HVAC System Cadillac DeVille Concours I final

SPECIFICATIONS

SPECIFICATIONS

DESCRIPTION

Note. The 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 Climate Control Panel (CCP) 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.

Scheme 1

Scheme 2

BLOWER 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.

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.

DeVille Concours & Eldorado

Rear blower control panel, 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. (Scheme 3)

Scheme 3

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 (CCP) display.

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

OFF Mode

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

Because blower 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

When AUTO mode is 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 mode, 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 mode, everything is controlled automatically. Most of air is delivered to windshield.

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

In this mode, 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 temperature settings. Passenger temperature control can be adjusted at the control panel or from passenger armrest temperature control panel (if equipped).

When system is operating in any mode except dual zone mode, actuators operate in unison. When operating in dual zone mode, passenger may adjust outlet temperature. Temperature may be adjusted 4 degrees, plus or minus, from set temperature.

RECIRC Mode

In this mode, 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 switch is cycled off.

AIR DELIVERY SYSTEM

The Heating, Ventilation, and Air Conditioning (HVAC) module incorporates most of the air conditioning components into one assembly. The function of the HVAC module is to distribute conditioned air 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 4) Eldorado and DeVille Concours may have an auxiliary blower in the rear of the center console (if equipped), allowing rear seat occupants to control air velocity. (Scheme 3)

Scheme 4

A/C-HEATER PROGRAMMER

Note. The A/C-heater programmer may also be referred as Air Conditioning Module (ACM).

A/C-Heater Programmer (ACM) is located behind the glove box, attached to bracket next to right end of HVAC module assembly. 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 A/C-HEATER PROGRAMMER (ACM) SELF-DIAGNOSTICS under SELF-DIAGNOSTICS.

COOLING FANS

The Powertrain Control Module (PCM) commands low speed cooling fan operation by grounding cooling fan relay No. 1. When commanded, a series circuit through both cooling 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 circuit to ground 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 cooling fan operation, provides a ground path for left cooling fan motor. When minimum cooling is needed, PCM energizes cooling fan relay No. 1. When maximum cooling is needed, PCM energizes all 3 relays. Left cooling fan motor runs at high speed and is powered through cooling fan relay No. 1, and grounded through cooling fan relay No. 2. Right cooling fan motor is powered through cooling fan relay No. 3 and runs at high speed.

Low speed cooling fan operation will occur when

1. A/C operation is requested.
2. Engine coolant temperature is less than 229°F (109°C).
3. Transmission fluid temperature is less than 302°F (150°C).
4. When ignition switch is turned to OFF position, if engine coolant temperature is greater than 304°F (151°C) and battery voltage is greater than 12 volts, cooling fans 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 greater.
2. Transmission fluid temperature is greater than 304°F (151°C). When engine coolant temperature is cooled to less than 229°F (109°C), cooling fans will switch from high speed to low speed operation.

In-Vehicle Temperature Sensor

This sensor is located at the left center of instrument panel. 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. Sensor 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.

Sun Load Sensor

The sun load sensor is located under 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; highest when shaded. ACM processes this signal together with temperature signals to determine the cooling necessary for maintaining selected interior temperature.

HIGH-PRESSURE RELIEF VALVE

This valve is located on rear of A/C compressor. Valve opens and vents refrigerant to atmosphere when pressure in system exceeds 525 psi (37 kg/cm 2 ).

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 compressor clutch. When pressure drops to 200 psi (14.1 kg/cm 2 ), switch will close and allow compressor clutch 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.

LOW REFRIGERANT MESSAGE

If refrigerant system state of charge falls to less than one fourth of capacity, VERY LOW REFRIGERANT - COMPRESSOR OFF message will be displayed on Drivers Information Center (DIC). DTC B1347 and/or B1348 will be stored in ACM.

PROGRAM NUMBER

The program number is calculated by the A/C-Heater Programmer (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 sun load 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

A/C-Heater Programmer (ACM) determines appropriate air mix valve position by monitoring set temperature, outside air temperature, in-vehicle air temperature, low-side temperature, sun load 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.

AIR DELIVERY MODE CONTROL

A/C-Heater Programmer (ACM) will direct blended air in one of several air delivery modes, based on current program number and climate control settings. See CLIMATE CONTROL PANEL 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 (floor) 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 mode, 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 of 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 velocity until coolant temperature has increased to prevent fogging of windshield. See PURGE MODE . Selecting blower HI setting will override ACM control allowing full blower operation.

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, HVAC is off, or 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), engine is running, HVAC is on, diagnostics has been 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, depending upon current conditions. Purge modes are intended to improve comfort and reduce windshield fogging after initial start-up. 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 to ensure proper valve travel. Cycle ignition switch to ON position for 3 minutes to allow programmer and actuator(s) to recalibrate travel. For driver or passenger link rod adjustment, see appropriate link rod adjustment procedure.

Driver Link Rod Adjustment

1. Remove right sound insulator. Remove glove box. See «GLOVE BOX»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-hvac-system/#hvac-system) under REMOVAL & INSTALLATION. Start engine, 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 5) 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/deville-concours/i-final-1999-1999/remont/automatic-hvac-system/#hvac-system) under REMOVAL & INSTALLATION. Pull link rod from retainer on programmer output arm. (Scheme 5) Start engine, 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 5)

Scheme 5

SET TEMPERATURE OFFSET

Displayed set temperature can be varied from actual (commanded) output temperature a maximum of 5°F (-15°C). This feature allows warm up or cool down of the HVAC system's set temperature for optimum efficiency and temperature control. To adjust set temperature offset, enter diagnostics through climate control panel. See A/C-HEATER PROGRAMMER (ACM) SELF-DIAGNOSTICS under SELF-DIAGNOSTICS. Display Instrument Panel Cluster (IPC) override output. Press cooler or warmer button to adjust desired set temperature. Hold ECON and DEF buttons down for 3 seconds to overwrite new value in memory.

TROUBLE SHOOTING

Note. Body Control Module (BCM) may be referred as Platform Zone Module (PZM). A/C-heater Programmer may be referred to as Air Conditioning Module (ACM). Ambient temperature must be greater than 42°F (5°C) before beginning functional tests.

Without Dual Zone Climate Controls

1. Start engine and bring to operating temperature. Press OFF button. (Scheme 1) Blower will stop running, display will show set temperature, and OFF indicator will be illuminated on display. Outside temperature will be displayed after short time.
2. Press AUTO button. System will turn on. Display will show AUTO fan and AUTO mode. Set temperature to 60°F (15°C). Set temperature will be indicated, blower motor will operate at high speed, and cold air will flow from instrument panel outlets.
3. Press ECON button. RECIRC LED will turn off, and ECON will be displayed.
4. Press RECIRC button. RECIRC LED will turn on and blower motor noise will increase slightly.
5. Press AUTO button. AUTO will be displayed.
6. Set temperature to 90°F (32°C). RECIRC LED will turn off, and warm air will flow from heater (floor) outlets.
7. Press DEFOG button (if equipped). RECIRC LED will be on and blower noise will increase slightly.
8. Press RECIRC button. RECIRC LED will turn on and blower motor noise will increase slightly.
9. Press defrost button. Air will flow from windshield outlets and RECIRC LED will be off.
10. Press fan button down twice. Blower will operate at low speed and LOW will be displayed.

With Dual Zone Climate Controls

1. Start engine and bring to operating temperature. Press OFF button. (Scheme 2) Blower will stop running, display will show set temperature, and OFF indicator will be illuminated on display. Outside temperature will be displayed after short time.
2. Press AUTO button. System will turn on. Display will show fan icon, mode arrows, set temperature, and AUTO will be displayed. Set temperature to 60°F (15°C). Set temperature will be indicated, blower motor will operate at high speed, recirculation LED will be on, and cold air will flow from instrument panel outlets.
3. Press fan button down twice. Blower motor will operate at low speed.
4. Press AUTO button. Blower motor will run at high speed.
5. Press MODE button up once. Air will flow from heater (floor) and windshield outlets.
6. Press MODE button down once. Air will flow from instrument panel outlets.
7. Press MODE button down once. Air will flow from instrument panel and heater outlets.
8. Press MODE button down once. Air will flow from heater outlets.
9. Press recirculation button (located below A/C button). Recirculation LED will be illuminated and blower motor noise will increase slightly.
10. Press defrost button (located to left of fan button). Air will flow from windshield outlets and blower will operate at high speed.
11. Set temperature to 90°F (32°C). Hot air will flow from windshield outlets.
12. Set temperature to 75°F (24°C) and press AUTO button. AUTO will be displayed.
13. Press PASS TEMP button up 4 times. Air from passenger side of instrument panel outlets should be warmer than driver side outlets. Display should show 3 1/2 Red bar segments on passenger side for blower motor speed.

