HVAC System - Automatic Cadillac Eldorado X

A/C SYSTEM SPECIFICATIONS

A/C SYSTEM SPECIFICATIONS

DESCRIPTION

Note. A/C-Heater Programmer may also be referred as Air Conditioning Module (ACM). Body Control Module (BCM) may also be referred as Platform Zone Module (PZM).

The Electronic Climate Control (ECC) 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. The A/C-Heater Programmer (ACM) is the main control for selecting in-vehicle comfort levels. (Scheme 1)or (Scheme 2).

Main components of ECC system are A/C-Heater Programmer (ACM), Powertrain Control Module (PCM), refrigerant system, temperature sensors, and Heating, Ventilation and Air Conditioning (HVAC) module.

BLOWER FAN CONTROL

When AUTO button is selected, blower speeds are controlled automatically based on various system inputs. If up arrow is pressed once, blower speed increases slightly and control panel displays HI AUTO. 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.

Eldorado & Seville

The blower fan control, located at rear of console, is manually controlled. A slide lever with 5 positions (off, low, medium, medium high and high) is used. ACM monitors blower speed feedback for diagnosis.

TEMPERATURE SETTINGS

Temperature settings range from 60°F (16°C) to 90°F (32°C). Turning the temperature control knob in either direction or pressing the COOL or WARM button once will decrease or increase the 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 the setting reaches 65°F (18°C), the next lowest available temperature setting is 60°F (16°C), representing maximum cooling. At the 85°F (29°C) setting, the next highest available temperature setting is 90°F (32°C), representing maximum heating. The selected temperature is displayed on the climate control panel display.

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

OFF Mode

When OFF mode is selected, system does not allow fan blower motor or A/C compressor operation; however, system will attempt to maintain selected temperature by regulating air-mix valve.

Because fan and A/C compressor do not operate, set temperature will probably not be reached. When in OFF mode, Climate Control Panel (CCP) will display only outside temperature.

ECON Mode

In this mode, A/C compressor does not operate. System will adjust to selected temperature. Temperature inside vehicle cannot be cooler than outside temperature.

AUTO Mode

With this setting selected, the entire system, including compressor operation, is controlled automatically by various inputs to adjust to selected temperature.

In this mode, 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.

DEFOG Mode

In this setting, air is divided equally between floor and defroster vents. Compressor is allowed to operate at temperatures greater than 40°F (4°C) to dehumidify passenger compartment air.

Defrost Mode

In this setting, everything is controlled automatically. Most of air is delivered to windshield.

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

In this setting, operation is the same as AUTO mode, except air mix door is split and each side has its own actuator. A/C-Heater Programmer (ACM) operates each actuator separately, according to control panel and passenger temperature control settings. When system is operating in any mode except dual zone mode, actuators operate in unison.

RECIRC Mode

In this setting, inside air is recirculated through A/C-heater system. RECIRC mode is not available during DEFROST or DEFOG mode. Manual RECIRC mode is canceled when any other mode is selected or ignition is cycled off.

Scheme 1

Scheme 2

AIR DELIVERY SYSTEM

The Heating, Ventilation and Air Conditioning (HVAC) assembly incorporates most of the air conditioning components into one assembly. The function of the air delivery system is to distribute airflow throughout the vehicle. Major components of the 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) Eldorado and Seville have an auxiliary blower in the console to direct air to rear seat occupants.

Scheme 3

A/C-HEATER PROGRAMMER

The A/C-Heater Programmer (ACM) is located behind the glove box, attached to bracket next to right end of HVAC module assembly. The ACM controls temperature regulation through control of the air-mix valve motor. Air mix valve motor provides a feedback signal to indicate valve position. ACM also controls 4 vacuum solenoids which control air inlet-recirculation valve, A/C defrost valve, up-down valve and parking brake release. The ACM is equipped with a self-diagnostic function.

Diagnostic Trouble Codes (DTCs)

The PCM and ACM monitor operating conditions for possible system malfunctions. If a fault is detected, a DTC will be set in memory. See ACM SELF-DIAGNOSTICS under TESTING.

TEMPERATURE SENSOR INPUTS

The ACM monitors 5 temperature sensor inputs and one solar input.

In-Vehicle Temperature Sensor

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

Outside 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 ACM and displayed on climate control center.

Coolant Temperature Sensor

The coolant temperature sensor is located in a coolant passage of the intake manifold. Its output is monitored by the PCM, which in turn sends a signal to the ACM for system operation calculations.

A/C High-Side Temperature Sensor

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

A/C Low-Side Temperature Sensor

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

Sunload Sensor

The sunload sensor is located under the center defroster grille, at base of windshield. This sensor uses a light sensitive photocell to measure amount of sunlight hitting vehicle. Sensor voltage is lowest in direct sunlight and highest when shaded. The ACP processes this signal together with temperature signals to determine the cooling necessary for maintaining selected interior temperature.

HIGH REFRIGERANT PRESSURE SWITCH

The high refrigerant pressure switch is located in the compressor discharge line. Switch monitors compressor discharge pressure. If refrigerant pressure rises to more than 430 psi (30.2 kg/cm 2 ), switch opens the circuit to the clutch. When pressure drops to 200 psi (14.1 kg/cm 2 ), switch will close and allow compressor operation.

LOW REFRIGERANT PRESSURE SWITCH

The low refrigerant pressure switch is located in the low-pressure refrigerant line. When pressurized, the switch is closed and allows the ignition circuit to feed the compressor clutch coil through the compressor clutch relay. If refrigerant pressure drops to less than 2 psi (0.1 kg/cm 2 ), the switch opens the circuit to the clutch. The ACM monitors the switch for diagnostic purposes.

PROGRAM NUMBER

The program number is calculated by the ACM to determine the amount of heating or cooling required to meet the desired in-vehicle temperature. This number is based on set temperature, outside temperature, in-vehicle temperature, and sunload sensor.

The program number determines the proper air delivery mode and blower speed, and is also a factor in determining air-mix valve position. A program number of zero indicates maximum system cooling, and a program number of 255 represents maximum heating. Program number can be observed using scan tool.

AIR-MIX VALVE POSITION

ACM determines appropriate air-mix valve position by monitoring set temperature, outside air temperature, in-vehicle air temperature, low-side temperature, sunload sensor voltage, coolant temperature, air delivery mode, engine RPM, blower speed, and air-mix motor position feedback signal. Based on these inputs, ACM positions air mix valve for an appropriate blend of air based on current program number.

BLOWER SPEED CONTROL

For every program number and climate control panel setting, ACM has a calculated blower motor voltage. Based on a signal sent from the ACM, a variable voltage is sent to the blower motor. Blower speed for the rear console blower is controlled manually.

AIR DELIVERY MODE CONTROL

ACM will direct blended air in one of several air delivery modes, based on current program number and climate control center settings. See TEMPERATURE & MODE SETTINGS . Side window and rear air outlets receive airflow in all modes. Rear air outlets may be shut off using VENT dial on rear of console. The following air delivery modes are possible.

Note. When using scan tool, it is possible to override the following modes to observe complete operation of each mode.

MAX A/C Mode

Air flows through A/C outlets with bleed to heater outlets. When AUTO is selected, air inlet valve slowly opens to provide 90 percent recirculated air. When ECON is selected, air inlet valve remains closed to provide only outside air.

A/C Mode

Air flows through A/C outlets with bleed to heater outlets. If previously operating in AUTO-MAX A/C mode, inlet valve slowly closes to provide only outside air.

Bi-Level Mode

Air flows through A/C outlets and heater outlets. This mode is used in transition of A/C to heater mode or vice-versa.

Heater Mode

Air flows through heater outlets with bleed to defrost outlets.

In this setting, air is divided equally between floor and defroster vents. Compressor is enabled to dehumidify passenger compartment air if ambient temperature is more than 40°F (4°C). This mode can be entered manually by pressing DEFOG button on standard control panel or mode select button on optional dual zone control panel.

When OFF mode is selected, system does not allow blower motor or A/C compressor operation. Air entering vehicle is directed the same as in HEATER mode. System will attempt to maintain selected temperature by regulating air-mix valve.

Front Defrost Mode

Air flows through defroster outlets with bleed to heater outlets. If outside air temperature is less than 25°F (-4°C), ACM will limit blower to 7 volts until coolant temperature has exceeded 97°F (36°C) for 3 minutes. Selecting blower HI setting will override 7-volt limit.

IPC Cooling Mode

When necessary, blower will turn on and direct air to A/C outlets to cool Instrument Panel Cluster (IPC) in order to prevent damage to electronic components. IPC cooling is enabled under following conditions: ignition switch is in RUN position, engine is not running or HVAC is off, in-vehicle temperature is more than 125°F (51°C), or blower override modes are not operating. When enabled, minimum run time is 4 minutes. IPC cooling mode is disabled if in-vehicle temperature is less than 121°F (50°C), or engine is running and HVAC is not off, engine is running, diagnostics is entered or if a PCM-IPC serial data fault is present.

Purge Modes

One of 3 purge modes (normal, cold or A/C purge) occur when system is first turned on, if certain conditions exist. Purge modes are intended to improve comfort and reduce windshield fogging. Airflow is redirected at reduced blower speed until conditions permit normal control to resume. Purge modes are also used to delay heater blower operation and prevent cool air from exiting heater outlets. Selecting AUTO mode will prevent purge modes from initiating.

Actuator Calibration

After actuator replacement, actuator must be recalibrated for to ensure proper valve travel. Cycle ignition switch to ON position for 3 minutes to allow programmer and actuator(s) to recalibrate travel. For link rod adjustment see appropriate link rod adjustment procedure.

