR data. If ACTUATOR actual data displayed is 255 counts (5.0 volts), go to next step. If ACTUATOR actual data displayed is not 255 counts (5.0 volts), go to step 20 .
  12. Using a fused jumper wire, connect circuit No. 1814 at actuator connector terminal No. 9 (Yellow/Black wire) to ground. If ACTUATOR actual data displayed on scan tool is zero counts (zero volts), go to next step. If ACTUATOR actual data displayed on scan tool is not zero counts (zero volts), go to step 20 .
  13. Reconnect actuator connector. If ACTUATOR actual data displayed on scan tool is 255 counts or zero counts, go to step 20 . If ACTUATOR actual data displayed on scan tool is not 255 counts or zero counts, go to next step.
  14. Using scan tool. Move actuator to defrost and A/C positions. If actuator moves in both directions, go to next step. If actuator does not move in both directions, go to step 16 .
  15. If actuator actual position feedback changes, go to step 21 . If actuator actual position feedback does not change, go to step 19 .
  16. Using a fused jumper wire, connect circuit No. 705 at actuator connector terminal No. 10 (Gray wire) and circuit No. 1318 at actuator connector terminal No. 6 (Yellow wire). If actuator moves, go to next step. If actuator does not move, go to step 18 .
  17. If actuator actual position feedback changes, go to step 21 . If actuator actual position feedback does not change, go to step 19 .
  18. Using a fused jumper wire, connect circuit No. 1791 at actuator connector terminal No. 7 (Yellow wire) to circuit No. 1318 at actuator connect terminal No. 6 (Yellow wire). If actuator moves, go to step 17 . If actuator does not move, go to next step.
  19. Replace actuator. See «ACTUATORS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) under REMOVAL & INSTALLATION. When repairs are completed, go to step 21 .
  20. Replace IPM. See «HVAC CONTROL PANEL»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) under REMOVAL & INSTALLATION. When repairs are completed, go to next step.
  21. Using scan tool, clear all DTCs. Operate vehicle within conditions that set DTC. See «CONDITIONS FOR SETTING DTC»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . If DTC resets, go to step 2 . If DTC does not reset, system is operating properly.
  1. Perform diagnostic system check. If diagnostic system check has not been performed, see «DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville__hvac-diagnostic-system-check) . If diagnostic system check has been performed, go to next step.
  2. Install a scan tool. Turn ignition on, with engine off. Using scan tool, observe MODE DOOR ACTUAL parameter in IPM HVAC DOOR POSITIONS data list. If scan tool indicates that MODE DOOR ACTUAL parameter is 5-250 counts (0.09-4.90 volts), check for a disconnected or broken door. DTC sets because actuator traveled to its internal stops (overtravel condition). Check wiring harness connectors for intermittent and poor connections. Repair as necessary. See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . If indicated parameter is not 5-250 counts (0.09-4.90 volts), go to next step.
  3. Turn ignition off. Disconnect mode door actuator connector. Turn ignition on, with engine off. Using scan tool, observe MODE DOOR ACTUAL parameter. If scan tool indicates that MODE DOOR ACTUAL parameter is more than 250 counts (4.90 volts), go to next step. If indicated parameter is not more than 250 counts (4.90 volts), go to step 8 .
  4. Turn ignition off. Connect a 3-amp fused jumper wire between mode door actuator connector terminals No. 7 (Yellow wire) and No. 9 (Yellow/Black wire). Turn ignition on, with engine off. Using scan tool, observe MODE DOOR ACTUAL parameter. If scan tool indicates that MODE DOOR ACTUAL parameter is less than 5 counts (0.09 volts), go to next step. If indicated parameter is not 5 counts (0.09 volts), go to step 9 .
  5. Turn ignition off. Disconnect fused jumper wire. Connect a 3-amp fused jumper wire between mode door actuator connector terminals No. 9 (Yellow/Black wire) and No. 10 (Gray wire). Turn ignition on, with engine off. Using scan tool, observe MODE DOOR ACTUAL parameter. If scan tool indicates that MODE DOOR ACTUAL parameter is more than 250 counts (4.90 volts), go to step 7 . If indicated parameter is not 250 counts (4.90 volts), go to next step.
  6. Check for a short to ground in Gray wire between mode door actuator connector terminal No. 10 and IPM connector C2 terminal A1. Repair as necessary. See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . If Gray wire is okay, go to step 12 . When repairs are completed, go to step 15 .
  7. Check for a short to voltage, high resistance or an open in Gray wire between mode door actuator connector terminal No. 10 and IPM connector C2 terminal A1. Repair as necessary. See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . If Gray wire is okay, go to step 11 . When repairs are completed, go to step 15 .
  8. Check for a short to ground in Yellow/Black wire between mode door actuator connector terminal No. 9 and IPM connector C2 terminal A2. Repair as necessary. See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . If Yellow/Black wire is okay, go to step 12 . When repairs are completed, go to step 15 .
  9. Check for a short to voltage, high resistance, or an open in Yellow/Black wire between mode door actuator connector terminal No. 9 and IPM connector C2 terminal A2. Repair as necessary. See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . If Yellow/Black wire is okay, go to next step. When repairs are completed, go to step 15 .
  10. Check for a high resistance or an open in Yellow wire between mode door actuator connector terminal No. 7 and IPM connector C2 terminal A7. Repair as necessary. See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . If Yellow wire is okay, go to step 12 . When repairs are completed, go to step 15 .
  11. Check mode door actuator harness connector for loose or damaged terminals. Repair as necessary. See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . If connector terminals are clean and tight, go to step 13 . When repairs are completed, go to step 15 .
  12. Check IPM harness connector for loose or damaged terminals. Repair as necessary. See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . If connector terminals are clean and tight, go to step 14 . When repairs are completed, go to step 15 .
  13. Replace mode door actuator. See «ACTUATORS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) under REMOVAL & INSTALLATION. When repairs are completed, go to step 15 .
  14. Replace IPM. See «HVAC CONTROL PANEL»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) under REMOVAL & INSTALLATION. When repairs are completed, go to next step.
  15. Using scan tool, clear all DTCs. Operate vehicle within conditions that set DTC. See «CONDITIONS FOR SETTING DTC»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . If DTC resets, go to step 2 . If DTC does not reset, system is operating properly.