NO BLOWER OPERATION/IMPROPER BLOWER SPEED

1. Start engine and connect scan tool. Set blower motor to high speed (99 percent indicated on scan tool). Display function test for blower motor on scan tool. Change blower motor speed from high to low. If blower motor counts on scan tool steadily decreases from 99 to approximately 30 percent and hold steady, go to next step. If blower motor speed is steady, then off, go to step 3 . If blower motor does not operate or is intermittent, go to step 5 .
2. Blower motor operating as designed. Check for malfunctioning temperature control.
3. Turn ignition switch to OFF position. Exit diagnostics on scan tool and start engine. Select LO blower motor speed. Using a DVOM, check voltage between ground and blower motor connector terminal "B" (Gray wire). If reading is less than 9 volts, go to step 12 . If reading is 9 volts or more, go to next step.
4. With a DVOM still connected, set blower motor to HI speed position. If reading changes to 4 volts or less, go to step 13 . If reading does not change to 4 volts or less, go to step 12 .
5. Use scan tool to view blower motor speed in percent. Command blower to HI speed with scan tool (100 percent). Command blower motor to LO speed with scan tool (42 percent). If commanded value is equal to actual value, go to step 8 . If commanded value does not equal actual value, go to next step.
6. Use scan tool to view blower motor speed in percent. Set climate control panel to AUTO and temperature control to 75°F (24°C). Increase or decrease set temperature on climate control panel. If blower speed is 40-100 percent, go to step 8 . If blower speed is not 40-100 percent, go to next step.
7. Replace A/C-heater programmer (ACM). Recheck blower motor operation.
8. Using a DVOM, measure voltage between ground and blower motor connector terminal "B" (Gray wire). If reading is greater than 4 volts, go to next step. If reading is not greater than 4 volts, go to step 12 .
9. Disconnected blower motor connector. Using a DVOM, measure resistance between battery voltage and blower motor connector terminal "C" (Red wire). Next, measure resistance between ground and blower motor connector terminal "A" (Black wire). If resistance is greater than one ohm, go to next step. If resistance is less than one ohm, go to step 11 .
10. Check INDVERT (50-amp) fuse for open. Repair open in Red wire between fuse block and blower motor connector terminal "C", or open in Black wire between blower motor connector terminal "A" and ground. Recheck blower motor operation.
11. Turn ignition switch to OFF position. Using a DVOM, measure resistance between ground and blower motor connector terminal "B" (Gray wire). If resistance is less than 250 k/ohms, go to next step. If resistance is greater than 250 k/ohms, go to step 13 .
12. Repair short to voltage in Gray wire between blower motor connector terminal "B" and ACM connector terminal D3. If circuit is okay, replace A/C-heater programmer (ACM). Recheck blower motor operation.
13. Replace blower motor. Recheck blower motor operation.

BLOWER MOTOR ON ALL THE TIME

1. Turn ignition switch to OFF position. Using a DVOM, measure voltage between ground and blower motor connector terminal "B" (Gray wire). If battery voltage is indicated, go to next step. If less than battery voltage is indicated, go to step 6 .
2. Disconnect blower motor connector. Using a DVOM, measure resistance between battery voltage and blower motor connector terminal "C" (Red wire). Next, measure resistance between ground and blower motor connector terminal "A" (Black wire). If resistance is greater than one ohm, go to next step. If resistance is less than one ohm, go to step 4 .
3. Check INDVERT (50-amp) fuse for open. Repair open in Red wire between fuse block and blower motor connector terminal "C", or open in Black wire between blower motor connector terminal "A" and ground. Recheck blower motor operation.
4. Turn ignition switch to OFF position. Using a DVOM, measure resistance between ground and blower motor connector terminal "B" (Gray wire). If resistance is less than 250 k/ohms, go to next step. If resistance is greater than 250 k/ohms, go to step 6 .
5. Repair short to voltage in Gray wire between blower motor connector terminal "B" and ACM connector terminal D3. If circuit is okay, replace ACM. Recheck blower motor operation.
6. Replace blower motor. Recheck blower motor operation.

IMPROPER AIR DELIVERY

1. Start engine, bring to operating temperature. Set blower motor to high speed. Connect scan tool. Command recirculation door to open and close with scan tool. If recirculation door operates, go to step 6 . If recirculation door does not operate, go to next step.
2. Remove programmer vacuum hose connector. Measure vacuum at Orange hose in connector. If 10 in. Hg or more of vacuum is indicated, go to step 4 . If less than 10 in. Hg vacuum is indicated, go to next step.
3. Repair vacuum source. Recheck operation of air delivery system.
4. Use hand-held vacuum pump to apply vacuum to Orange hose. If Orange hose holds vacuum, go to next step. If Orange hose does not hold vacuum, go to step 12 .
5. Check for stuck inlet valve, door, or actuator. Check for proper hose routing. If okay, replace A/C-heater programmer (ACM). Recheck operation of air delivery system.
6. Using scan tool, select AIR DOWN. If air distribution is from heater (floor) outlets with small amount from windshield and instrument panel outlets, go to step 9 . If air distribution is not as specified, go to next step.
7. Remove programmer vacuum hose connector. Use hand-held vacuum pump to apply vacuum to Yellow hose. If Yellow hose holds vacuum, go to next step. If Yellow hose does not hold vacuum, go to step 12 .
8. Check for stuck up/down valve, door, or actuator. Check for proper hose routing. If okay, replace ACM. Recheck operation of air delivery system.
9. Use scan tool to select A/C DEFROST. If air distribution is from instrument panel and windshield outlets, with small amount from heater outlets, go to step 13 . If air distribution is not as specified, go to next step.
10. Use hand-held vacuum pump to apply vacuum to Red hose. If Red hose holds vacuum, go to next step. If Red hose does not hold vacuum, go to step 12 .
11. Check for stuck up/down valve, door, or actuator. Check for proper hose routing. If okay, replace ACM. Recheck operation of air delivery system.
12. Repair leaking hose or repair/replace leaking actuator. Recheck operation of air delivery system.
13. If air delivery is from instrument panel vents, go to step 15 . If air delivery is not from instrument panel vents, go to next step.
14. Check for stuck A/C defrost valve, door, or actuator. Check for proper hose routing. If okay, replace ACM. Recheck operation of air delivery system.
15. Use scan tool to select AIR UP. If air delivery is from instrument panel outlets with a small amount of delivery from windshield outlets, go to step 17 . If other than specified, go to next step.
16. Check for stuck A/C defrost valve, door, or actuator. Check for proper hose routing. Repair leaking hose or repair/replace leaking actuator. Recheck operation of air delivery system.
17. System operating as designed.

TEMPERATURE SETTING DOES NOT PROVIDE COMFORT

Visually check inside temperature sensor aspirator. Make sure aspirator is drawing passenger compartment air into temperature sensor housing opening. If air is not being drawn into housing, ensure that aspirator hose is connected properly and not kinked or bent. Ensure that sensor opening is not restricted. Check that air mix valve is operating properly and not binding. If all are okay, replace the aspirator.

PASSENGER TEMPERATURE OFFSET DOES NOT FUNCTION PROPERLY

1. Perform appropriate «FUNCTIONAL TEST»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-hvac-system/#hvac-system) . Go to next step.
2. Ambient temperature must be greater than 48°F (8°C) before self-diagnostics can be performed. Start engine, bring to operating temperature. Set climate control panel to 85°F (29°C). Set PASS TEMP on climate control panel to coolest setting. If air from passenger instrument panel outlets is cooler than driver's instrument panel outlets, go to next step. If passenger side is not cooler than driver side, go to step 5 .
3. Set climate control panel to 65°F (18°C). Set PASS TEMP on climate control panel to warmest setting. If air from passenger instrument panel outlets is warmer than driver's instrument panel outlets, go to next step. If passenger side is not warmer than driver side, go to step 5 .
4. System operating as designed. Inform customer of system operation.
5. Check for proper door actuator adjustment. Check for broken linkage or missing components. Connect scan tool. Reprogram dual zone ON. Recheck system for proper operation. If passenger temperature control does not operate, see «DUAL ZONE SWITCH DIAGNOSIS»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-hvac-system/#hvac-system__dual-zone-switch-diagnosis) .

DUAL ZONE SWITCH DIAGNOSIS

Note. This test is for vehicles equipped with passenger temperature control panel located in passenger door.