Driver Link Rod Adjustment (Dual Zone A/C System)

1. Remove right sound insulator. Remove glove box. See «GLOVE BOX»(/cadillac/eldorado/x-1992-2002/remont/automatic-hvac-system/#hvac-system-automatic) under REMOVAL & INSTALLATION. Start vehicle, and set A/C-heater control panel to 90°F (32°C) temperature setting. Set passenger temperature control to maximum heating. If outside temperature is greater than 90°F (32°C), disconnect in-vehicle temperature sensor.
2. Allow at least 45 seconds for air-mix valve actuators to reach full heat position. (Scheme 3) Gently pull driver-side air-mix valve link toward programmer until air-mix valve hits stop. Push threaded portion of link into slot of driver-side temperature valve crank.

Passenger Link Rod Adjustment (Dual Zone A/C System)

1. Remove right sound insulator. Remove glove box. See «GLOVE BOX»(/cadillac/eldorado/x-1992-2002/remont/automatic-hvac-system/#hvac-system-automatic) under REMOVAL & INSTALLATION. Pull link rod from retainer on programmer output arm. (Scheme 3) Start vehicle, and set A/C-heater control panel to 90°F (32°C) temperature setting.
2. Allow at least 45 seconds for programmer arm to reach full heat position. Set air-mix valve to maximum heat position, and snap link rod into programmer output crank retainer. (Scheme 3)

Link Rod Adjustment (Standard A/C System)

1. Remove right sound insulator. Remove glove box. See «GLOVE BOX»(/cadillac/eldorado/x-1992-2002/remont/automatic-hvac-system/#hvac-system-automatic) under REMOVAL & INSTALLATION. Pull link rod from retainer on programmer output crank arm. Start vehicle, and set A/C-heater control panel to 90°F (32°C) temperature setting.
2. Allow at least 45 seconds for programmer output crank arm to reach full heat position. Set air-mix valve to maximum heat position, and snap link rod into programmer output crank retainer. (Scheme 4)

Scheme 4

TROUBLE SHOOTING

COOLING FANS

Note. Check for, and repair any A/C DTCs before proceeding with COOLING FAN FUNCTIONAL CHECK. See ACM SELF-DIAGNOSTICS under TESTING . If DTC P1660 is set or sets during COOLING FAN SYMPTOM CHECK, DTC P1660 must be diagnosed before proceeding. See TESTS W/CODES article in ENGINE PERFORMANCE section.

When PCM commands low speed cooling fan operation, cooling fan relay No. 1 is grounded. When cooling fan relay No. 1 is grounded, a series circuit through both fans to ground is created. When PCM commands high speed cooling fan operation, all cooling fan relays are grounded. When all cooling fan relays are grounded, a parallel ground circuit is created.

Cooling fans are wired in series through series/parallel cooling fan relay No. 2. Cooling fan relay No. 2, while de-energized during low speed fan operation, provides a ground path for left side fan. When minimum cooling is needed, PCM energizes low speed relay No. 1. When maximum cooling is needed, PCM energizes all 3 relays. Left cooling fan, operates in high speed and is powered through cooling fan No. 1 and grounded through cooling fan relay No. 2. Right side cooling fan is powered through high speed fan relay No. 3 and operates in high speed.

Low speed cooling fan operation will occur when

1. A/C operation is requested.
2. Engine coolant temperature is greater than 229°F (109°C).
3. Transmission fluid temperature is greater than 302°F (150°C).
4. When ignition is turned off, if engine coolant temperature is greater than 304°F (151°C) and battery voltage is greater than 12 volts, cooling fan will stay on for about 3 minutes. When engine coolant temperature cools to less than 216°F (102°C), cooling fans will switch from low speed to off.

High speed cooling fan operation will occur when

1. Engine coolant temperature is 234°F (112°C) or more.
2. Transmission fluid temperature is greater than 302°F (150°C).

When engine coolant temperature cools to less than 229°F (109°C), cooling fans will switch from high speed to low speed.

Cooling Fan Functional Check

1. If On-Board Diagnostic (OBD) System Check has not been performed, see the TESTS W/CODES article in the ENGINE PERFORMANCE section and go to OBD SYSTEM CHECK. If OBD SYSTEM CHECK has been performed, go to next step.
2. Ensure engine coolant temperature is 41-212°F (5-100°C). Turn A/C controls to OFF position. Start and idle engine. Using scan tool, select OUTPUT TESTS. While viewing QUAD DRIVER 1 display, command all relays OFF for approximately 15 seconds and ON for approximately 15 seconds. If QUAD DRIVER 1 display does not indicate a fault, go to next step. If QUAD DRIVER 1 display indicates a fault, see DTC P1660 in the TESTS W/CODES article in the ENGINE PERFORMANCE section.
3. With engine idling, turn A/C controls to ON position and maximum cooling. If there are no DTC failures during this ignition cycle, go to next step. If there are DTC failures during this ignition cycle, go to appropriate DTC test. See «ACM SELF-DIAGNOSTICS»(/cadillac/eldorado/x-1992-2002/remont/automatic-hvac-system/#hvac-system-automatic__acm-self-diagnostics) .
4. Turn engine off and ignition switch to ON position. Ensure engine coolant temperature is less than 212°F (100°C). Using scan tool, command cooling fan relay No. 1 on, then all relays on, than all relays off. When fan relay No. 1 is on, both fans should operate at low speed. When all fan relays are commanded on, both fans should operate at high speed. When all fan relays are commanded off, both fan should not operate (unless PCM detects a fault or there is a high temperature condition). If fans do not operate as described, go to next step. If fans operate as specified, system is operating properly.
5. If only left side fan operates when cooling fan relay No. 1 is commanded on, and both fans operate when all cooling fan relays are commanded on, go to next step. If cooling fans do not operate as specified, go to step 7).
6. Repair short to ground in White wire between left side cooling fan and cooling fan relay No. 2. When repair is complete, repeat step 4).
7. If neither fan operates when cooling fan relay No. 1 is commanded on and only right side fan operates when all cooling fan relays are commanded on, go to COOLING FAN SYMPTOM CHECK NO. 1. If cooling fans do not operate as specified, go to next step.
8. If neither fan operates when cooling fan relay No. 1 is commanded on and only left side fan operates when all cooling fan relays are commanded on, go to COOLING FAN SYMPTOM CHECK NO. 2. If cooling fans do not operate as specified, go to next step.
9. If both fans operate when cooling fan relay No. 1 is commanded on and only right side fan operates when all cooling fan relays are commanded on, go to COOLING FAN SYMPTOM CHECK NO. 3. If cooling fans do not operate as specified, go to next step.
10. If both fans operate when cooling fan relay No. 1 is commanded on and only left side fan operates when all cooling fan relays are commanded on, go to COOLING FAN SYMPTOM CHECK NO. 4. If cooling fans do not operate as specified, go to next step.
11. If neither fan operates when cooling fan relay No. 1 is commanded on and neither fan operates when all cooling fan relays are commanded on, go to COOLING FAN SYMPTOM CHECK NO. 5. If cooling fans do not operate as specified, go to next step.
12. If either fan operates when all cooling fan relays are commanded off, go to DIAGNOSTIC AIDS. If cooling fans operate as specified, repeat step 4).

Cooling Fan Symptom Check No. 1

1. COOLING FAN FUNCTIONAL CHECK must be performed before proceeding. If COOLING FAN FUNCTIONAL CHECK has been performed, go to next step.
2. Disconnect left side cooling fan connector. Using scan tool, select OUTPUT TESTS and then FAN RELAYS. Turn ignition switch to ON position and command cooling fan relay No. 1 on. Using a voltmeter, measure voltage between ground and left side cooling fan connector terminal "B" (Black wire). If voltage is 10 volts or more, go to next step. If voltage is less than 10 volts, go to step 6).
3. Connect a jumper wire between left side cooling fan connector terminals (Black wire and White wire). If right side cooling fan does not operate, go to next step. If right side cooling fan operates, replace left side cooling fan. Repeat COOLING FAN FUNCTIONAL CHECK when repair is completed to ensure system is operating properly.
4. With jumper wire still connected, remove cooling fan relay No. 2, located rear of radiator, at bottom center, between cooling fans. Using a voltmeter, measure voltage between ground and cooling fan relay No. 2 connector terminal No. 30 (White wire). If voltage is 10 volts or more, go to next step. If voltage is less than 10 volts, repair open in White wire between left side cooling fan and cooling fan relay No. 2. Repeat COOLING FAN FUNCTIONAL CHECK when repair is completed to ensure system is operating properly.
5. Connect another jumper wire between cooling fan relay No. 2 connector terminals No. 30 (White wire) and No. 87A (Light Blue wire). With both jumper wires connected, if right side cooling fan operates, replace cooling fan relay No. 2. If right side cooling fan does not operate, repair open in Light Blue wire between cooling fan relay No. 2 and splice S117. See «WIRING DIAGRAMS»(/cadillac/eldorado/x-1992-2002/remont/automatic-hvac-system/#hvac-system-automatic) . Repeat COOLING FAN FUNCTIONAL CHECK when repair is completed to ensure system is operating properly.
6. Using scan tool, exit FAN RELAYS. Remove cooling fan relay No. 1, located rear of radiator, at bottom center, between cooling fans. Using a voltmeter, measure voltage between ground and cooling fan relay No. 1 connector terminal No. 30 (Red wire). If voltage is 10 volts or more, go to next step. If voltage is less than 10 volts, repair open in Red wire between cooling fan relay No. 1 and COOL FANS fuse (50-amp) located in right Maxi fuse block. Repeat COOLING FAN FUNCTIONAL CHECK when repair is completed to ensure system is operating properly.
7. Connect a jumper wire between cooling fan relay No. 1 connector terminals No. 30 (Red wire) and No. 87 (Black wire). Using a voltmeter, measure voltage between ground and left side cooling fan connector terminal "B" (Black wire). If voltage is 10 volts or more, replace cooling fan relay No. 1. If voltage is less than 10 volts, repair open in Black wire between cooling fan relay No. 1 and left side cooling fan. Repeat COOLING FAN FUNCTIONAL CHECK when repair is completed to ensure system is operating properly.