On 2000 models, Keyboard Data Display (KDD) is data bus used to communicate between IPM and HVAC control panel. HVAC control panel is part IPM and is serviced as one component. This DTC is an internal IPM error.

On 2001 models, internal fault detection is handled inside HVAC control module (IPM). No external circuits are involved.

On 2000 models, DTC will set when ignition is on and an internal open or short is detected. When DTC sets, IPM will use a default value of 70°F (21°C) to allow operation of HVAC system. DTC will change from current to history during an ignition cycle if IPM no longer detects an internal error. A history DTC will clear after 50 consecutive ignition cycles if condition for malfunction is no longer present. DTC can be cleared using a scan tool or interrupting IPM battery voltage.

On 2001 models, a microprocessor runs program to detect an internal fault when power-up is commanded, only requiring voltage and ground. This program runs even if voltage is out of valid operating range. Microprocessor first writes information to a cell, or address. It adds 0.25 to value and calculates a check sum. If this check sum, minus 0.25, is not equal to cell value, module will set DTC. When DTC sets, microprocessor will refuse all additional inputs. DTC clears when microprocessor makes a successful write to EEPROM and check sum procedure.

  1. Perform diagnostic system check. If diagnostic system check has not been performed, see «DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville__hvac-diagnostic-system-check) . If diagnostic system check has been performed, go to next step.
  2. Turn ignition on. Using scan tool, clear any DTCs. Turn ignition off. Turn ignition on. If DTC resets, go to next step. If DTC does not reset, HVAC system is operating properly.
  3. Replace IPM. See «HVAC CONTROL PANEL»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) under REMOVAL & INSTALLATION. When repairs are completed, go to next step.
  4. Turn ignition off. Reconnect or install any connectors or components that were disconnected or removed. Turn ignition on. Using scan tool, clear all DTCs. If all DTCs cleared, HVAC system is operating properly. If all DTCs did not clear, go to «DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville__hvac-diagnostic-system-check) .