1. Turn ignition switch to ON position. Set passenger temperature control panel to warmest position. Using a DVOM, backprobe and measure voltage between ground and A/C-heater programmer (ACM) connector terminal D13 (Dark Blue/White wire). If reading is 12 volts, go to next step. If reading is not 12 volts, go to step 8 .
2. Set passenger temperature control panel to coldest position. Using a DVOM, backprobe to measure voltage between ground and ACM connector terminal D13 (Dark Blue/White wire). If reading is zero volts, go to next step. If reading is not zero volts, go to step 8 .
3. Press and hold passenger temperature control button down. Using a DVOM, backprobe and measure voltage between ground and ACM connector terminal C16 (Dark Blue wire). If reading is zero volts, go to next step. If reading is not zero volts, go to step 9 .
4. Release passenger temperature control button. Using a DVOM, backprobe and measure voltage between ground and ACM connector terminal C16 (Dark Blue wire). If reading is 12 volts, go to next step. If reading is not 12 volts, go to step 9 .
5. Turn passenger temperature control off. Using a DVOM, backprobe and measure voltage between ground and ACM connector terminal D10 (Purple wire). If reading is 12 volts, go to next step. If reading is not 12 volts, go to step 10 .
6. Turn passenger temperature control on. Using a DVOM, backprobe and measure voltage between ground and ACM connector terminal D10 (Purple Blue wire). If reading is less then 12 volts, go to next step. If reading is 12 volts or greater, go to step 10 .
7. Check ACM connector terminal contact. If okay, replace ACM. Recheck dual zone mode operation.
8. Check for open or short in Dark Blue/White wire between ACM connector terminal D13 and passenger temperature control connector terminal No. 6. If circuit is okay, replace passenger temperature control panel. Recheck dual zone mode operation.
9. Check for open or short in Dark Blue wire between ACM connector terminal C16 and passenger temperature control connector terminal No. 8. If circuit is okay, replace passenger temperature control panel. Recheck dual zone mode operation.
10. Check for open or short in Purple wire between ACM connector terminal D10 and passenger temperature control connector terminal No. 5. If circuit is okay, replace passenger temperature control panel. Recheck dual zone mode operation.

REAR BLOWER SPEED INCORRECT

1. Turn ignition switch to ON position. Connect scan tool and select REAR BLOWER. Adjust speed on Climate Control Panel (CCP) and monitor scan tool display. If high and low speed are okay and all other speeds are incorrect, go to step 6 . If all speeds are incorrect, go to step 3 . If only high speed is incorrect, go to next step.
2. Repair Orange wire between splice and rear blower control connector terminal "B". See WIRING DIAGRAMS. Recheck operation of rear blower motor.
3. If all speeds are high, go to step 5 . If all speeds are indicated low, go to next step.
4. Check Orange and Brown wire for open or short. Recheck operation of rear blower motor.
5. Check Black wire before rear blower control for good ground. Recheck operation of rear blower motor.
6. Using a DVOM, measure voltage between ground and rear blower resistor module connector terminal "C". Set rear blower control to low position. If reading is between 1.8 and 2.3 volts, go to step 8 . If reading is not between 1.8 and 2.3 volts, go to next step.
7. Check Orange wire between splice and rear blower resistor module connector terminal "C". If circuit is okay, replace rear blower resistor module. Recheck operation of rear blower motor.
8. Using a test light connected to ground, backprobe blower resistor connector terminals "A", "B", and "D". If test light illuminates for terminal "A", go to step 11 . If test light illuminates for terminal "B", go to step 10 . If test light illuminates for terminal "D", go to step 12 .
9. Recheck operation of rear blower motor.
10. Check for open or short in Purple wire between rear blower control connector terminal "C" and rear blower resistor module connector terminal "B". If circuit is okay, replace rear blower control. Recheck operation of rear blower motor.
11. Check for open or short in Light Blue wire between rear blower control connector terminal "A" and rear blower resistor module connector terminal "D". If circuit is okay, replace rear blower control. Recheck operation of rear blower motor.
12. Check for open or short in Tan wire between rear blower control connector terminal "D" and rear blower resistor module connector terminal "E". If circuit is okay, replace rear blower control. Recheck operation of rear blower motor.

REAR BLOWER MOTOR INOPERATIVE

1. Turn ignition switch to ON position. If blower motor will not operate in any setting, go to step 5 . If blower motor will operate in one or more settings, go to next step.
2. Remove center console rear cover. Disconnect rear blower control connector. Using a fused jumper wire, connect terminals "B", "C", "D", and "E" to ground one at a time. If blower motor runs at correct speeds, go to step 4 . If blower motor does not run at correct speeds, go to next step.
3. Check connector terminals at blower resistor module. Check wiring between rear blower control and rear blower resistor module for continuity. If connectors and circuits are okay, replace blower resistor module. Recheck operation of rear blower motor.
4. Check connector terminals at rear blower control. If connector is okay, replace rear blower control. Recheck operation of rear blower motor.
5. Set rear blower control to HI position. Using a DVOM, measure voltage between ground and blower motor connector terminal "A" (Black wire). If battery voltage is indicated, go to step 7 . If battery voltage is not indicated, go to next step.
6. Check CONSOLE (10-amp) fuse for open. If fuse is open, check for short to ground in Brown wire after fuse block. Using an ammeter, verify blower motor current draw at less than 6 amps. If fuse is okay, check for open in Brown wire between fuse block and rear blower motor.
7. Remove center console rear cover. Disconnect rear blower control connector. Using a DVOM, measure resistance between ground and connector terminal "A" (Black wire). If reading is less than one ohm, go to step 9 . If reading is greater than one ohm, go to next step.
8. Repair open in Black wire between rear blower control connector terminal "A" and ground. Recheck operation of rear blower motor.
9. Connect test light between blower motor control connector terminals "A" (Black wire) and "B" (Orange wire). If test light comes on, go to step 11 . If test light does not come on, go to next step.
10. Repair open in Orange wire between splice and rear blower control connector terminal "B". Recheck operation of rear blower motor.
11. Turn ignition switch to OFF position. Test light should go off when ignition switch is turned off. If test light does not go off, repair short to voltage in Orange wire. If circuit is okay, replace rear blower control. Recheck operation of rear blower motor.

Note. Check for, and repair any A/C-related DTCs before proceeding with COOLING FAN FUNCTIONAL CHECK . If DTC P1660 is set, or sets during cooling fan functional check, DTC P1660 must be diagnosed before proceeding.

Cooling Fan Functional Check

1. If On-Board Diagnostic (OBD) System Check has not been performed, see appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE. If OBD system check has been performed, go to next step.
2. Ensure engine coolant temperature is 41-212°F (5-100°C). Switch A/C controls to OFF position. Start engine and let idle. Using scan tool, select OUTPUT TESTS. While viewing QUAD DRIVER 1 display, command ALL RELAYS OFF for about 15 seconds, then ALL RELAYS ON for about 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 appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE.
3. With engine idling, turn A/C controls to ON position for 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, see «A/C-HEATER PROGRAMMER (ACM) SELF-DIAGNOSTICS»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-hvac-system/#hvac-system__ac-heater-programmer-acm-self-diagnostics) under SELF-DIAGNOSTICS.
4. Turn ignition switch to ON position. Ensure engine coolant temperature is less than 212°F (100°C). Using scan tool, command FAN RELAY NO. 1 ON, then ALL FAN RELAYS ON, then ALL FAN RELAYS OFF while monitoring cooling fan operation. When cooling fan relay No. 1 is on, both cooling fans should run at low speed. When all cooling fan relays are commanded on, both cooling fans should run at high speed. When all cooling fan relays are commanded off, both cooling fans should not run (unless PCM detects a fault or there is a high temperature condition). If cooling fans do not run as specified, go to next step. If cooling fans run as specified, system is operating properly.
5. If only left cooling fan runs when cooling fan relay No. 1 is commanded on, and both cooling fans run when all cooling fan relays are commanded on, go to next step. If cooling fans do not run as specified, go to step 7 .
6. Repair White wire for a short to ground between left cooling fan motor and cooling fan relay No. 2. Go to step 4 .
7. If neither cooling fan runs when cooling fan relay No. 1 is commanded on and only right cooling fan runs when all cooling fan relays are commanded on, go to «COOLING FAN SYMPTOM CHECK NO. 1»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-hvac-system/#hvac-system__cooling-fan-symptom-check-no-1) . If cooling fans do not run as specified, go to next step.
8. If neither cooling fan runs when cooling fan relay No. 1 is commanded on and only left cooling fan runs when all cooling fan relays are commanded on, go to «COOLING FAN SYMPTOM CHECK NO. 2»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-hvac-system/#hvac-system__cooling-fan-symptom-check-no-2) . If cooling fans do not run as specified, go to next step.
9. If both cooling fans run when cooling fan relay No. 1 is commanded on and only right cooling fan runs when all cooling fan relays are commanded on, go to «COOLING FAN SYMPTOM CHECK NO. 3»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-hvac-system/#hvac-system__cooling-fan-symptom-check-no-3) . If cooling fans do not run as specified, go to next step.
10. If both cooling fans run when cooling fan relay No. 1 is commanded on and only left cooling fan runs when all cooling fan relays are commanded on, go to «COOLING FAN SYMPTOM CHECK NO. 4»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-hvac-system/#hvac-system__cooling-fan-symptom-check-no-4) . If cooling fans do not run as specified, go to next step.
11. If neither cooling fan runs when cooling fan relay No. 1 is commanded on and neither cooling fan runs when all cooling fan relays are commanded on, go to «COOLING FAN SYMPTOM CHECK NO. 5»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-hvac-system/#hvac-system__cooling-fan-symptom-check-no-5) . If cooling fans do not run as specified, go to next step.
12. If either cooling fan runs when all cooling fan relays are 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»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-hvac-system/#hvac-system__cooling-fan-functional-check) when repair is completed to ensure system is operating properly. If cooling fans do not run as specified, repeat step 4 .