Cooling Fan Symptom Check No. 2

1. COOLING FAN FUNCTIONAL CHECK must be performed before proceeding. If COOLING FAN FUNCTIONAL CHECK has been performed, go to next step.
2. Disconnect right side cooling fan connector. Using scan tool, select OUTPUT TESTS and then FAN RELAYS. Turn ignition switch to ON position and command cooling fan relay No. 1 on. Connect a jumper wire between right side cooling fan connector terminals (Black wire and Light Blue wire). If left side cooling fan does not operate, go to next step. If left side cooling fan operates, replace right side cooling fan. Repeat COOLING FAN FUNCTIONAL CHECK when repair is completed to ensure system is operating properly.
3. With cooling fan relay No. 1 still commanded on, remove cooling fan relay No. 2, located rear of radiator, at bottom center, between cooling fans. Connect a jumper wire between cooling fan relay No. 2 connector terminals No. 30 (White wire) and No. 87A (Light Blue wire). If left side cooling fan does not operate, go to next step. If left side cooling fan operates, replace cooling fan relay No. 2. Repeat COOLING FAN FUNCTIONAL CHECK when repair is completed to ensure system is operating properly.
4. With cooling fan relay No. 2 jumper wire still connected, use a voltmeter to measure voltage between ground and right side cooling fan connector terminal "B" (Light Blue wire). If voltage is 10 volts or more, repair open in Black wire between right side cooling fan and splice S130. See «WIRING DIAGRAMS»(/cadillac/eldorado/x-1992-2002/remont/automatic-hvac-system/#hvac-system-automatic) . If voltage is less than 10 volts, repair open in Light Blue wire between right side cooling fan and cooling fan relay No. 2. Repeat COOLING FAN FUNCTIONAL CHECK when repair is completed to ensure system is operating properly.

Cooling Fan Symptom Check No. 3

1. COOLING FAN FUNCTIONAL CHECK must be performed before proceeding. If COOLING FAN FUNCTIONAL CHECK has been performed, go to next step.
2. Using scan tool, select OUTPUT TESTS and then FAN RELAYS. Turn ignition switch to ON position and command all cooling fan relays on. Remove cooling fan relay No. 2, located rear of radiator, at bottom center, between cooling fans. Measure voltage between ground and cooling fan relay No. 2 connector terminal No. 85 (Orange wire). If voltage is 10 volts or more, go to next step. If voltage is less than 10 volts, repair open in Orange wire between cooling fan relay No. 2 and splice S118. See «WIRING DIAGRAMS»(/cadillac/eldorado/x-1992-2002/remont/automatic-hvac-system/#hvac-system-automatic) . Repeat COOLING FAN FUNCTIONAL CHECK when repair is completed to ensure system is operating properly.
3. Remove cooling fan relay No. 3, located rear of radiator, at bottom center, between cooling fans. Using an ohmmeter, measure resistance of Dark Blue wire between cooling fan relay No. 2 connector terminal No. 86 and cooling fan relay No. 3 connector terminal No. 86. If resistance is 5 ohms or less, go to next step. If resistance is more than 5 ohms, repair open in Dark Blue wire between cooling fan relay No. 2 and splice S129. See «WIRING DIAGRAMS»(/cadillac/eldorado/x-1992-2002/remont/automatic-hvac-system/#hvac-system-automatic) . Repeat COOLING FAN FUNCTIONAL CHECK when repair is completed to ensure system is operating properly.
4. Reconnect cooling fan relay No. 3. With all relays still commanded on, connect a jumper wire between cooling fan relay No. 2 connector terminals No. 30 (White wire) and No. 87 (Black wire). If both cooling fans operate, replace cooling fan relay No. 2. If both cooling fans do not operate, repair open in Black wire between cooling fan relay No. 2 connector terminal No. 87 and splice S130. See «WIRING DIAGRAMS»(/cadillac/eldorado/x-1992-2002/remont/automatic-hvac-system/#hvac-system-automatic) . Repeat COOLING FAN FUNCTIONAL CHECK when repair is completed to ensure system is operating properly.

Cooling Fan Symptom Check No. 4

1. COOLING FAN FUNCTIONAL CHECK must be performed before proceeding. If COOLING FAN FUNCTIONAL CHECK has been performed, go to next step.
2. Using scan tool, select OUTPUT TESTS and then FAN RELAYS. Turn ignition switch to ON position and command all cooling fan relays on. Remove cooling fan relay No. 3, located rear of radiator, at bottom center, between cooling fans. Measure voltage between ground and cooling fan relay No. 3 connector terminal No. 85 (Orange wire). If voltage is 10 volts or more, go to next step. If voltage is less than 10 volts, repair open in Orange wire between cooling fan relay No. 2 and splice S118. See «WIRING DIAGRAMS»(/cadillac/eldorado/x-1992-2002/remont/automatic-hvac-system/#hvac-system-automatic) . Repeat COOLING FAN FUNCTIONAL CHECK when repair is completed to ensure system is operating properly.
3. Using a voltmeter, measure voltage between ground and cooling fan relay No. 3 connector terminal No. 30 (Red wire). If voltage is 10 volts or more, go to next step. If voltage is less than 10 volts, repair open in Red wire between cooling fan relay connector terminal No. 30 and COOL FANS fuse (50-amp) located in right Maxi fuse block. Repeat COOLING FAN FUNCTIONAL CHECK when repair is completed to ensure system is operating properly.
4. Remove cooling fan relay No. 3. Using an ohmmeter, measure resistance of Dark Blue wire between cooling fan relay No. 2 connector terminal No. 86 and cooling fan relay No. 3 connector terminal No. 86. If resistance is 5 ohms or less, go to next step. If resistance is more than 5 ohms, repair open in Dark Blue wire between cooling fan relay No. 3 and splice S129. See «WIRING DIAGRAMS»(/cadillac/eldorado/x-1992-2002/remont/automatic-hvac-system/#hvac-system-automatic) . Repeat COOLING FAN FUNCTIONAL CHECK when repair is completed to ensure system is operating properly.
5. Reconnect cooling fan relay No. 2. With all cooling fan relays commanded on, connect a jumper wire between cooling fan relay No. 3 connector terminals No. 30 (Red wire) and No. 87 (Light Blue wire). If right cooling fan operates, replace cooling fan relay No. 3. If right cooling fan does not operate, repair open in Light Blue wire between cooling fan relay No. 3 and splice S117. See «WIRING DIAGRAMS»(/cadillac/eldorado/x-1992-2002/remont/automatic-hvac-system/#hvac-system-automatic) . Repeat COOLING FAN FUNCTIONAL CHECK when repair is completed to ensure system is operating properly.

Cooling Fan Symptom Check No. 5

1. COOLING FAN FUNCTIONAL CHECK must be performed before proceeding. If COOLING FAN FUNCTIONAL CHECK has been performed, go to next step.
2. Check condition of COOL FANS fuse (50-amp) located in right Maxi fuse block. If fuse is okay, go to next step. If fuse is not okay, turn ignition switch to LOCK position and replace fuse. If fuse does not blow, go to step 4). If fuse blows, repair short to ground in Red wire between fuse and either cooling fan relay No. 1 or 3. Repeat COOLING FAN FUNCTIONAL CHECK when repair is completed to ensure system is operating properly.
3. Remove cooling fan relay No. 1. Using a voltmeter, measure voltage between ground and cooling fan relay No. 1 connector terminal No. 30 (Red wire). If voltage is 10 volts or more, repair open in Black wire between splice S130 and ground or poor ground connection. See «WIRING DIAGRAMS»(/cadillac/eldorado/x-1992-2002/remont/automatic-hvac-system/#hvac-system-automatic) . If voltage is less than 10 volts, repair open in Red wire between COOL FANS fuse and cooling fan relays No. 1 and No. 3. Repeat COOLING FAN FUNCTIONAL CHECK when repair is completed to ensure system is operating properly.
4. Turn ignition switch to ON position. Using scan tool, select OUTPUT TESTS and the FAN RELAYS. Command fan relay No. 1 on. If COOL FANS fuse (50-amp) does not blow, go to next step. If COOL FANS fuse (50-amp) blows, repair short to ground in Black wire between cooling fan relay No. 1 and left cooling fan. Repeat COOLING FAN FUNCTIONAL CHECK when repair is completed to ensure system is operating properly.
5. Using scan tool, command all cooling fan relays on. If COOL FANS fuse (50-amp) does not blow, no fault is found and system is operating properly. If fuse blows, go to next step.
6. Using scan tool, exit FAN RELAYS. Replace COOL FANS fuse (50-amp). Using scan tool, select FAN RELAYS and command cooling fan relay No. 1 on. If left cooling fan is operating, replace right cooling fan. If left cooling fan is not operating, replace left cooling fan. Repeat COOLING FAN FUNCTIONAL CHECK when repair is completed to ensure system is operating properly.

Diagnostic Aids

If cooling fans operate when commanded OFF and DTC P1660 is not set, either a cooling fan relay is stuck ON or a cooling fan circuit is shorted to battery voltage. Repeat COOLING FAN FUNCTIONAL CHECK when repair is completed to ensure system is operating properly.

PCM CONTROLLED A/C DIAGNOSIS

Note. Since many Diagnostic Trouble Codes (DTCs) cause PCM to disable A/C compressor operation, any DTCs must be repaired and cleared before proceeding. See the TESTS W/CODES article in the ENGINE PERFORMANCE section and go to OBD SYSTEM CHECK.

When A/C-Heater Programmer (ACM) requests A/C operation from Powertrain Control Module (PCM), PCM will ground A/C relay. When A/C relay is grounded A/C compressor clutch is energized. PCM will disable or inhibit A/C compressor operation during high power steering load, engine is not running, engine is running at wide open throttle, ambient temperature is less than 40°F (4°C) or certain PCM DTCs set. A/C compressor will also be disengaged during engine cranking in colder weather to prevent A/C slugging.