Note. This DTC may be stored as a history DTC without affecting module operation. If DTC is stored only as a history DTC and not retrieved as a current DTC, do not replace module. If this DTC is retrieved as both a current and history DTC, replace module.

  1. Perform diagnostic system check. If diagnostic system check has not been performed, see «DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville__hvac-diagnostic-system-check) . If diagnostic system check has been performed, go to next step.
  2. Install a scan tool. Turn ignition on, with engine off. Using scan tool, observe current DTC parameter in IPM DIAGNOSTIC TROUBLE CODES list. Retrieve all DTCs. If DTC is current, go to next step. If DTC is not current, check wiring harness connectors for intermittent and poor connections. Repair as necessary. See «WIRING DIAGRAMS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) .
  3. Replace IPM. See «HVAC CONTROL PANEL»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) under REMOVAL & INSTALLATION. When repairs are completed, go to next step.
  4. Using scan tool, clear all DTCs. Operate vehicle within conditions that set DTC. See «CONDITIONS FOR SETTING DTC»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) . If DTC resets, go to step 2 . If DTC does not reset, system is operating properly.

Circuit Description (2001 Models)

On 2001 models, steering wheel controls are simple momentary contact switches that connect a series of resistors so that each switch selection corresponds to a fixed resistance value. Dash Integration Module (DIM) determines which switch has been pressed by voltage drop across corresponding resistance value.

Conditions For Setting DTC (2001 Models)

On 2001 models, DTC will set when DIM is powered and one left steering wheel control switch is active (pressed) for at least 30 seconds. When DTC sets, DIM will disable only temperature and blower switches while fault is present. DTC will become history if DIM no longer detects a failure. History DTC will clear after 50 fault free ignition cycles. DTC can be cleared with a scan tool.

  1. Perform diagnostic system check. If diagnostic system check has not been performed, see «DIAGNOSTIC SYSTEM CHECK»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville__hvac-diagnostic-system-check) . If diagnostic system check has been performed, go to next step.
  2. Install a scan tool. Turn ignition on, with engine off. Using scan tool, observe STEERING WHEEL CONTROLS parameter in DIM data inputs. If scan tool indicates STEERING WHEEL CONTROLS parameter is not 0-7 Counts, go to next step. If scan tool indicates STEERING WHEEL CONTROLS parameter is 0-7 Counts, check counts for left steering wheel control switches. See «LEFT STEERING WHEEL SWITCH COUNTS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) table. If switch counts are not as specified, check steering wheel wiring harness. Repair as necessary. When repairs are completed, go to step 4 .
  3. Replace steering wheel control switches. See «STEERING WHEEL CONTROL SWITCHES»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) under REMOVAL & INSTALLATION. When repairs are completed, go to next step.
  4. Using scan tool, clear all DTCs. Operate vehicle within conditions that set DTC. See «CONDITIONS FOR SETTING DTC»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville__conditions-for-setting-dtc-2001-models) . If DTC resets, go to step 2 . If DTC does not reset, system is operating properly.
Switch Position(1) Switch Counts
No InputZero
TEMP DOWN18
TEMP UP36
FAN DOWN55
FAN UP73
(1) Using scan tool, observe STEERING WHEEL CONTROLS parameter in Dash Integration Module (DIM) data inputs.
(1)Using scan tool, observe STEERING WHEEL CONTROLS parameter in Dash Integration Module (DIM) data inputs.