Cooling Fan Symptom Check No. 1

1. Perform cooling fan functional check, before proceeding. If cooling fan functional check has been performed, go to next step. If check has not been performed, go to «COOLING FAN FUNCTIONAL CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-hvac-system/#hvac-system__cooling-fan-functional-check) .
2. Disconnect left cooling fan motor harness connector. Using scan tool, select OUTPUT TESTS, then FAN RELAYS. Turn ignition switch to ON position. Command FAN RELAY NO. 1 ON. Using a DVOM, measure voltage between ground and Black wire at left cooling fan motor harness connector. If reading is 10 volts or greater, go to next step. If reading is less than 10 volts, go to step 6 .
3. Connect a fused jumper wire between terminal "A" (White wire) and terminal "B" (Black wire) at left cooling fan motor harness connector. If right cooling fan runs, go to step 8 . If right cooling fan does not run, go to next step.
4. With jumper wire still connected, remove cooling fan relay No. 2. Using a DVOM, measure voltage between ground and White wire at cooling fan relay No. 2 connector. If reading is 10 volts or greater, go to next step. If reading is less than 10 volts, go to step 9 .
5. Connect an additional fused jumper wire between White wire and Light Blue wire at cooling fan relay No. 2 connector. With both jumper wires connected, if right cooling fan runs, go to step 10 . If right cooling fan does not run, go to step 11 .
6. Using scan tool, exit FAN RELAYS. Remove cooling fan relay No. 1. Using a DVOM, measure voltage between ground and Red wire at cooling fan relay No. 1 connector. If reading is 10 volts or greater, go to next step. If reading is less than 10 volts, go to step 12 .
7. Connect a fused jumper wire between Red wire and Black wire at cooling fan relay No. 1 connector. Using a DVOM, measure voltage between ground and Black wire at left cooling fan motor harness connector. If reading is 10 volts or greater, go to step 13 . If reading is less than 10 volts, go to step 14 .
8. Replace left cooling fan motor. Go to «COOLING FAN FUNCTIONAL CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-hvac-system/#hvac-system__cooling-fan-functional-check) .
9. Repair open in White wire between left cooling fan motor and cooling fan relay No. 2.
10. Replace cooling fan relay No. 2. Go to «COOLING FAN FUNCTIONAL CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-hvac-system/#hvac-system__cooling-fan-functional-check) .
11. Repair open in Light Blue wire between cooling fan relay No. 2 and circuit splice between cooling fan relay No. 3 and right cooling fan motor. Go to «COOLING FAN FUNCTIONAL CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-hvac-system/#hvac-system__cooling-fan-functional-check) .
12. Repair open in Red wire between COOL FNS (50-amp) fuse and cooling fan relay No. 1. Go to «COOLING FAN FUNCTIONAL CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-hvac-system/#hvac-system__cooling-fan-functional-check) .
13. Replace cooling fan relay No. 1. Go to «COOLING FAN FUNCTIONAL CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-hvac-system/#hvac-system__cooling-fan-functional-check) .
14. Repair open in Black wire between cooling fan relay No. 1 and left cooling fan motor. Go to «COOLING FAN FUNCTIONAL CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-hvac-system/#hvac-system__cooling-fan-functional-check) .

Cooling Fan Symptom Check No. 2

1. Perform cooling fan functional check, before proceeding. If cooling fan functional check has been performed, go to next step. If check has not been performed, go to «COOLING FAN FUNCTIONAL CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-hvac-system/#hvac-system__cooling-fan-functional-check) .
2. Disconnect right cooling fan motor harness connector. Using scan tool, select OUTPUT TESTS, then FAN RELAYS. Turn ignition switch to ON position. Command FAN RELAY NO. 1 ON. Connect a fused jumper wire between terminal "A" (Black wire) and terminal "B" (Light Blue wire) at right cooling fan motor harness connector. If left cooling fan runs, go to step 5 . If left cooling fan does not run, go to next step.
3. With cooling fan relay No. 1 still commanded on, remove cooling fan relay No. 2. Connect a fused jumper wire between White wire and Light Blue wire at cooling fan relay No. 2 connector. If left cooling fan runs, go to step 6 . If left cooling fan does not run, go to next step.
4. With cooling fan relay No. 2 jumper wire still connected, measure voltage between ground and Light Blue wire at right cooling fan motor harness connector. If reading is 10 volts or greater, go to step 7 . If reading is less than 10 volts, go to step 8 .
5. Replace right cooling fan motor. Go to «COOLING FAN FUNCTIONAL CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-hvac-system/#hvac-system__cooling-fan-functional-check) .
6. Replace cooling fan relay No. 2. Go to «COOLING FAN FUNCTIONAL CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-hvac-system/#hvac-system__cooling-fan-functional-check) .
7. Repair open in Black wire between right cooling fan motor and circuit splice between cooling fan relay No. 2 and ground. Go to «COOLING FAN FUNCTIONAL CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-hvac-system/#hvac-system__cooling-fan-functional-check) .
8. Repair open in Light Blue wire between right cooling fan motor and circuit splice between cooling fan relay No. 2 and cooling fan relay No. 3. Go to «COOLING FAN FUNCTIONAL CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-hvac-system/#hvac-system__cooling-fan-functional-check) .

Cooling Fan Symptom Check No. 3

1. Perform cooling fan functional check, before proceeding. If cooling fan functional check has been performed, go to next step. If check has not been performed, go to «COOLING FAN FUNCTIONAL CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-hvac-system/#hvac-system__cooling-fan-functional-check) .
2. Using scan tool, select OUTPUT TESTS, then FAN RELAYS. Turn ignition switch to ON position. Command ALL FAN RELAYS ON. Remove cooling fan relay No. 2. Using a DVOM, measure voltage between ground and Orange wire at cooling fan relay No. 2 connector. If reading is 10 volts or greater, go to next step. If reading is less than 10 volts, go to step 5 .
3. Remove cooling fan relay No. 3. Measure resistance of Dark Blue wire between cooling fan relay No. 2 and cooling fan relay No. 3. If resistance is 5 ohms or less, go to next step. If resistance is greater than 5 ohms, go to step 6 .
4. Reconnect cooling fan relay No. 3. With all relays still commanded ON, connect a fused jumper wire between White wire and Black wire at cooling fan relay No. 2 connector. If both cooling fans run, go to step 8 . If both cooling fans do not run, go to step 7 .
5. Repair open in Orange wire between cooling fan relay No. 2 and circuit splice between A/C compressor relay and cooling fan relays No. 1 and 3. Go to «COOLING FAN FUNCTIONAL CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-hvac-system/#hvac-system__cooling-fan-functional-check) .
6. Repair open in Dark Blue wire between cooling fan relay No. 2 and circuit splice between PCM harness connector terminal No. 33 and cooling fan relay No. 3. Go to «COOLING FAN FUNCTIONAL CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-hvac-system/#hvac-system__cooling-fan-functional-check) .
7. Repair open in Black wire between cooling fan relay No. 2 and circuit splice between right cooling fan motor and ground. Go to «COOLING FAN FUNCTIONAL CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-hvac-system/#hvac-system__cooling-fan-functional-check) .
8. Replace cooling fan relay No. 2. Go to «COOLING FAN FUNCTIONAL CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-hvac-system/#hvac-system__cooling-fan-functional-check) .