PCM Controlled A/C Check

1. If On-Board Diagnostic (OBD) System Check has not been performed, see the TESTS W/CODES article in the ENGINE PERFORMANCE section and go to OBD SYSTEM CHECK. If OBD SYSTEM CHECK has been performed, go to next step.
2. Connect scan tool. Start engine and bring to idle. Turn A/C on and select MAX cold and AUTO. Observe scan tool for A/C relay status. If scan tool indicates A/C relay is on, PCM control is okay, go to «ACM SELF-DIAGNOSTICS»(/cadillac/eldorado/x-1992-2002/remont/automatic-hvac-system/#hvac-system-automatic__acm-self-diagnostics) under TESTING. If scan tool indicates A/C relay is off, go to next step.
3. PCM is not allowing A/C clutch operation (DTCs set or low ambient temperature) or PCM may not have received a request for A/C operation. PCM control of A/C compressor clutch can be verified by turning engine off and ignition switch to OFF position. Using scan tool, command A/C compressor clutch on and off. Listen for A/C compressor clutch to engage and disengage. If PCM control is verified, clutch engages and disengages, go to «ACM SELF-DIAGNOSTICS»(/cadillac/eldorado/x-1992-2002/remont/automatic-hvac-system/#hvac-system-automatic__acm-self-diagnostics) under TESTING. If PCM control is not verified, see the TESTS W/CODES article in the ENGINE PERFORMANCE section and go to OBD SYSTEM CHECK.
4. Remove A/C compressor clutch relay in engine compartment fuse block, located in front of left front strut tower. Start engine and allow to idle. Turn A/C on. Using a test light connected to battery voltage, probe A/C compressor clutch relay connector terminal D1 (Dark Green/White wire). If test light does not come on, go to next step. If test light comes on, PCM control is okay, go to «ACM SELF-DIAGNOSTICS»(/cadillac/eldorado/x-1992-2002/remont/automatic-hvac-system/#hvac-system-automatic__acm-self-diagnostics) under TESTING.
5. Turn engine off and ignition off. Disconnect PCM Blue 80-pin connector C1. Using an ohmmeter, measure resistance of Dark Green/White wire between PCM connector terminal No. 27 and A/C compressor clutch relay connector terminal D1. If resistance is 5 ohms or less, go to next step. If resistance is more than 5 ohms, repair open in Dark Green/White wire. Ensure system is operating properly.
6. Check for an open, or loose or disconnected terminals at PCM connector terminal No. 27 and A/C compressor clutch relay connector terminal D1 (Dark Green/White wire). If connectors and terminals are okay, replace PCM. Ensure system is operating properly.

TROUBLE SHOOTING CHARTS

Note. Body Control Module (BCM) may be referred as Platform Zone Module (PZM) in trouble shooting charts.

TROUBLE SHOOTING CHART 1 - NO COMPRESSOR OPERATION

Compressor clutch coil receives power through A/C relay, and is grounded at ground connection G100. See WIRING DIAGRAMS . Before diagnosing, ensure DTCs are corrected and cleared. An open power steering switch or faulty throttle position sensor could prevent A/C clutch engagement.

Note. Test numbers refer to numbers on diagnostic chart.

1. This step checks whether fault lies in output or input side of PCM.
2. This step checks A/C relay switch contacts.
3. This step checks if A/C relay is receiving power on circuit No. 2340 (Orange wire) from A/C COMP fuse (10-amp).
4. This step checks if an open exists in compressor clutch power circuit No. 59 (Dark Green wire).
5. This step checks if compressor clutch is faulty, or if an open exists in compressor clutch ground circuit No. 350 (Black wire).
6. This step checks A/C relay coil.
7. This step checks whether an open exists in circuit No. 603 (Dark Green wire) between pressure switches and ACM; circuit No. 604 (Dark Blue wire) between compressor clutch relay and ACM, and relay and high pressure switch; or circuit No. 459 (Pink wire) between ECS fuse and PCM.

Scheme 5

TROUBLE SHOOTING CHART 2 - NO BLOWER OPERATION OR IMPROPER BLOWER SPEED

Airflow is controlled by modulating commanded blower motor voltage. Blower speed is a function of the program number when it is under automatic control. Adjustments are made based on vehicle speed, coolant temperature, and sun load sensor. Special cases may override normal operation.

If blower is inoperative in normal operation, but operates properly in override, the Instrument Panel Cluster (IPC) or data line between IPC and A/C-Heater Programmer (ACM) may be faulty.

Note. Test numbers refer to numbers on diagnostic chart.

1. This step checks if blower is receiving a signal from programmer.
2. This step checks output from programmer and input to motor. If signals are similar, a problem with blower motor is indicated.
3. This step checks for possible problems with sensor inputs.

Scheme 6

Scheme 7

TROUBLE SHOOTING CHART 3 - BLOWER ON CONTINUOUSLY

Airflow is controlled by modulating commanded blower motor voltage. Blower speed is a function of the program number when it is under automatic control. Adjustments are made based on vehicle speed, coolant temperature, and sun load sensor. Special cases may override normal operation.

If blower is inoperative in normal operation, but operates properly in override, the Instrument Panel Cluster (IPC) or data line between IPC and A/C-Heater Programmer (ACM) may be faulty.

Scheme 8

Scheme 9

Scheme 10

Scheme 11

TROUBLE SHOOTING CHART 5 - IMPROPER AIR DELIVERY

A/C-Heater Programmer (ACM) will direct blended air in one of several air delivery modes. Side window outlets receive airflow during all modes of operation. ACM delivers airflow to other outlets by energizing specific vacuum valves, feeding appropriate mode valve actuator combination. ACM determines proper air delivery mode, based upon current program number, control panel setting, set temperature, low side temperature, coolant temperature, outside air temperature, and sun load sensor.

Note. Test numbers refer to numbers on diagnostic chart.

1. This step checks air inlet valve (door).
2. Checks down part of up-down valve (door).
3. Checks up part of up-down valve (door).
4. Checks A/C side of A/C-defrost valve (door).
5. Checks defrost side of A/C-defrost valve (door).

Scheme 12

Scheme 13

TROUBLE SHOOTING CHART 7 - REAR A/C BLOWER SPEED INCORRECT (ELDORADO & SEVILLE)

Power from fuse is applied to blower, and ground is supplied through switch. Blower speed is controlled by varying circuit current with a series of 3 resistors. ACM receives a feedback signal but has no bearing on rear blower operation.

Note. Test numbers refer to numbers on diagnostic chart.

1. This step checks for poor ground or poor feed circuit.
2. This step determines if resistor module is faulty.
3. This step distinguishes between faulty wiring or faulty switch.

Scheme 14

Scheme 15

TROUBLE SHOOTING CHART 8 - REAR A/C BLOWER INOPERATIVE (ELDORADO & SEVILLE)

Power from fuse is applied to blower, and ground is supplied through switch. Blower speed is controlled by varying blower circuit current using a series of 3 resistors contained in a module. ACM receives a feedback signal but has no bearing on rear blower operation.

Note. Test numbers refer to numbers on diagnostic chart.

1. If continuity exists through circuit No. 52 (Orange wire), circuit No. 850 (Black wire), and the HI position of the switch, reading will be approximately zero. With decreasing blower speeds, the blower ground path is through increasing resistance, and results in increasing voltage at splice S345 on circuit No. 52. Battery voltage should be read in OFF, or if no ground path exists.
2. If a resistor is open, all terminals beyond the break will be open also. If grounding terminal "E" at the switch connector operates the blower motor, the fault is in the switch or wiring to the switch.

Scheme 16

TROUBLE SHOOTING CHART 9 - REAR WINDOW & OUTSIDE MIRRORS DEFOGGER ON CONTINUOUSLY

Rear defogger system consists of defogger relay, rear defogger grid, Body Control Module (BCM), outside mirror defoggers, instrument panel cluster and related fuses and wiring. HTD MIR fuse (10-amp) provides battery voltage for outside mirror defoggers. REAR DEFOG fuse (30-amp) provides battery voltage for rear window defogger grid.

When IPC/CCP receives an engine running confirmation from PCM, the defogger ON-LED illuminates and PZM is commanded to turn defoggers on. PZM provides ground for defogger relay. IPC times operation initially for 10 minutes, and then commands PZM to deactivate relay ground. Additional requests for rear defogger are for 5-minute intervals until a new ignition cycle occurs.

Scheme 17

Scheme 18

TROUBLE SHOOTING CHART 10 - REAR WINDOW & OUTSIDE MIRRORS DEFOGGER INOPERATIVE

Rear defogger system consists of defogger relay, rear defogger grid, Body Control Module (BCM), outside mirror defoggers, instrument panel cluster and related fuses and wiring. HTD MIR fuse (10-amp) provides battery voltage for outside mirror defoggers. REAR DEFOG fuse (10-amp) provides battery voltage for rear window defogger grid.

When IPC/CCP receives an engine running confirmation from PCM, the defogger ON-LED illuminates and PZM is commanded to turn defoggers on. PZM provides ground for defogger relay. IPC times operation initially for 10 minutes, and then commands PZM to deactivate relay ground. Additional requests for rear defogger are for 5-minute intervals until a new ignition cycle occurs.

Scheme 19

TROUBLE CODE CHART ACM DTC B1310 - OUTSIDE AIR TEMPERATURE SENSOR OPEN CIRCUIT

Outside air temperature sensor is a thermistor which controls signal voltage to ACM. ACM applies a voltage to sensor on circuit No. 735. When sensor is cold, its resistance is high, and ACM will receive a high signal voltage at pin C8. As sensor warms, its resistance decreases, and signal voltage is pulled low through sensor ground circuit No. 407. This signal voltage will vary between 5 volts (open circuit) and zero volts (short circuit).

Test Conditions

Ignition on.

Failure Conditions

If ambient temperature drops below approximately -36°F (-38°C), ignore code.

Actions Taken

1. Display "--" on IPC or CCP (with dual zone A/C-heater system) temperature display.
2. A default value of 60°F (15°C) will be used to allow operation of climate control system. NOTE: Test numbers refer to numbers on diagnostic chart.
3. Scan tool displays outside temperature. Using jumper wire, connect harness connector to determine whether wiring or sensor is faulty.