LEFT STEERING WHEEL SWITCH COUNTS

A/C SYSTEM PERFORMANCE

  1. Park vehicle in shaded area. Ventilate interior. Vent exhaust. Install manifold gauge set. Measure and record ambient temperature and relative humidity. Close doors and windows. Set controls to AUTO, select maximum blower speed, and set temperature control to coldest value. Insert thermometer into center outlet.
  2. Set transmission in Park or Neutral. Start and idle engine for 10 minutes. Record outlet temperature, and high-side and low-side pressures. Turn ignition switch to OFF position (engine off). Compare readings with specifications. See «A/C PERFORMANCE SPECIFICATIONS»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville) table.
Ambient Temp. - °F (°C)Outlet Temp. - °F (°C)Low-Side Pressure - psi (kg/cm 2 )High-Side Pressure - psi (kg/cm 2 )
70 (21)49-58 (9-14)25-45 (1.8-3.2)155-225 (10.9-15.8)
80 (27)52-66 (11-19)35-55 (2.5-3.9)230-295 (16.1-20.7)
90 (32)57-75 (14-24)42-65 (3.0-4.6)270-340 (19.0-23.9)
100 (38)65-86 (18-30)52-85 (3.7-6.0)310-420 (21.8-29.5)

A/C PERFORMANCE SPECIFICATIONS

Inside Temperature Sensor

Turn ignition off. Disconnect inside air temperature sensor 4-pin connector. Measure resistance between sensor terminals "A" (Dark Green wire) and "D" (Yellow wire) at various temperatures. See INSIDE TEMPERATURE SENSOR RESISTANCE table. If resistance is not as specified, replace temperature sensor.

Temperature - °F (°C)(K/Ohms)
14 (-10)15.42-17.23
23 (-5)11.35-13.08
32 (0)8.72-10.01
41 (5)6.75-7.72
50 (10)5.27-6.00
59 (15)4.14-4.70
58 (20)3.28-3.71
77 (25)2.62-2.95
86 (30)2.10-2.36
95 (35)1.70-1.90
104 (40)1.38-1.54

INSIDE TEMPERATURE SENSOR RESISTANCE

Turn ignition off. Disconnect outside air temperature sensor 2-pin connector. Measure resistance between sensor terminals at various temperatures. See OUTSIDE (AMBIENT) TEMPERATURE SENSOR RESISTANCE table. If resistance is not as specified, replace temperature sensor.

Temperature - °F (°C)(K/Ohms)
14 (-10)5.27-5.98
23 (-5)4.03-4.52
32 (0)3.11-3.44
41 (5)2.43-2.66
50 (10)1.91-2.07
59 (15)1.51-1.62
58 (20)1.21-1.28
77 (25)0.97-1.02
86 (30)0.78-0.82
95 (35)0.63-0.67
104 (40)0.51-0.55

OUTSIDE (AMBIENT) TEMPERATURE SENSOR RESISTANCE

REMOVAL & INSTALLATION

WARNINGTo avoid injury from accidental air bag deployment, read and carefully follow all SERVICE PRECAUTIONS and DISABLING & ACTIVATING AIR BAG SYSTEM procedures in AIR BAG SYSTEM SAFETY article in GENERAL SERVICING.
  1. Discharge HVAC system, using approved refrigerant recovery/recycling equipment. Remove right wheelwell. Remove accessory drive belt. Disconnect evaporator hose from condenser. Disconnect suction and discharge hoses. Remove electrical connector from compressor. Remove generator and compressor mounting bolts. Remove compressor through wheelwell opening.
  2. Drain and measure old oil from compressor. If less than one ounce of oil is drained from compressor, replace with 2 ounces of refrigerant oil. If more than one ounce of old oil is drained from compressor, replace with same amount of refrigerant oil. To install, reverse removal procedure. Install NEW "O" rings. Evacuate, charge, and leak test HVAC system.
  1. Discharge HVAC system, using approved refrigerant recovery/recycling equipment. Remove suction hose retainer and suction hose from accumulator. Remove evaporator hose from accumulator. Plug all lines and openings. Disconnect accumulator retainer and remove accumulator from vehicle.
  2. Drain and measure old oil from accumulator. Add same amount of oil drained plus one ounce, of NEW refrigerant oil (maximum of 3 ounces) to replacement accumulator. To install, reverse removal procedure. Install NEW "O" rings. Evacuate, charge, and leak test HVAC system.