Cooling Fan Symptom Check No. 4

1. Perform cooling fan functional check, before proceeding. If cooling fan functional check has been performed, go to next step. If check has not been performed, go to «COOLING FAN FUNCTIONAL CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-hvac-system/#hvac-system__cooling-fan-functional-check) .
2. Using scan tool, select OUTPUT TESTS, then FAN RELAYS. Turn ignition switch to ON position. Command ALL FAN RELAYS ON. Remove cooling fan relay No. 3. Using a DVOM, measure voltage between ground and Orange wire at cooling fan relay No. 3 connector. If reading is 10 volts or greater, go to next step. If reading is less than 10 volts, go to step 6 .
3. Using a DVOM, measure voltage between ground and Red wire at cooling fan relay No. 3 connector. If reading is 10 volts or greater, go to next step. If reading is less than 10 volts, go to step 7 .
4. Remove cooling fan relay No. 3. Using a DVOM, measure resistance of Dark Blue wire between cooling fan relay No. 2 and cooling fan relay No. 3. If resistance is 5 ohms or less, go to next step. If resistance is greater than 5 ohms, go to step 8 .
5. Reconnect cooling fan relay No. 2. Using scan tool, command ALL FAN RELAYS ON. Connect a fused jumper wire between Red wire and Light Blue wire at cooling fan relay No. 3 connector. If right cooling fan runs, go to step 10 . If right cooling fan does not run, go to step 9 .
6. Repair open in Red wire between COOL FNS (50-amp) fuse and cooling fan relay No. 3. Go to «COOLING FAN FUNCTIONAL CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-hvac-system/#hvac-system__cooling-fan-functional-check) .
7. Repair open in Orange wire between cooling fan relay No. 3 and circuit splice between cooling fan relays No. 1 and 2. Go to «COOLING FAN FUNCTIONAL CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-hvac-system/#hvac-system__cooling-fan-functional-check) .
8. Repair open in Dark Blue wire between cooling fan relay No. 3 and circuit splice between PCM harness connector terminal No. 33 and cooling fan relay No. 2. Go to «COOLING FAN FUNCTIONAL CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-hvac-system/#hvac-system__cooling-fan-functional-check) .
9. Repair open in Light Blue wire between cooling fan relay No. 3 and circuit splice between cooling fan relay No. 2 and right cooling fan motor. Go to «COOLING FAN FUNCTIONAL CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-hvac-system/#hvac-system__cooling-fan-functional-check) .
10. Replace cooling fan relay No. 3. Go to «COOLING FAN FUNCTIONAL CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-hvac-system/#hvac-system__cooling-fan-functional-check) .

Cooling Fan Symptom Check No. 5

1. Perform cooling fan functional check, before proceeding. If cooling fan functional check has been performed, go to next step. If check has not been performed, go to «COOLING FAN FUNCTIONAL CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-hvac-system/#hvac-system__cooling-fan-functional-check) .
2. Check condition of COOL FNS (50-amp) fuse. If fuse is blown, go to step 4 . If fuse is okay, go to next step.
3. Remove cooling fan relay No. 1. Using a DVOM, measure voltage between ground and Red wire at cooling fan relay No. 1 connector. If reading is 10 volts or greater, go to step 8 . If reading is less than 10 volts, go to step 9 .
4. Turn ignition switch to LOCK position. Replace COOL FNS (50-amp) fuse. If fuse immediately blows, go to step 10 . If fuse does not blow, go to next step.
5. Turn ignition switch to ON position. Using scan tool, select OUTPUT TESTS, then FAN RELAYS. Command FAN RELAY NO. 1 ON. If COOL FNS (50-amp) fuse blows, go to step 11 . If COOL FNS (50-amp) fuse does not blow, go to next step.
6. Using scan tool, command ALL FAN RELAYS ON. If COOL FNS (50-amp) fuse blows, go to next step. If fuse does not blow, fault is not present at this time.
7. Using scan tool, exit FAN RELAYS. Replace COOL FNS (50-amp) fuse. Select FAN RELAYS. Command FAN RELAY NO. 1 ON. If left cooling fan runs, go to step 12 . If left cooling fan does not run, go to step 13 .
8. Repair open or poor connection in Black wire between ground and circuit splice between right cooling fan motor and cooling fan relay No. 2. Go to «COOLING FAN FUNCTIONAL CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-hvac-system/#hvac-system__cooling-fan-functional-check) .
9. Repair open in Red wire between COOL FNS (50-amp) fuse and cooling fan relays No. 1 and 3. Go to «COOLING FAN FUNCTIONAL CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-hvac-system/#hvac-system__cooling-fan-functional-check) .
10. Repair Red wire for a short to ground between COOL FNS (50-amp) fuse and cooling fan relay No. 1 or cooling fan relay No. 3. Go to «COOLING FAN FUNCTIONAL CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-hvac-system/#hvac-system__cooling-fan-functional-check) .
11. Repair Black wire for a short to ground between cooling fan relay No. 1 and left cooling fan motor. Go to «COOLING FAN FUNCTIONAL CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-hvac-system/#hvac-system__cooling-fan-functional-check) .
12. Replace right cooling fan motor. Go to «COOLING FAN FUNCTIONAL CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-hvac-system/#hvac-system__cooling-fan-functional-check) .
13. Replace left cooling fan motor. Go to «COOLING FAN FUNCTIONAL CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-hvac-system/#hvac-system__cooling-fan-functional-check) .

PCM CONTROLLED A/C DIAGNOSIS

Note. Since many Diagnostic Trouble Codes (DTCs) cause Powertrain Control Module (PCM) to disable A/C compressor operation, any DTCs must be repaired and cleared before proceeding. See appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE.

When A/C-Heater Programmer (ACM) requests A/C operation from 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.

1. Perform OBD system check. If On-Board Diagnostic (OBD) System Check has not been performed, see appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE.
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 ON, PCM control is okay, go to «A/C-HEATER PROGRAMMER (ACM) SELF-DIAGNOSTICS»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-hvac-system/#hvac-system__ac-heater-programmer-acm-self-diagnostics) under SELF-DIAGNOSTICS. If scan tool indicates A/C RELAY 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, then command A/C COMPRESSOR CLUTCH OFF. Listen for A/C compressor clutch to engage and disengage. If PCM control is verified, clutch engages and disengages, go to «A/C-HEATER PROGRAMMER (ACM) SELF-DIAGNOSTICS»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-hvac-system/#hvac-system__ac-heater-programmer-acm-self-diagnostics) under SELF-DIAGNOSTICS. If PCM control is not verified, perform On-Board Diagnostic (OBD) System Check. See appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE.
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 «A/C-HEATER PROGRAMMER (ACM) SELF-DIAGNOSTICS»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-hvac-system/#hvac-system__ac-heater-programmer-acm-self-diagnostics) under SELF-DIAGNOSTICS.
5. Turn ignition switch to OFF position. Disconnect PCM Blue, 80-pin connector C1. Using a DVOM, 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, 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.

TESTING

A/C SYSTEM PERFORMANCE

1. Park vehicle in shaded area. Ventilate interior. 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. Place 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»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-hvac-system/#hvac-system) table.

A/C PERFORMANCE SPECIFICATIONS

SELF-DIAGNOSTICS

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

A/C-HEATER PROGRAMMER (ACM) SELF-DIAGNOSTICS

Note. A/C-Heater Programmer (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 DTCs (current or non-current history).

Fault Detection

If ACM detects a system fault, the Vacuum Fluorescent (VF) display on climate control panel will flash one time per second for 100 seconds. (Scheme 2) If a fault occurs in outside temperature sensor circuit, VF display will not flash, but outside temperature will be displayed as a series of dashes.

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) until "ACM CODES?" is displayed. Press HI fan speed (up arrow) until DTCs are displayed. See ACM & CCP DIAGNOSTIC TROUBLE CODES table.

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 Scan Tool)

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

ACM & CCP DIAGNOSTIC TROUBLE CODES

Note. For complete PCM Diagnostic Trouble Codes (DTCs), see appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE. For IPC DTCs, see appropriate INSTRUMENT PANELS article in ACCESSORIES & EQUIPMENT.

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

To exit self-diagnostics, press OFF and WARMER, MODE or DEFOG button, or turn ignition switch to OFF position. DTCs are not cleared when exiting self-diagnostics.