Note On Intermittents

If an intermittent DTC B1310 is set, connect scan tool, select ACM DATA LIST, OPEN/SHORTS DATA and note reading. Manipulate related wiring while observing scan tester. If failure is induced, reading will jump. Check for poor terminal contact, obstructed sensor, or defective sensor.

Scheme 20

Scheme 21

TROUBLE CODE CHART ACM DTC B1311 - OUTSIDE AIR TEMPERATURE SENSOR SHORT CIRCUIT

Outside air temperature sensor is a thermistor which controls signal voltage to ACM. ACM applies voltage to sensor on circuit No. 735. When sensor is cold, its resistance is high, and ACM will receive a high signal voltage at pin C8. As sensor warms, its resistance decreases, and signal voltage is pulled low through sensor ground circuit No. 407. This signal voltage will vary between 5 volts (open circuit) and zero volts (short circuit).

Ignition on.

If ambient temperature drops below approximately -36°F (-38°C), ignore code.

1. Display "--" on IPC or CCP (with dual zone A/C-heater system) temperature display.
2. A default value of 60°F (15°C) will be used to allow operation of climate control system. NOTE: Test numbers refer to numbers on diagnostic chart.
3. Scan tool displays outside temperature. Disconnecting sensor will determine whether wiring or sensor is faulty.
4. Test light should not light. Test light is used to provide resistance.

If an intermittent DTC B1311 is set, connect scan tool, select ACM SNAPSHOT DATA for outside air temperature sensor, and note value. Manipulate related wiring while observing scan tester. If failure is induced, reading will jump. Check for poor terminal contact, obstructed sensor, or defective sensor.

Scheme 22

TROUBLE CODE CHART ACM DTC B1312 - A/C HIGH-SIDE TEMP. SENSOR OPEN CIRCUIT

High-side temperature sensor is a thermistor which controls signal voltage to ACM. ACM applies voltage to sensor on circuit No. 732. When sensor is cold, its resistance is high, and ACM will receive a high signal voltage at pin C5. As sensor warms, its resistance decreases, and signal voltage is pulled low through sensor ground circuit No. 407. This signal voltage will vary between 5 volts (open circuit) and zero volts (short circuit).

1. Ignition on. DTC B1310 is not set.
2. Ambient temperature is greater than 30°F (-1°C).

1. High cooling fans operate when A/C compressor operation is possible.
2. A default value of 144°F (79°C) will be used to continue system operation. NOTE: Test numbers refer to numbers on diagnostic chart.
3. Scan tool displays high-side temperature. Using jumper wire, connect harness connector to determine whether wiring or sensor is faulty.

On some vehicles, DTC may set intermittently if sensor temperature falls below 30°F (-1°C). DTC becomes history after sensor temperature increases.

If an intermittent DTC B1312 is set, use scan tool to select ACM DATA LIST, OPEN/SHORTS DATA and note reading. Manipulate related wiring while observing scan tester. If failure is induced, reading will jump. Check for poor terminal contact, obstructed sensor, or defective sensor.

Scheme 23

Scheme 24

TROUBLE CODE CHART ACM DTC B1313 - A/C HIGH-SIDE TEMP. SENSOR SHORT CIRCUIT

High-side temperature sensor is a thermistor which controls signal voltage to ACM. ACM applies voltage to sensor on circuit No. 732. When sensor is cold, its resistance is high, and ACM will receive a high signal voltage at pin C5. As sensor warms, its resistance decreases, and signal voltage is pulled low through sensor ground circuit No. 407. This signal voltage will vary between 5 volts (open circuit) and zero volts (short circuit).

1. Ignition on. DTC B1310 is not set.

1. High cooling fans operate when A/C compressor operation is possible.
2. A default value of 144°F (79°C) will be used to continue system operation. NOTE: Test numbers refer to numbers on diagnostic chart.
3. Scan tool displays high-side temperature. Disconnecting sensor connector will determine whether wiring or sensor is faulty.
4. Test light should not light. Test light is used to provide resistance.

On some vehicles, DTC may set intermittently if sensor temperature falls below 30°F (-1°C). DTC becomes history after sensor temperature increases.

If an intermittent DTC B1313 is set, use scan tool to select ACM DATA LIST, OPEN/SHORTS DATA and note reading. Manipulate related wiring while observing scan tester. If failure is induced, reading will jump. Check for poor terminal contact, obstructed sensor, or defective sensor.

Scheme 25

TROUBLE CODE CHART ACM DTC B1314 - EVAPORATOR INLET TEMP. SENSOR OPEN CIRCUIT

Evaporator inlet temperature sensor is a thermistor which controls signal voltage to ACM. ACM applies voltage to sensor on circuit No. 731. When sensor is cold, its resistance is high, and ACM will receive a high signal voltage at pin D15. As sensor warms, its resistance decreases, and signal voltage is pulled low through sensor ground circuit No. 407. This signal voltage will vary between 5 volts (open circuit) and zero volts (short circuit).

1. Ignition on.

1. A/C compressor clutch is not allowed to engage.
2. IPC displays SERVICE A/C SYSTEM - A/C COMPRESSOR OFF.
3. A default temperature reading of 43°F (6°C) will be implemented. NOTE: Test numbers refer to numbers on diagnostic chart.
4. Scan tool displays low-side temperature. Using jumper wire, connect harness connector to determine whether wiring or sensor is faulty.

If intermittent DTC B1314 is set, use scan tool to select ACM DATA LIST, OPEN/SHORTS DATA and NOTE READING. Manipulate related wiring while observing scan tester. If failure is induced, reading will jump. Check for poor terminal contact, obstructed sensor, or defective sensor.

Scheme 26

TROUBLE CODE CHART ACM DTC B1315 - EVAPORATOR INLET TEMP. SENSOR SHORT CIRCUIT

Evaporator inlet temperature sensor is a thermistor which controls signal voltage to ACM. ACM applies voltage to sensor on circuit No. 731. When sensor is cold, its resistance is high, and ACM will receive a high signal voltage at pin D15. As sensor warms, its resistance decreases, and signal voltage is pulled low through sensor ground circuit No. 407. This signal voltage will vary between 5 volts (open circuit) and zero volts (short circuit).

1. Ignition on.

1. A/C compressor clutch is not allowed to engage.
2. IPC displays SERVICE A/C SYSTEM - A/C COMPRESSOR OFF.
3. A default temperature reading of 43°F (6°C) will be implemented. NOTE: Test numbers refer to numbers on diagnostic chart.
4. Scan tool displays low-side temperature. Disconnecting sensor connector will determine whether wiring or sensor is faulty.
5. Test light should not light. Test light is used to provide resistance.

If an intermittent DTC B1315 is set, use scan tool to select ACM DATA LIST, OPEN/SHORTS DATA and note reading. Manipulate related wiring while observing scan tester. If failure is induced, reading will jump. Check for poor terminal contact, obstructed sensor, or defective sensor.

Scheme 27

TROUBLE CODE CHART ACM DTC B1316 - IN-CAR TEMP. SENSOR OPEN CIRCUIT

In-car temperature sensor is a thermistor which controls signal voltage to ACM. ACM applies voltage to sensor on circuit No. 734. When sensor is cold, its resistance is high, and ACM will receive a high signal voltage at pin D9. As sensor warms, its resistance decreases, and signal voltage is pulled low through sensor ground circuit No. 407. This signal voltage will vary between 5 volts (open circuit) and zero volts (short circuit).

1. Ignition on.
2. Outside air temperature is above -20°F (-29°C).
3. DTC B1310 and B1311 are not set.

1. A substitute temperature reading of 75°F (24°C) will be used to continue system operation. NOTE: Test numbers refer to numbers on diagnostic chart.
2. Scan tool displays in-car temperature. Disconnecting harness connector will determine whether wiring or sensor is faulty.

If an intermittent DTC B1316 is set, use scan tool to select ACM DATA LIST, OPEN/SHORTS DATA and note reading.

Manipulate related wiring while observing scan tester. If failure is induced, reading will jump. Check for poor terminal contact, obstructed sensor, or defective sensor.

Scheme 28

TROUBLE CODE CHART ACM DTC B1317 - IN-CAR TEMP SENSOR SHORT CIRCUIT

In-car temperature sensor is a thermistor which controls signal voltage to ACM. ACM applies voltage to sensor on circuit No. 734. When sensor is cold, its resistance is high, and ACM will receive a high signal voltage at pin D9. As sensor warms, its resistance decreases, and signal voltage is pulled low through sensor ground circuit No. 407. This signal voltage will vary between 5 volts (open circuit) and zero volts (short circuit).

1. Ignition on.
2. Outside air temperature is above -20°F (-29°C).
3. DTC B1310 and B1311 are not set.

1. A substitute temperature reading of 75°F (24°C) will be used to continue system operation. NOTE: Test numbers refer to numbers on diagnostic chart.
2. Scan tool displays in-car temperature. Disconnecting harness connector will determine whether wiring or sensor is faulty.
3. Test light should not light. Test light is used to provide resistance.

If an intermittent DTC B1317 is set, use scan tool to select ACM SNAPSHOT DATA for in-car temperature sensor and note value.

Manipulate related wiring while observing scan tester. If failure is induced, reading will jump. Check for poor terminal contact, obstructed sensor, or defective sensor.

Scheme 29

TROUBLE CODE CHART ACM DTC B1318 - SUNLOAD SENSOR OPEN CIRCUIT

Sunload sensor uses a photo diode to control a signal voltage to ACM. This photo diode is different from thermistor-type sensors, and resistance measurements will not produce accurate results. ACM monitors voltage on circuit No. 590 to sensor. When sensor is in direct light, ACM will receive a low signal voltage at pin C7. As sensor becomes shaded, signal voltage increases. This signal voltage varies between 5 volts (open circuit) and zero volts (short circuit).

Ignition on.

1. A substitute value of 250 counts will be implemented to continue system operation. NOTE: Test numbers refer to numbers on diagnostic chart.
2. Scan tool displays sunload reading. Disconnecting sensor harness connector and connecting a jumper wire between connector terminals will determine whether wiring or sensor is faulty.