Removal & Installation (Driver's Air Mix)

Remove left side hush panel from under Instrument Panel (IP). Remove drivers air mix actuator screws. Disconnect electrical connector. Remove actuator from vehicle. (Scheme 3) To install, reverse removal procedure.

Removal & Installation (Passenger's Air Mix)

Remove right side hush panel from under IP. Remove passenger's air mix actuator screws. Disconnect electrical connector. Remove actuator from vehicle. To install, reverse removal procedure.

Removal & Installation (Air Inlet)

Remove right side hush panel from under IP. Remove Dash Integration Module (DIM) bracket. Remove blower control module retaining screws and move module off to side. Remove air inlet actuator screws. Disconnect electrical connector. Remove actuator from vehicle. To install, reverse removal procedure.

Removal & Installation (Mode)

Remove IP carrier. See INSTRUMENT PANEL. Remove driver's air mix door actuator. Remove mode actuator screws. Disconnect electrical connector. Remove actuator from vehicle. (Scheme 3) To install, reverse removal procedure.

Mode (Auxiliary)

Remove left side center console panel. Remove auxiliary mode actuator screws. Disconnect electrical connector. Remove actuator from vehicle. (Scheme 4) To install, reverse removal procedure.

  1. Remove left and right center console panels. Remove console trim panel by lifting upward on rear edge of panel to disengage retaining clips, and pull rearward. Remove center console storage bin(s) by pulling upward. Lift upward on cover on floor of center console to access rear nuts and remove nuts. Remove bolts from middle side of console. Bend metal bracket arms in to clear console.
  2. Disconnect shift cable and remove bolt attaching cable to bracket. Disconnect Brake Transmission Shift Interlock (BTSI) solenoid rod from shifter. (Scheme 6) Disconnect all electrical connectors from center console assembly. Remove bolts attaching center console to lower Instrument Panel (IP). Lift up on rear of center console and slide rearward to clear lower IP. Remove center console from vehicle.
  3. Remove console bracket. Disconnect mode actuator and blower motor electrical connectors. Remove rear air duct. Slide entire assembly toward rear of vehicle and remove. (Scheme 4) To install, reverse removal procedure.

Scheme 6

Scheme 6
Scheme 6

Removal & Installation (Main HVAC Module)

Remove right side hush panel from under Instrument Panel (IP). Disconnect blower motor electrical connector. Remove blower motor retaining screws. Grasp blower motor and rotate clockwise to disengage from HVAC module. (Scheme 7) To install, reverse removal procedure.

Scheme 7

Scheme 7: Removal & Installation (Main HVAC Module)
Scheme 7: Removal & Installation (Main HVAC Module)

Remove Dash Integration Module. See DASH INTEGRATION MODULE (DIM) . Remove DIM bracket screws and remove bracket from HVAC module. Disconnect blower control module electrical connector. Remove screw and remove blower control module from HVAC module. To install, reverse removal procedure.

Remove Instrument Panel (IP) trim panel above radio assembly by carefully prying out with a small, hooked tool. Remove console trim panel by lifting upward on rear edge of panel to disengage retaining clips and pull rearward. Disconnect electrical connectors. Remove control panel/radio bracket screws. Disconnect electrical connectors from control panel and radio. Remove control panel-to-bracket nuts. Remove control panel from bracket. (Scheme 8) To install, reverse removal procedure.

Scheme 8

Scheme 8: Removal & Installation
Scheme 8: Removal & Installation
  1. Discharge HVAC system, using approved refrigerant recovery/recycling equipment. Remove upper plastic filler panel above condenser. Remove right headlight and hood latch bracket to access condenser mounting and hoses. Remove discharge and evaporator hoses from condenser.
  2. Remove mounting bolts. Remove condenser from left retainer first, then remove from right retainer. To install, reverse removal procedure making sure to install right side of condenser to retainers first. Install NEW "O" rings. Evacuate, charge, and leak test HVAC system.

Remove right side hush panel. Disconnect DIM electrical connector. Slide DIM upward to disengage from bracket. Remove from vehicle. To install, reverse removal procedure.