DTC B1310: OUTSIDE (AMBIENT) AIR TEMPERATURE SENSOR OPEN CIRCUIT

1. Turn ignition switch to ON position. Connect scan tool. Disconnect ambient temperature sensor connector. If DTC changes from B1310 to B1311, go to next step. If DTC does not change, go to step 3 .
2. Replace ambient air temperature sensor. Clear DTC and recheck operation of climate control.
3. Using a DVOM, measure voltage between ground and ambient air temperature sensor connector terminal "B" (Light Green/Black wire). If reading is 5 volts, go to next step. If reading is not 5 volts, go to step 5 .
4. Repair open in Black wire between ambient air temperature sensor connector and ACM connector terminal D8. Clear DTC and recheck operation of climate control.
5. Using a DVOM, measure voltage between ground and ACM connector terminal C8 (Light Green/Black wire). If reading is 5 volts, go to next step. If reading is not 5 volts, go to step 7 .
6. Repair open in Light Green/Black wire between ambient air temperature sensor connector terminal "B" and ACM connector terminal C8. Clear DTC and recheck operation of climate control.
7. Check connector terminals for proper contact. If connections are okay, replace A/C-heater programmer (ACM). Clear DTC and recheck operation of climate control.

DTC B1311: OUTSIDE (AMBIENT) AIR TEMPERATURE SENSOR SHORT CIRCUIT

1. Turn ignition switch to ON position. Connect scan tool. Disconnect ambient temperature sensor connector. If DTC changes from B1311 to B1310, go to next step. If DTC does not change, go to step 3 .
2. Replace ambient air temperature sensor. Clear DTC and recheck operation of climate control.
3. Disconnect ACM and ambient sensor connectors. Connect test light between battery voltage and ACM connector terminal C8 (Light Green/Black wire). If test light comes on, go to next step. If test light does not come on, go to step 5 .
4. Repair short to ground in Light Green/Black wire between ambient air temperature sensor connector and ACM connector terminal C8. Clear DTC and recheck operation of climate control.
5. Check connector terminals for proper contact. If connections are okay, replace ACM. Clear DTC and recheck operation of climate control.

DTC B1312: A/C HIGH-SIDE TEMPERATURE SENSOR OPEN CIRCUIT

1. Turn ignition switch to ON position. Connect scan tool. Disconnect high-side temperature sensor connector. Connect jumper wire between sensor harness terminals. If DTC changes from B1312 to B1313, go to next step. If DTC does not change, go to step 3 .
2. Replace high-side temperature sensor. Clear DTC and recheck operation of climate control.
3. Using a DVOM, measure voltage between ground and high-side temperature sensor connector terminal "B" (Dark Blue wire). If reading is 5 volts, go to next step. If reading is not 5 volts, go to step 5 .
4. Repair open in Black wire between high-side temperature sensor connector and ACM connector terminal D8. Clear DTC and recheck operation of climate control.
5. Using a DVOM, measure voltage between ground and ACM connector terminal C5 (Dark Blue wire). If reading is 5 volts, go to next step. If reading is not 5 volts, go to step 7 .
6. Repair open in Dark Blue wire between high-side temperature sensor connector terminal "B" and ACM connector terminal C5. Clear DTC and recheck operation of climate control.
7. Check connector terminals for proper contact. If connections are okay, replace A/C-Heater Programmer (ACM). Clear DTC and recheck operation of climate control.

DTC B1313: A/C HIGH-SIDE TEMPERATURE SENSOR SHORT CIRCUIT

1. Turn ignition switch to ON position. Connect scan tool. Disconnect high-side temperature sensor connector. If DTC changes from B1313 to B1312, go to next step. If DTC does not change, go to step 3 .
2. Replace high-side temperature sensor. Clear DTC and recheck operation of climate control.
3. Disconnect ACM and high-side temperature sensor connectors. Connect test light between battery voltage and ACM connector terminal C5. If test light comes on, go to next step. If test light does not come on, go to step 5 .
4. Repair short to ground in Dark Blue wire between high-side temperature sensor connector and ACM connector terminal C5. Clear DTC and recheck operation of climate control.
5. Check connector terminals for proper contact. If connections are okay, replace ACM. Clear DTC and recheck operation of climate control.

DTC B1314: EVAPORATOR INLET TEMPERATURE SENSOR OPEN CIRCUIT

1. Turn ignition switch to ON position. Connect scan tool. Disconnect evaporator inlet (low-side) temperature sensor connector. Connect a jumper wire between terminals of harness connector. If DTC changes from B1314 to B1315, go to next step. If DTC does not change, go to step 3 .
2. Replace low-side temperature sensor. Clear DTC and recheck operation of climate control.
3. Using a DVOM, measure voltage between ground and low-side temperature sensor connector Gray wire terminal. If reading is 5 volts, go to next step. If reading is not 5 volts, go to step 5 .
4. Repair open in Black wire between low-side temperature sensor connector and ACM connector terminal D8. Clear DTC and recheck operation of climate control.
5. Using a DVOM, measure voltage between ground and ACM connector terminal C6 (Gray wire). If reading is 5 volts, go to next step. If reading is not 5 volts, go to step 7 .
6. Repair open in Gray wire between low-side temperature sensor connector and ACM connector terminal C6. Clear DTC and recheck operation of climate control.
7. Check connector terminals for proper contact. If connections are okay, replace ACM. Clear DTC and recheck operation of climate control.

DTC B1315: EVAPORATOR INLET TEMPERATURE SENSOR SHORT CIRCUIT

1. Turn ignition switch to ON position. Connect scan tool. Disconnect low-side temperature sensor connector. If DTC changes from B1315 to B1314, go to next step. If DTC does not change, go to step 3 .
2. Replace low-side temperature sensor. Clear DTC and recheck operation of climate control.
3. Disconnect ACM and low-side temperature sensor connectors. Connect test light between battery voltage and ACM connector terminal C6 (Gray wire). If test light comes on, go to next step. If test light does not come on, go to step 5 .
4. Repair short to ground in Gray wire between low-side temperature sensor connector and ACM connector terminal C6. Clear DTC and recheck operation of climate control.
5. Check connector terminals for proper contact. If connections are okay, replace ACM. Clear DTC and recheck operation of climate control.

DTC B1316: IN-CAR TEMPERATURE SENSOR OPEN CIRCUIT

1. Turn ignition switch to ON position. Connect scan tool. Disconnect in-car sensor connector. Connect fused jumper between sensor connector terminals. If DTC changes from B1316 to B1317, go to next step. If DTC does not change, go to step 3.
2. Replace in-car temperature sensor. Clear DTC and recheck operation of climate control.
3. Using a DVOM, measure voltage between ground and in-car temperature sensor connector Dark Green wire terminal. If reading is 5 volts, go to next step. If reading is not 5 volts, go to step 5.
4. Repair open in Black wire between in-car temperature sensor connector and splice. Clear DTC and recheck operation of climate control.
5. Using a DVOM, measure voltage between ground and ACM connector terminal D9 (Dark Green wire). If reading is 5 volts, go to next step. If reading is not 5 volts, go to step 7.
6. Check connector terminals for proper contact. If connections are okay, replace ACM. Clear DTC and recheck operation of climate control.
7. Using a DVOM, measure voltage between ground and instrument panel in-line harness connector, located under passenger side of instrument panel next to glove box, cavity "C" (Dark Green wire). (Scheme 6) If reading is 5 volts, go to next step. If reading is not 5 volts, go to step 9.
8. Repair open in Dark Green wire between instrument panel in-line harness connector cavity "C" and in-car temperature sensor connector. Clear DTC and recheck operation of climate control.
9. Repair open in Dark Green wire between instrument panel in-line harness connector cavity "C" and ACM connector terminal D9. Clear DTC and recheck operation of climate control.

DTC B1317: IN-CAR TEMPERATURE SENSOR SHORT CIRCUIT

1. Turn ignition switch to ON position. Connect scan tool. Disconnect in-car temperature sensor connector. Connect fused jumper between sensor connector terminals. If DTC changes from B1317 to B1316, go to next step. If DTC does not change, go to step 3.
2. Replace in-car temperature sensor. Clear DTC and recheck operation of climate control.
3. Disconnect ACM and in-car temperature sensor connectors. Connect test light between battery voltage and ACM connector terminal D9 (Dark Green wire). If test light comes on, go to next step. If test light does not come on, go to step 5.
4. Check connector terminals for proper contact. If connections are okay, replace ACM. Clear DTC and recheck operation of climate control.
5. Connect test light between ground and instrument panel in-line harness connector, located under passenger side of instrument panel next to glove box, cavity "C" (Dark Green wire). (Scheme 6) If test light comes on, go to next step. If test light does not come on, go to step 7.
6. Repair short to ground in Dark Green wire between instrument panel in-line harness connector cavity "C" and in-car temperature sensor connector. Clear DTC and recheck operation of climate control.
7. Repair short to ground in Dark Green wire between instrument panel in-line harness connector cavity "C" and ACM connector terminal D9. Clear DTC and recheck operation of climate control.