If an intermittent DTC B1318 is set, use scan tool to select ACM DATA LIST, OPEN/SHORTS DATA and note reading.

Manipulate related wiring while observing scan tester. If failure is induced, reading will jump. Check for poor terminal contact, obstructed sensor, or defective sensor.

Scheme 30

TROUBLE CODE CHART ACM DTC B1319 - SUNLOAD SENSOR SHORT CIRCUIT

Sunload sensor uses a photo diode to control signal voltage to ACM. This photo diode is different from thermistor-type sensors, and resistance measurements will not produce accurate results. ACM monitors voltage on circuit No. 590 to sensor. When sensor is in direct light, ACM will receive a low signal voltage at pin C7. As sensor becomes shaded, signal voltage increases. This signal voltage varies between 5 volts for open circuit and zero volts for short circuit.

Ignition on.

1. A substitute value of 250 counts will be implemented to allow continued operation of system. NOTE: Test numbers refer to numbers on diagnostic chart.
2. Scan tool displays sunload reading. Disconnecting sensor harness connector will determine whether wiring or sensor is faulty.
3. Test light should not light. Test light is used to provide resistance.

If an intermittent DTC B1319 is set, use scan tool to select ACM DATA LIST, OPEN/SHORTS DATA and note reading.

Manipulate related wiring while observing scan tester. If failure is induced, reading will jump. Check for poor terminal contact, obstructed sensor, or defective sensor.

Scheme 31

TROUBLE CODE CHART ACM DTC B1340 - AIR-MIX DOOR NO. 1 CIRCUIT PROBLEM

ACM supplies voltage to an internal motor, which drives air-mix door. ACM monitors air-mix door position feedback from a sensor on motor. If mix door is requested to move but feedback voltage does not change, ACM stores DTC B1340. If air-mix door feedback indicates it is near hot or cold extreme, DTC will not set. Operation of air-mix door can be evaluated through functional check described in step 1) of diagnostic chart.

1. Commanded mix door greater than zero percent.
2. Commanded mix door position less than 76 percent.

Actual mix door position is not within 3 percent of commanded mix door position within approximately 60 seconds.

None.

Note. Test numbers refer to numbers on diagnostic chart.

1. By observing air-mix door position sensor feedback value and its difference from air-mix door commanded position value, scan tool allows for direct control of air-mix door.
2. These readings indicate if an internal ACM fault exists in air-mix door sensor feedback.
3. If door is not stuck, ensure smooth operation before replacing ACM.

If an intermittent DTC B1340 is set, use scan tool to select ACM SNAPSHOT DATA for air-mix door No. 1. Note value of feedback and commanded position. While monitoring feedback value, use scan tool override function to command door to positions specified. See ACTUATOR table at bottom of diagnostic chart. Without turning ignition off, physically inspect mix door linkage for any obstruction at these positions.

Scheme 32

Scheme 33

TROUBLE CODE CHART ACM DTC B1341 - AIR-MIX DOOR NO. 2 CIRCUIT PROBLEM

ACM supplies voltage to an internal motor, which drives air-mix door. ACM monitors air-mix door position feedback from a sensor on motor. If mix door is requested to move but feedback voltage does not change, ACM stores DTC B1341. If air-mix door feedback indicates it is near hot or cold extreme, DTC will not set. Operation of air-mix door can be evaluated through functional check described in step 1).

1. Commanded mix door greater than zero percent.
2. Commanded mix door position less than 76 percent.

Actual mix door position not within 3 percent of commanded mix door position within approximately 60 seconds.

None.

Note. Test numbers refer to numbers on diagnostic chart.

1. By observing air-mix door position sensor feedback value and its difference from air-mix door commanded position value, scan tool allows for direct control of air-mix door.
2. These readings indicate whether an internal ACM fault exists in air-mix door sensor feedback.
3. If door is not stuck, ensure smooth operation before replacing ACM.

If an intermittent DTC B1341 is set, use scan tool to select ACM SNAPSHOT DATA for air-mix door No. 2 and note value of feedback and commanded position. While monitoring feedback value, use scan tool override function to command door to positions specified. See ACTUATOR table at bottom of diagnostic chart. Without turning ignition off, physically inspect mix door linkage for any obstruction at these positions.

Scheme 34

TROUBLE CODE CHART ACM DTC B1347 - VERY LOW A/C REFRIGERANT WARNING

In the process of controlling compressor clutch, ACM monitors certain inputs for indication of low refrigerant charge. If system refrigerant charge should fall below approximately 1/3 of its capacity, ACM is capable of detecting this condition and will display a warning message to warn operator.

ACM determines state of charge by monitoring temperature change in low-side temperature sensor during initial moments of each compressor engagement. This temperature drop is referenced in a table in ACM as a function of outside air temperature. If refrigerant charge is too low, refrigerant will boil instantaneously after it passes through orifice tube, creating a rapid large change in low-side temperature reading. If temperature change is too great, a very low refrigerant counter in ACM is incremented. After several repeated incidents, ACM will set DTC B1347, and VERY LOW REFRIGERANT - A/C COMPRESSOR OFF is displayed on Driver Information Center (DIC). If DTC B1347 is set, compressor clutch will disengage and remain disengaged until DTC is cleared.

Low-side refrigerant temperature drops too quickly during several compressor cycles.

1. Disables A/C compressor until DTC is cleared.
2. Displays VERY LOW A/C REFRIGERANT - A/C COMPRESSOR OFF message. NOTE: Test numbers refer to numbers on diagnostic chart.
3. Checks for intermittent open or short in pressure switch circuit.
4. Checks for restriction within refrigerant system.
5. An offset in ACM temperature sensor's actual outside or low-side may trigger a false DTC. After leaving vehicle, preferably overnight, in a shaded, cold environment, enter diagnostics without starting engine. All listed sensor readings should be within 4°F (2°C) of each other.
6. Recover refrigerant and charge A/C system.

REFRIGERANT TEMPERATURE TO PRESSURE CONVERSION

Scheme 35

TROUBLE CODE CHART ACM DTC B1348 - VERY LOW A/C REFRIGERANT PRESSURE

In the process of controlling compressor clutch, ACM monitors certain inputs for indication of low refrigerant charge. ACM monitors normally closed low refrigerant pressure switch at pin D14. Status of low pressure switch is checked prior to compressor engagement. If switch is open, ACM sets DTC B1348, and VERY LOW REFRIGERANT - A/C COMPRESSOR OFF is displayed on Driver Information Center (DIC). If DTC B1348 is set, compressor clutch will disengage and remain disengaged until DTC is cleared.

1. Low refrigerant pressure switch remains open for several minutes.
2. Vehicle must be traveling more than 30 MPH for at least 30 seconds for DTC to set. This DTC may never set at idle or in city traffic.

1. Disables A/C compressor until DTC is cleared.
2. Displays VERY LOW A/C REFRIGERANT - A/C COMPRESSOR OFF message.

Note. Test numbers refer to numbers on diagnostic chart.

1. Checks current state of low pressure switch.
2. Checks circuits to low pressure switch.
3. Checks refrigerant system pressure.
4. Checks for a restriction in refrigerant system.
5. Checks for intermittent short or open

Scheme 36

Scheme 37

TROUBLE CODE CHART ACM DTC B1350 - ENGINE COOLANT TEMP. TOO HIGH

DTC B1350 is designed to disengage A/C compressor clutch if coolant temperature exceeds 258°F (126°C). ACM receives coolant temperature information from PCM over class 2 serial data line. While DTC B1350 is current, IPC will display ENGINE HOT - A/C COMPRESSOR OFF warning on Driver Information Center (DIC).

Trouble Shooting Hints

Ensure PCM is operating properly. Refer to the TESTS W/CODES article in the ENGINE PERFORMANCE section. If PCM is operating properly, replace ACM. Ensure system is operating properly.

TROUBLE CODE CHART ACM DTC B1982 - SOURCE/BATTERY VOLTAGE HIGH

DTC B1982 will set if ignition is on, source/battery voltage is greater than 16 volts for 2 seconds. DTC may set if vehicle has been placed on a battery charger for a long period of time.

Using scan tool, check battery voltage with engine at normal operating temperature. If displayed battery voltage is less than 16 volts, replace ACM. If displayed battery voltage is more than 16 volts, repair charging system. Ensure system is operating properly. If charging system voltage is a suspected cause, check other modules for a set DTC B1982 for confirmation.

TROUBLE CODE CHART ACM DTC B1983 - SOURCE/BATTERY VOLTAGE LOW

DTC B1983 will set if ignition is on, engine speed is more than 1500 RPM, source/battery voltage is less than 9.5 volts for 2 seconds. If source/battery voltage is too low, class 2 serial data bus will not operate, causing false class 2 serial data DTCs. DTC B1983 should not set if DTC B1981 (BATTERY VOLTAGE LOW - ENGINE RUNNING) is set. DTC B1983 will set if battery voltage drains to a level that ACM can no longer operate properly.

1. Using scan tool, check battery voltage with engine at normal operating temperature. If displayed voltage is less than 10 volts, go to next step. If displayed battery voltage is more than 10 volts, replace ACM. Ensure system is operating properly.
2. Using a voltmeter, measure voltage between ground and ACM connector terminal C3 (Orange wire). If voltage is less than 10 volts, check for an open or short to ground in Orange wire. If Orange wire is okay, check charging system. If voltage is more than 10 volts, replace ACM. Ensure system is operating properly.

TROUBLE CODE CHART ACM/CCP DTC U1016 - LOSS OF PCM SERIAL COMMUNICATIONS

DTC U1016 will set if ignition is on and ACM has lost data communication with PCM. Diagnosis of this DTC is dependent upon other system symptoms (DTCs) present with DTC U1016.

Ignition on.

Open circuit.

Action Taken

Set DTC U1016.