Remove HVAC module assembly. See HVAC MODULE ASSEMBLY . Remove seal from around heater core and evaporator case and discard. Remove upper evaporator case and remove evaporator core. Remove and discard all seals. To install, reverse removal procedure, using all NEW seals.

Remove HVAC module assembly. See HVAC MODULE ASSEMBLY . Remove seal from around heater core and evaporator case and discard. Remove heater core cover screws and remove cover. Remove heater core retaining straps and remove heater core. Remove and discard all seals. To install, reverse removal procedure, using all NEW seals.

  1. Remove left hush panel from under Instrument Panel (IP). Twist shift cable grommet and position away from filter access cover. (Scheme 9) Remove filter access cover located at rear of HVAC module to right of accelerator pedal. Grasp filters by tabs to remove (filters will bend slightly to clear accelerator pedal).
  2. When installing filters make sure to line up interlocking tabs. Filters install from bottom up. After installing first filter use tab to raise up and install next filter until 3 filters are installed. Make sure first 2 filters catch on holding rib inside HVAC module before installing third filter. Install access cover and reposition shift cable grommet.

Scheme 9

Scheme 9
Scheme 9
  1. Discharge HVAC system using approved refrigerant recovery/recycling equipment. Drain engine coolant. Disable air bag system. See AIR BAG SYSTEM SAFETY article in GENERAL SERVICING. Disconnect evaporator hose assembly from evaporator core. Below evaporator hose assembly, disconnect heater hoses from heater core. Raise vehicle and remove evaporator drain tube.
  2. Remove instrument panel assembly. See «INSTRUMENT PANEL»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville). Disconnect all electrical connectors from HVAC module. Remove defroster nozzle. (Scheme 3) Remove rear heater duct. (Scheme 4) Remove HVAC module retaining nuts and remove HVAC module.
  3. To install, reverse removal procedure. Install NEW "O" rings. Evacuate, charge, and leak test HVAC system.
  1. Disable air bag system. See AIR BAG SYSTEM SAFETY article in GENERAL SERVICING. Remove center console. See «AUXILIARY BLOWER/MODE ASSEMBLY»(/cadillac/seville/v-1998-2004/remont/automatic-hvac-system/#hvac-system-automatic-seville). Remove right hush panel and both Instrument Panel (IP) end caps. Remove side window defroster ducts by pulling outward. Remove left and right windshield garnish moldings by pulling down and back to disengage clips. Use flat-blade screwdriver to press on locking tabs for IP vents while pulling outward. Remove all IP vents.
  2. Remove screws inside IP vent openings, attaching IP upper trim pad. Lift pad upward slightly to disengage retainers from IP cluster trim plate. Push down on IP upper trim pad above passenger air bag module while sliding trim pad rearward to disengage retainer in front of air bag. Disconnect electrical connector. Remove IP upper trim pad.
  3. Remove screws attaching defroster grille and disconnect electrical connectors. Remove defroster grille. Remove left hush panel and attaching bolts for knee bolster. Remove knee bolster. Disconnect IP electrical connectors at top outside corners of IP.
  4. Disconnect pinch bolt at base of steering column and slide off shaft (note steering wheel and shaft location for installation). Disconnect steering column body connector and SIR (Yellow) connector. Remove nuts at base of steering column and at steering column to instrument panel. (Scheme 10) Remove steering column. Remove bolts attaching steering column support to IP carrier.
  5. Remove IP center support to floor bracket bolts. Remove IP carrier to hinge pillar support bolts and cowl fastener nuts. Remove IP carrier from vehicle. (Scheme 11) To install, reverse removal procedure.

Scheme 10

Scheme 10
Scheme 10

Scheme 11

Scheme 11
Scheme 11

Removal & Installation (A/C Refrigerant Pressure Sensor)

Raise and support vehicle. Remove front air deflector. Disconnect A/C refrigerant pressure sensor electrical connector. Remove A/C refrigerant pressure sensor. To install, reverse removal procedure. Use a NEW "O" ring lubricated with refrigerant oil.