Scheme 6

DTC B1318: SUN LOAD SENSOR OPEN CIRCUIT

1. Turn ignition switch to ON position. Connect scan tool. Disconnect sun load sensor connector. Connect fused jumper between sensor connector terminals. If DTC changes from B1318 to B1319, go to next step. If DTC does not change, go to step 3.
2. Replace sun load (solar) sensor. Clear DTC and recheck operation of climate control.
3. Using a DVOM, measure voltage between ground and sun load temperature sensor connector Light Blue/Black wire terminal. If reading is 5 volts, go to next step. If reading is not 5 volts, go to step 5.
4. Repair open in Black wire between sun load sensor connector and splice (ground). Clear DTC and recheck operation of climate control.
5. Using a DVOM, measure voltage between ground and ACM connector terminal C7 (Light Blue/Black wire). If reading is 5 volts, go to next step. If reading is not 5 volts, go to step 7.
6. Check connector terminals for proper contact. If connections are okay, replace ACM. Clear DTC and recheck operation of climate control.
7. Using a DVOM, measure voltage between ground and instrument panel in-line harness connector, located under passenger side of instrument panel, next to glove box, cavity "E" (Light Blue/Black wire). (Scheme 6) If reading is 5 volts, go to next step. If reading is not 5 volts, go to step 9.
8. Repair open in Light Blue/Black wire between instrument panel in-line harness connector cavity "E" and sun load sensor connector. Clear DTC and recheck operation of climate control.
9. Repair open in Light Blue/Black wire between instrument panel in-line harness connector cavity "E" and ACM connector terminal C7. Clear DTC and recheck operation of climate control.

DTC B1319: SUN LOAD SENSOR SHORT CIRCUIT

1. Turn ignition switch to ON position. Connect scan tool. Disconnect sun load sensor connector. Connect fused jumper between sensor connector terminals. If DTC changes from B1319 to B1318, go to next step. If DTC does not change, go to step 3 .
2. Replace sun load (solar) sensor. Clear DTC and recheck operation of climate control.
3. Disconnect ACM and sun load temperature sensor connectors. Connect test light between battery voltage and ACM connector terminal C7 (Light Blue/Black wire). If test light comes on, go to next step. If test light does not come on, go to step 5 .
4. Check connector terminals for proper contact. If connections are okay, replace ACM. Clear DTC and recheck operation of climate control.
5. Repair short to ground in Light Blue/Black wire between sun load sensor connector and ACM connector terminal C7.

DTC B1340: AIR MIX DOOR NO. 1 MOVEMENT FAILURE (DRIVER)

1. Start engine and install scan tool. Energize suspect actuator with climate control panel while observing scan tool data. If driver's actuator is being commanded to proper high and low values, go to step 3 . If driver's actuator is not being commanded or is not within values, go to next step.
2. Check connector terminals for proper contact. If connections are okay, replace ACM. Clear DTC and recheck operation of climate control.
3. Compare scan tool high and low actual values against actuator values. Values should be within 0-5 percent of each other. If scan tool data is within values, go to next step. If scan tool data is not within values, go to step 5 .
4. Replace ACM. Clear DTC and recheck operation of climate control.
5. Turn ignition switch to OFF and then back to ON position (engine off). Inspect driver's actuator linkage and air mix door for binding or obstructions. If okay, go to step 7 . If problem was found, go to next step.
6. Repair binding or clear obstruction. Adjust linkage, see «ADJUSTMENTS»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-hvac-system/#hvac-system) . Clear DTC and recheck operation of climate control.
7. Disconnect driver's air mix door actuator connector. Using a DVOM, check between ground and following circuits. Check for 5 volts at driver's actuator connector terminal No. 10 (Gray wire). Check for battery voltage at actuator connector terminal No. 5 (Light Green wire). Check Light Blue/Black wire, Red wire, and Black wire for opens. If any circuits are suspect, go to next step. If circuits are okay, go to step 9 .
8. Repair suspect circuit. Clear DTC and recheck operation of climate control.
9. Replace driver's air mix door actuator. Clear DTC and recheck operation of climate control.

DTC B1341: AIR MIX DOOR NO. 2 MOVEMENT FAILURE (PASSENGER)

1. Start engine and install scan tool. Energize suspect actuator with climate control panel while observing scan tool data. If passenger actuator is being commanded to proper high and low values, go to step 3 . If passenger actuator is not being commanded or is not within values, go to next step.
2. Check connector terminals for proper contact. If connections are okay, replace ACM. Clear DTC and recheck operation of climate control.
3. Compare scan tool high and low actual values against actuator values. Commanded values should range between 0-100 percent. Actual values should not vary more than 5 percent of commanded value. If scan tool data is within values, go to next step. If scan tool data is not within values, go to step 5 .
4. Replace ACM. Clear DTC and recheck operation of climate control.
5. Turn engine switch to OFF and then back to ON position (engine off). Inspect passenger actuator linkage and air mix door for binding or obstructions. If okay, go to step 7 . If problem was found, go to next step.
6. Repair binding or clear obstruction. Adjust linkage, see ADJUSTMENTS. Clear DTC and recheck operation of climate control.
7. Disconnect passenger air mix door actuator connector. Using a DVOM, check between ground and following circuits. Check for 5 volts at passenger actuator connector terminal No. 10 (Gray wire). Check for battery voltage at passenger actuator connector terminal No. 5 (Light Green wire). Check Dark Blue/White wire, Black wire, and Yellow/Black wire for opens. If any circuits are suspect, go to next step. If circuits are okay, go to step 9 .
8. Repair suspect circuit. Clear DTC and recheck operation of climate control.
9. Replace passenger air mix door actuator. Clear DTC and recheck operation of climate control.

DTC B1347: VERY LOW A/C REFRIGERANT WARNING

Note. Ambient temperature must be greater than 42°F (5°C) before beginning diagnostic procedure.

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 notify operator. ACM determines state of charge by monitoring temperature change in low-side temperature sensor during initial moments of each compressor engagement. If temperature change is too great, a very low refrigerant counter in ACM is monitored. 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.

Failure Conditions

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

Actions Taken

1. A/C compressor is disabled until DTC is cleared.
2. DIC displays VERY LOW A/C REFRIGERANT - A/C COMPRESSOR OFF message.

Testing Procedure

1. Leak test A/C system. Connect scan tool. Display LOW PRESSURE SWITCH on scan tool. Monitor display while wiggling low-pressure switch wiring and connectors. If scan tool indicates switch staying ON, go to next step. If scan tool indicates switch staying OFF, go to step 3 .
2. Repair intermittent open or short in Pink wire between CRUISE (10-amp) fuse and A/C low-pressure switch connector. Or an open or shorted condition in Dark Green wire between ACM connector terminal D14 and A/C low-pressure switch connector. Check terminal contacts at connectors. If all circuits and terminals are okay, replace low-pressure switch.
3. Connect A/C pressure manifold gauge set to service fittings. Start engine and set climate control panel to AUTO with temperature setting at 75°F (23°C). Use scan tool, compare manifold gauge pressures to low-side and high-side temperature sensor readings to refrigerant temperature/pressure conversion chart. See «REFRIGERANT TEMPERATURE/PRESSURE CONVERSION»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-hvac-system/#hvac-system) table. If calculated pressure from temperature readings and actual gauge pressures are within 10 percent of each other, go to step 5 . If calculated pressure is not within 10 percent of gauge pressure, go to next step.
4. Check for restriction in A/C system between temperature sensor and service fitting that is not within specification. Repair as necessary. Clear DTC and recheck operation of climate control.
5. Discharge A/C system, using approved refrigerant recovery/recycling equipment. Remove orifice tube and inspect for debris. Evacuate and charge A/C system. Clear DTC and recheck climate control operation.

Note. Variance in temperature sensor readings may cause a false DTC to set. Let vehicle sit overnight and enter diagnostics without starting vehicle. Sensor displays should be within 36°F (2°C) of each other.

DTC B1348: VERY LOW A/C REFRIGERANT PRESSURE CONDITION

Note. Ambient temperature must be greater than 42°F (5°C) before beginning diagnostic procedure.

In the process of controlling compressor clutch, ACM monitors certain inputs for indication of low refrigerant charge. ACM monitors low refrigerant pressure switch (which is normally closed) at terminal 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. A/C compressor is disabled until DTC is cleared.
2. DIC displays VERY LOW A/C REFRIGERANT - A/C COMPRESSOR OFF message.