1. Using scan tool, attempt to establish communications with PCM.
2. Check for an open or short to power or ground on circuit No. 1807 (Purple wire).
3. Ensure PCM is connected to power and ground.
4. If multiple class 2 DTCs are current, check circuit No. 1807 (Purple wire) for short to ground or voltage. See the BODY CONTROL MODULE article in the ACCESSORIES/SAFETY EQUIPMENT section.
5. Ensure PCM is operating properly. See the TESTS W/CODES article in the ENGINE PERFORMANCE section. If PCM is operating properly, replace ACM. Ensure system is operating properly.
6. DTC P1605 (PCM loss of HVAC serial data communication) may also be present. This indicates PCM and ACM were functional when DTC was set, but could not communicate with each other. See the TESTS W/CODES article in the ENGINE PERFORMANCE section.

Scheme 38

TROUBLE CODE CHART ACM/CCP DTC U1064 - LOSS OF PZM SERIAL DATA COMMUNICATIONS

DTC U1064 will set if ignition is on and ACM has lost data communication with Body Control Module (BCM). Diagnosis of this code is dependent upon other system symptoms (DTCs) present with DTC U1064.

Ignition on.

Open circuit.

Set DTC U1064.

1. Using scan tool, attempt to establish communications with PZM.
2. Check for an open or short to power or ground on circuit No. 1807(Purple wire).
3. Ensure PZM is connected to power and ground.
4. DTC U1153 (loss of CCP serial data communications) may also be present. This indicates PZM and CCP were functional when DTC was set, but could not communicate with each other. See the BODY CONTROL MODULE article in the ACCESSORIES/SAFETY EQUIPMENT section.
5. If multiple class 2 DTCs are current, check for short to ground or voltage on circuit No. 1807 (Purple wire). See the BODY CONTROL MODULE article in the ACCESSORIES/SAFETY EQUIPMENT section.
6. Ensure PZM is operating properly. See the BODY CONTROL MODULE article in the ACCESSORIES/SAFETY EQUIPMENT section. If PZM is operating properly, replace ACM or CCP, depending upon which component has set a DTC and is being diagnosed.

TROUBLE CODE CHART ACM/CCP DTC U1096 - LOSS OF IPC SERIAL DATA COMMUNICATIONS

DTC U1096 will set if ignition is on and ACM or CCP has lost data communication with Instrument Panel Cluster (IPC). This DTC should be seen only as a history DTC. If communications are currently inoperative, ACM or CCP will not be able to communicate with IPC to display DTC. Diagnosis of this code is dependent upon other system symptoms (DTCs) present with DTC U1096.

Ignition on.

Open circuit.

Set DTC U1096.

1. Using scan tool, attempt to establish communications with IPC.
2. Check for an open or short to power or ground on circuit No. 1807 (Purple wire).
3. Ensure IPC is connected to power and ground.
4. IPC DTC U1152 (loss of ACM serial data communications) or IPC DTC U1153 (loss of CCP serial data communications) may be present with this DTC. This indicates PZM and ACM were functional when DTC was set, but could not communicate with each other. See the BODY CONTROL MODULE article in the ACCESSORIES/SAFETY EQUIPMENT section.
5. If multiple Class 2 DTCs are current, check for short to ground or voltage on circuit No. 1807 (Purple wire). See the BODY CONTROL MODULE article in the ACCESSORIES/SAFETY EQUIPMENT section.

TROUBLE CODE CHART - CCP DTC U1152 - CCP LOSS OF ACM SERIAL DATA COMMUNICATIONS

DTC U1152 will set if ignition is on and CCP has lost data communication with ACM.Diagnosis of this code is dependent upon other system symptoms (DTCs) present with DTC U1152.

Ignition on.

Open circuit.

Set DTC U1152.

1. Using scan tool, attempt to establish communications with ACM.
2. Check for an open or short to power or ground on circuit No. 1807 (Purple wire).
3. Ensure ACM is connected to power and ground.
4. ACM DTC U1153 (loss of CCP serial data communications) may be present with this DTC. This indicates CCP and ACM were functional when DTC was set, but could not communicate with each other.
5. If multiple class 2 DTCs are current, check for short to ground or voltage on circuit No. 1807 (Purple wire). See the BODY CONTROL MODULE article in the ACCESSORIES/SAFETY EQUIPMENT section.

TROUBLE CODE CHART ACM DTC U1153 - ACM LOSS OF CCP SERIAL DATA COMMUNICATIONS

DTC U1153 will set if ignition is on and ACM has lost data communication with CCP. Diagnosis of this DTC is dependent upon other system symptoms (DTCs) present with DTC U1153.

Ignition on.

Open circuit.

Set DTC U1153.

1. Using scan tool, attempt to establish communications with CCP.
2. Check for an open or short to power or ground on circuit No. 1807 (Purple wire).
3. Ensure CCP is connected to power and ground.
4. DTC CCP U1152 (loss of ACM serial data communications) may be present with this DTC. This indicates CCP and ACM were functional when DTC was set, but could not communicate with each other.
5. If multiple class 2 DTCs are current, check for short to ground or voltage in circuit No. 1807 (Purple wire). See the BODY CONTROL MODULE article in the ACCESSORIES/SAFETY EQUIPMENT section.

TROUBLE CODE CHART ACM DTC U1169 - LOSS OF MMM SERIAL DATA COMMUNICATIONS

DTC U1169 will set if ignition is on and ACM has lost data communication with Memory Mirror Module (MMM).

Ignition on.

Open circuit.

Set DTC U1169.

1. Using scan tool, attempt to establish communications with MMM.
2. Check for an open or short to power or ground on circuit No. 1807 (Purple wire).
3. Ensure MMM is connected to power and ground.
4. If multiple class 2 DTCs are current, check for short to ground or voltage in circuit No. 1807 (Purple wire). See the BODY CONTROL MODULE article in the ACCESSORIES/SAFETY EQUIPMENT section.

TROUBLE CODE CHART ACM DTC U1255 - GENERAL LOSS OF SERIAL DATA COMMUNICATIONS

DTC U1255 refers to a generic loss of serial data with an unknown module. DTC U1255 generally will set when vehicle is first started and ACM or CCP requests information from another module and does not get a response. DTC U1255 will clear when module communicates with ACM or CCP.

Ignition on.

Open circuit.

Set DTC U1255.

1. When DTC U1255 is set each ignition cycle even though DTC was cleared go to following steps.
2. Check for DTCs set for IPC, PZM and PCM. If IPC has set DTC U1152 or if PCM has set DTC P1605, replace ACM. If IPC, PCM or PZM has set DTC U1153, replace CCP. Ensure system is operating properly. If DTC U1152, DTC U1153 or DTC P1605 has not been set, go to next step.
3. Check option programing in IPC. Ensure that correct options have been programmed into IPC. See the BODY CONTROL MODULE article in the ACCESSORIES/SAFETY EQUIPMENT section. If IPC has been programed correctly, go to next step.
4. Ensure that correct ACM has been installed in vehicle. If correct ACM has been installed in vehicle and no problems are found in previous steps, ACM and CCP are okay. DO NOT replace components. Diagnose body communications network. See the BODY CONTROL MODULE article in the ACCESSORIES/SAFETY EQUIPMENT section.

TESTING

Note. DTCs may be viewed or cleared using self-diagnostics or scan tool. Scan tool is required to perform tests or overrides.

A/C SYSTEM PERFORMANCE

1. Park vehicle in shaded area. Ventilate interior. Vent exhaust. Install 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 engine off. Compare readings with specifications. See A/C PERFORMANCE SPECIFICATIONS table.

A/C PERFORMANCE SPECIFICATIONS

ACM SELF-DIAGNOSTICS

Note. Operating vehicle in self-diagnostic mode for extended period without engine running will drain battery, possibly causing system to give false diagnostic information. If vehicle is in self-diagnostic mode for more than 30 minutes, connect charger to battery.

Fault Detection

If ACM detects a system fault, the Vacuum Fluorescent (VF) display on the climate control panel will flash one time per second for 100 seconds. If a fault occurs in the outside temperature sensor circuit, VF display will not flash, but the outside temperature will not be displayed.

Note. ACM and Climate Control Panel (CCP) store self-diagnostic trouble codes used to identify source of any system malfunction. Diagnostic Trouble Codes (DTCs) are designed to identify malfunction as specifically as possible, including type of DTC (current or non-current history).

Note. Self-diagnostics only allows viewing and clearing of DTCs. Testing and overriding A/C system operations can only be accomplished using a scan tool.

Entering Self-Diagnostics (With Climate Control Center)

Turn ignition switch to ON position. Press OFF button and WARMER button (standard A/C-heater system), or OFF button and PASSENGER WARMER button (dual zone A/C-heater system). (Scheme 1)or (Scheme 2). Press LO fan speed (down arrow) button until ACM? is displayed. Press HI fan speed (up arrow) and ACM CODES? is displayed. Press HI fan speed (up arrow), DTCs are displayed. See DIAGNOSTIC TROUBLE CODES.

Entering Self-Diagnostics (With Scan Tool)

Connect scan tool to DLC connector located under instrument panel, on hood release bracket. Select ACM. Select DTC. Select CURRENT DTC for current DTCs or HISTORY DTC for history DTCs.

Clearing DTCs (With Climate Control Center)

Enter self-diagnostics. Press OFF button and WARMER button (standard A/C-heater system), or OFF button and PASSENGER WARMER button (dual zone A/C-heater system). Press fan LO speed (down arrow) until ACM is displayed. Press fan HI (up arrow) until ACM CODES? is displayed. Press fan LO (down arrow) until ACM CLEAR CODES? is displayed. To clear DTCs, press fan HI (up arrow) until ACM CODES CLEAR is displayed.

Clearing DTCs (With Scan Tool)

Enter self diagnostics. Select ACM. Select DTC. Select CLEAR CODES. Press YES button to clear codes.

Exiting Self-Diagnostics

Enter self-diagnostics. Press OFF and WARMER MODE or DEFOG button, or turn ignition off. DTCs are not cleared when exiting self-diagnostics.