Removal & Installation (A/C Refrigerant Low Temperature Sensor)

Discharge HVAC system using approved refrigerant recovery/recycling equipment. Disconnect A/C refrigerant low temperature sensor connector. Disconnect sensor from refrigerant line. To install, reverse removal procedure.

Removal & Installation (A/C Temperature)

Remove Instrument Panel (IP) upper trim pad. See INSTRUMENT PANEL . Disconnect sensor electrical connector. Twist A/C temperature sensor 1/4 turn and remove it from ducts. To install, reverse removal procedure.

Removal & Installation (Ambient Temperature)

Remove upper plastic filler panel above condenser. Disconnect electrical connector from sensor. Remove retainer from ambient temperature sensor. To install, reverse removal procedure.

Removal & Installation (Heater Temperature)

Remove center console side panels. Remove left and right hush panels under instrument panel. Disconnect electrical connectors from left and right heater temperature sensors and twist 1/4 turn to remove from A/C-heater outlet ducts. To install, reverse removal procedure.

Removal & Installation (In-Vehicle Temperature)

Remove left IP end cap and side window defroster duct. Push on rear of headlight switch to remove. Disconnect headlight switch electrical connector. Remove in-vehicle temperature sensor retaining screw. Disconnect electrical connector and remove sensor from vehicle. To install, reverse removal procedure.

Removal & Installation (Sun Load)

Remove IP upper trim pad. See INSTRUMENT PANEL . Remove defroster grille attachment screws. Remove defroster grille and remove sun load sensors by twisting 1/4 turn. Disconnect sensor electrical connectors and remove. To install, reverse removal procedure.

Disable air bag system. See AIR BAG SYSTEM SAFETY article in GENERAL SERVICING. Remove driver's air bag module. Carefully pull steering wheel control switch away from steering wheel to release switch from steering wheel. Disconnect electrical connectors. Remove steering wheel control switch. To install, reverse removal procedure.

TORQUE SPECIFICATIONS

ApplicationFt. Lbs. (N.m)
A/C Compressor Mounting Bolts18 (25)
Condenser Bolts/Nuts10 (13)
Evaporator Hose-To-Accumulator13 (18)
Evaporator Hose-To-Condenser13 (18)
Evaporator Hose-To-Evaporator13 (18)
High-Pressure (Discharge) Hose Nut
At Compressor16 (22)
At Condenser13 (18)
HVAC Module Mounting Nut10 (13)
Low-Pressure (Suction) Hose Nut
At Accumulator16 (22)
At Compressor16 (22)
INCH Lbs. (N.m)
Blower Motor Bolt/Nut84 (9)
Instrument Panel-To-Center Floor Bracket Bolt84 (9)
Instrument Panel-To-Steering Column Bolt84 (9)

TORQUE SPECIFICATIONS

Automatic A/C-Heater System Wiring Diagram (2000 Seville - 1 Of 2). Scheme 12

Scheme 12: Automatic A/C-Heater System Wiring Diagram (2000 Seville - 1 Of 2)
Scheme 12: Automatic A/C-Heater System Wiring Diagram (2000 Seville - 1 Of 2)

Automatic A/C-Heater System Wiring Diagram (2000 Seville - 2 Of 2). Scheme 13

Scheme 13: Automatic A/C-Heater System Wiring Diagram (2000 Seville - 2 Of 2)
Scheme 13: Automatic A/C-Heater System Wiring Diagram (2000 Seville - 2 Of 2)

Automatic A/C-Heater System Wiring Diagram (2001 Seville - 1 Of 2). Scheme 14

Scheme 14: Automatic A/C-Heater System Wiring Diagram (2001 Seville - 1 Of 2)
Scheme 14: Automatic A/C-Heater System Wiring Diagram (2001 Seville - 1 Of 2)

Automatic A/C-Heater System Wiring Diagram (2001 Seville - 2 Of 2). Scheme 15

Scheme 15: Automatic A/C-Heater System Wiring Diagram (2001 Seville - 2 Of 2)
Scheme 15: Automatic A/C-Heater System Wiring Diagram (2001 Seville - 2 Of 2)