DIAGNOSTIC TROUBLE CODES

Note. For complete information on all PCM and IPC Diagnostic Trouble Codes (DTC), see the TESTS W/CODES article in the ENGINE PERFORMANCE section.

REMOVAL & INSTALLATION

Disconnect negative battery cable. Remove right sound insulator. Remove glove box. See GLOVE BOX. Disconnect programmer electrical and vacuum connectors. Remove programmer. (Scheme 3) To install, reverse removal procedure.

Discharge A/C system, using approved refrigerant recovery/recycling equipment. Disconnect accumulator inlet and outlet refrigerant lines. Plug all lines and openings. Remove accumulator. Drain old oil from accumulator. Add same amount of oil drained plus one ounce more of NEW refrigerant oil to replacement accumulator. To install, reverse removal procedure. Evacuate and recharge A/C system.

1. Remove glove box. See «GLOVE BOX»(/cadillac/eldorado/x-1992-2002/remont/automatic-hvac-system/#hvac-system-automatic) . Unsnap rod from plastic retainer on actuator arm. Remove actuator mounting screws. Disconnect electrical connector. Remove actuator. Check air-mix door for free travel.
2. To install, reverse removal procedure. If an actuator has been replaced, actuator needs to be recalibrated for proper travel. To recalibrate actuator, cycle ignition switch to ON position for 3 minutes.

Disconnect negative battery cable. Remove instrument panel top cover. Disconnect aspirator hose. Disconnect electrical connector. Remove sensor. To install, reverse removal procedure.

Removal

1. Disconnect negative battery cable. Remove cowl cross-tower brace. Disconnect 4 ignition control module electrical connectors. Position cross car harness aside. Disconnect No. 5 and No. 7 spark plug wires. Position spark plug wires aside. Disconnect solenoid purge valve electrical and vacuum connectors.
2. Remove solenoid purge valve. Remove 3 screws and inertia plate from blower motor. Reinstall 2 screws with washers to prevent motor and housing from separating during removal. Disconnect wiring connector from blower motor. Remove 5 blower motor mounting screws. Rotate blower motor counterclockwise until flat side is down. (Scheme 39) Remove blower motor.

Installation

1. Remove inertia plate from new blower motor. Reinstall 2 screws with washers to prevent motor and housing from separating during installation. Insert blower motor with flat side down. Rotate blower motor clockwise until flat side is at 11 o'clock position. (Scheme 39)
2. Install inertia plate and screws. Install blower motor screws and tighten to 7 INCH lbs. (1 N.m). To complete installation, reverse removal procedure.

Scheme 39

1. Disconnect negative battery cable. Discharge A/C system using approved refrigerant recovery/recycling equipment. Remove serpentine drive belt. Raise and support vehicle. Remove right front wheel. Remove compressor splash shield. Remove engine splash shield and retainer.
2. Remove oil filter. Disconnect oil cooler lines from oil filter adapter. Disconnect electrical connections from compressor. Remove compressor line fitting bolt. Remove compressor from mounting bracket. Drain old oil from compressor. If less than one ounce of oil is drained from compressor, replace with 2 ounces of NEW refrigerant oil. If more than one ounce of old oil is drained from compressor, replace with same amount of NEW refrigerant oil. To install, reverse removal procedure. Evacuate and charge A/C system.

1. Disconnect negative battery cable. Discharge A/C system using approved refrigerant recovery/recycling equipment. Disable air bag system. See the AIR BAG RESTRAINT SYSTEM article in the ACCESSORIES/SAFETY EQUIPMENT section. Remove front air bag discriminating sensor mounted on radiator top support bracket, under hood latch. Remove engine front torque struts. Remove right and left cooling fans.
2. Remove radiator top support bracket. Tilt radiator/condenser assembly rearward. Disconnect pressure fittings. Cap all openings. Remove condenser-to-radiator screws. Remove condenser.
3. To install, reverse removal procedure. Add one ounce of new refrigerant oil to replacement condenser. Evacuate and charge A/C system.

1. Disconnect negative battery cable. Discharge A/C system, using approved refrigerant recovery/recycling equipment. Drain cooling system. Remove right sound insulator. Remove glove box. See «GLOVE BOX»(/cadillac/eldorado/x-1992-2002/remont/automatic-hvac-system/#hvac-system-automatic) . Disconnect vacuum and electrical connectors. Remove A/C-heater programmer. See «A/C-HEATER PROGRAMMER R & I»(/cadillac/eldorado/x-1992-2002/remont/automatic-hvac-system/#hvac-system-automatic) .
2. Loosen instrument panel brace. Remove bolt securing evaporator core housing to front of dashboard. Bolt is located above carpet, directly behind left side of console. Remove heater core. Remove cross car brace. Remove evaporator/accumulator lines.
3. Remove 2 bolts securing wiring harness pass-through to front of dashboard. Disconnect blower motor, oxygen sensor, A/C high and low pressure temperature sensors, blower motor switch, A/C low pressure switch, and ignition control module electrical connectors.
4. Remove ignition control module. Remove coolant by-pass hose from coolant recovery tank. Remove air cleaner and PCV valve. Remove left side radiator support and radiator shroud. Disconnect park/neutral position switch, MAP sensor, and cruise control servo connectors. Release wiring harness from body.
5. Disconnect brake booster hose. Remove left and right engine struts and bracket. Disconnect upper transmission cooling lines. Remove left and right cooling fans. Disconnect discharge line at condenser and suction line from accumulator. Raise and support vehicle. Remove both front wheels. Remove fuel line bracket from transmission. Remove intermediate shaft pinch bolt from steering gear. WARNING: Steering gear and/or intermediate shaft can be damaged if intermediate shaft is not disconnected from rack and pinion gear stub shaft. Loss of steering control could result if steering gear and/or intermediate shaft are damaged.
6. Remove radiator, transmission, and left wheelwell splash shields. Remove ABS unit from cradle bracket. Disconnect power steering pressure switch, vehicle speed sensor, knock sensor, and engine ground wire connectors. Remove exhaust manifold pipe at catalytic converter. Remove left and right brake calipers. Remove left and right vehicle speed sensors from body.
7. Remove 2 rear cradle-to-frame bolts. Loosen 4 remaining cradle-to-frame bolts. Lower vehicle onto cradle support stand. Remove 4 remaining cradle-to-frame bolts. Disconnect struts from strut towers. Raise vehicle off powertrain/cradle assembly.
8. Disengage electrical harness from right side valve cover. Move all loose electrical harnesses to left side of vehicle. Remove upper exhaust manifold heat shield. Remove blower motor. See «BLOWER MOTOR»(/cadillac/eldorado/x-1992-2002/remont/automatic-hvac-system/#hvac-system-automatic) . Remove evaporator core access plate and liquid line brace.
9. Remove evaporator core rubber barrier cover. Cut lower portion of case at guides. Remove evaporator core cover. Remove evaporator core.
10. To install, reverse removal procedure. Add 3 ounces of NEW refrigerant oil to replacement evaporator. Evacuate and charge A/C system.

1. Disable air bag system. See the AIR BAG RESTRAINT SYSTEM article in the ACCESSORIES/SAFETY EQUIPMENT section. Open trap door in rear of glove box. Disconnect passenger-side air bag module wiring connector from retaining clip on rear of glove box. Remove glove box light lens by gently prying release tabs. Gently pry top of switch cover to release tab.
2. Reaching through light opening, push switch outboard. Disconnect electrical connector, and remove switch. Remove 6 glove box-to-instrument panel screws. Remove glove box. To install, reverse removal procedure.

1. Disconnect negative battery cable. Partially drain coolant. Remove glove box. See «GLOVE BOX»(/cadillac/eldorado/x-1992-2002/remont/automatic-hvac-system/#hvac-system-automatic) . Remove right lower sound insulator. Disconnect electrical connectors. Remove A/C-heater programmer. See «A/C-HEATER PROGRAMMER R & I»(/cadillac/eldorado/x-1992-2002/remont/automatic-hvac-system/#hvac-system-automatic) .
2. Remove heater core cover. Remove inlet and outlet hoses from heater core. Remove 2 heater core retaining screws. Remove heater core. To install, reverse removal procedure. Fill cooling system. Perform air-mix valve adjustment. See AIR-MIX VALVE under «ADJUSTMENTS»(/cadillac/eldorado/x-1992-2002/remont/automatic-hvac-system/#hvac-system-automatic) .

HIGH PRESSURE SWITCH

Note. High pressure switch is mounted on Schrader valve; system does not need to be discharged.

Disconnect negative battery cable. Disconnect high pressure switch connector, located in compressor discharge line between compressor and condenser. Unscrew switch from refrigerant line. To install, reverse removal procedure.

LOW PRESSURE SWITCH

Note. Low pressure switch is mounted on Schrader valve; system does not need to be discharged.

Disconnect negative battery cable. Disconnect low pressure switch electrical connector, located at rear of engine compartment above evaporator case. Unscrew switch from refrigerant line. To install, reverse removal procedure.

Remove radiator core plastic cover. Disconnect outside temperature sensor connector. Remove sensor. To install, reverse removal procedure.

1. Locate temperature sensors either on high-side or low-side refrigerant line just above evaporator case in engine compartment.
2. Discharge A/C system, using approved refrigerant recovery/recycling equipment. Disconnect sensor connector. Unscrew switch from refrigerant line. To install, reverse removal procedure.

Remove windshield center defogger grille. Remove sunload sensor screws. Remove sunload sensor. To install, reverse removal procedure.

Turn front wheels to right. Raise and support vehicle. Remove mounting screws and vacuum hose from tank. Remove vacuum tank. To install, reverse removal procedure.

TORQUE SPECIFICATIONS

TORQUE SPECIFICATIONS

Scheme 40

Scheme 41

Automatic A/C-Heater System Wiring Diagram (1 Of 2). Scheme 42

Automatic A/C-Heater System Wiring Diagram (2 Of 2). Scheme 43

See also:
• ACM SELF-DIAGNOSTICS
• TEMPERATURE & MODE SETTINGS
• TESTING