1. Turn ignition switch to ON position. Connect scan tool. Display LOW PRESSURE SWITCH on scan tool. If scan tool indicates switch HI, go to next step. If scan tool indicates switch LO, go to step 7 .
2. Connect A/C pressure gauge set to service fittings. Start engine and set climate control panel to AUTO with temperature setting at 75°F (23°C). Using scan tool, compare manifold gauge pressures to low and high-side temperature sensor readings of refrigerant temperature/pressure conversion chart. See «REFRIGERANT TEMPERATURE/PRESSURE CONVERSION»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-hvac-system/#hvac-system) table. If calculated pressure from temperature readings and actual gauge pressures are within 10 percent of each other, go to step 4 . If calculated pressure is not within 10 percent, go to next step.
3. Check for restriction in A/C system between temperature sensor and service fitting side that is not within specification. Repair as necessary. Clear DTC and recheck operation of climate control.
4. Display LOW PRESSURE SWITCH on scan tool. Monitor scan tool display while wiggling low-pressure switch wiring and connectors. If scan tool indicates switch staying HI, go to next step. If scan tool indicates switch cycling from HI to LO, go to step 6 .
5. Replace low-pressure switch. Clear DTC and recheck operation of climate control.
6. Repair intermittent open or short in Pink wire between CRUISE (10-amp) fuse and A/C low-pressure switch connector, or in Dark Green wire between ACM connector terminal D14 and A/C low-pressure switch connector. Check terminal contacts at connectors. If all circuits and terminals are okay, replace low-pressure switch. Clear DTC and recheck operation of climate control.
7. Remove low-pressure switch connector. Connect fused jumper between sensor connector terminals. Monitor scan tool display. If sensor data switches to HI, go to step 11 . If switch data remains LO, go to next step.
8. Using a DVOM, measure voltage between ground and fused jumper. If reading is less than 8 volts, go to next step. If reading is greater than 8 volts, go to step 10 .
9. Repair open or short to ground in Pink wire between CRUISE (10-amp) fuse and A/C low-pressure switch connector. Check for open CRUISE (10-amp) fuse and replace as necessary. Clear DTC and recheck operation of climate control.
10. Check for open in Dark Green wire between ACM connector terminal D14 and A/C low-pressure switch connector. Check terminal contacts at connectors. If all circuits and terminals are okay, replace ACM. Clear DTC and recheck operation of climate control.
11. Connect A/C pressure gauge to low-side pressure fitting. If pressure is less than 10 psi (0.7 kg/cm 2 ), go to next step. If pressure is greater than 10 psi (0.7 kg/cm 2 ), go to step 13 .
12. Leak test system and repair leak. Evacuate and charge A/C system. Clear DTC and recheck operation of climate control.
13. Check terminal contacts at low-pressure switch. If terminals are okay, replace low-pressure switch. Clear DTC and recheck operation of climate control.

REFRIGERANT TEMPERATURE-TO-PRESSURE CONVERSION

DTC B1350: HIGH ENGINE COOLANT TEMPERATURE

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. See appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE. If PCM is operating properly, replace ACM. Ensure system is operating properly.

DTC B1982: SOURCE/BATTERY VOLTAGE HIGH

DTC B1982 will set if ignition switch is on and 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.

Turn ignition switch to ON position. Using scan tool, check battery voltage with engine at normal operating temperature. If displayed battery voltage is less than 16 volts, replace A/C-heater programmer (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.

1. Turn ignition switch to ON position. 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 A/C-heater programmer (ACM). Ensure system is operating properly.
2. Using a DVOM, 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.

U1016: LOSS OF PCM SERIAL COMMUNICATIONS

DTC U1016 will set if ignition switch 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.

1. Turn ignition switch to ON position. Using scan tool, attempt to establish communications with PCM.
2. Check for an open or shorted condition in Purple wire between PCM connector terminal No. 59 and ACM connector terminal D4.
3. Ensure PCM is properly grounded and has power to appropriate terminals.
4. If multiple class 2 DTCs are current, check Purple wire between PCM connector terminal No. 59 and ACM connector terminal D4 for short to ground or voltage. See appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT.
5. Ensure PCM is operating properly. See appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE. 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 appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE.

DTC U1064: LOSS OF PZM SERIAL DATA COMMUNICATIONS

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).

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

1. Turn ignition switch to ON position. Using scan tool, attempt to establish communications with PZM.
2. Check for an open or shorted condition in Purple wire between PCM connector terminal No. 59 and ACM connector terminal D4.
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 appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT.
5. If multiple class 2 serial data DTCs are current, check for short to ground or voltage in Purple wire between PCM connector terminal No. 59 and ACM connector terminal D4. See appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT.
6. Ensure PZM is operating properly. See appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT. If PZM is operating properly, replace ACM or CCP, depending upon which component has set a DTC U1064.

DTC U1096: LOSS OF IPC SERIAL DATA COMMUNICATIONS

DTC U1096 will set if ignition switch 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 DTC U1096 is dependent upon other system symptoms or DTCs present.

1. Turn ignition switch to ON position. Using scan tool, attempt to establish communications with IPC.
2. Check for an open or shorted condition in Purple wire between PCM connector terminal No. 59 and ACM connector terminal D4.
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 (BCM) and ACM were functional when DTC was set, but could not communicate with each other. See appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT.
5. If multiple Class 2 DTCs are current, check for short to ground or voltage in Purple wire between PCM and ACM. See appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT.

DTC U1152: LOSS OF ACM SERIAL DATA COMMUNICATIONS

DTC U1152 will set if ignition switch is in ON position and CCP has lost data communication with A/C-Heater Programmer (ACM). Diagnosis of DTC U1152 is dependent upon other system symptoms or DTCs present.

1. Turn ignition switch to ON position. Using scan tool, attempt to establish communications with ACM.
2. Check for an open or shorted condition in Purple wire between PCM connector terminal No. 59 and ACM connector terminal D4.
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 in Purple wire between PCM connector terminal No. 59 and ACM connector terminal D4. See appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT.

DTC U1153: LOSS OF CCP SERIAL DATA COMMUNICATIONS

DTC U1153 will set if ignition switch is in ON position and ACM has lost data communication with CCP. Diagnosis of DTC U1153 is dependent upon other system symptoms DTCs present.

1. Turn ignition switch to ON position. Using scan tool, attempt to establish communications with Climate Control Panel (CCP).
2. Check for an open or shorted condition in Purple wire between PCM connector terminal No. 59 and ACM connector terminal D4.
3. Ensure CCP is connected to power and ground.
4. CCP DTC 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 Purple wire between PCM connector terminal No. 59 and ACM connector terminal D4. See appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT.

DTC U1169: LOSS OF MMM SERIAL DATA COMMUNICATIONS

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

1. Using scan tool, attempt to establish communications with Memory Mirror Module (MMM).
2. Check for an open or shorted condition in Purple wire between PCM connector terminal No. 59 and ACM connector terminal D4.
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 Purple wire between PCM connector terminal No. 59 and ACM connector terminal D4. See appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT.

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 modules communicate with ACM or CCP.

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 and DTC P1605 have not been set, go to next step.
3. Check option programing in IPC. Ensure correct options have been programmed into IPC. See appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT. If IPC has been programed correctly, go to next step.
4. Ensure 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 appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT.

REMOVAL & INSTALLATION

Disconnect negative battery cable. Remove right sound insulator. Remove glove box. See GLOVE BOX. Disconnect programmer electrical and vacuum connectors. Remove A/C-heater programmer. (Scheme 7) 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 hold down strap. Remove accumulator. Add 3 ounces of NEW refrigerant oil to replacement accumulator. To install, reverse removal procedure. Evacuate and charge A/C system.

Scheme 7

Scheme 8

1. Remove negative battery cable. Remove left and right hush panels. Remove console. See «AUXILIARY (REAR) BLOWER MOTOR»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-hvac-system/#hvac-system).
2. Disable air bag system. Remove defroster grille. Disconnect sun load and headlamp auto control sensors. Remove screws behind defroster grille opening. Remove instrument panel outlet vents using small, flat-blade screwdriver. Remove screws from vent openings. Remove upper trim panel on passenger side by pressing down on forward edge while pulling upward and back on rear edge of panel (DeVille). Pull upward and back on rear edge of upper trim panel to remove (Eldorado).
3. Pull down to disengage clips for steering column opening trim, remove screws retaining bracket. Disconnect instrument panel cluster connectors. Remove screws and cluster. Remove screws retaining left and right side wood trim panels and remove panels by pulling gently outward. Remove glove box assembly. See «GLOVE BOX»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-hvac-system/#hvac-system).
4. For vehicles not equipped with center console, go to next step. Pull on instrument panel center trim to remove. Open ashtray and remove bolts retaining ashtray. Disconnect electrical connector and remove ashtray. Remove Driver's Information Switch (DIS) by using small, flat-blade screwdriver to pry on ends. Disconnect electrical connector for switch and remove.
5. Remove radio assembly and brackets. Disconnect electrical connectors. Pull firmly on headlight switch to remove from instrument panel, and disconnect electrical connector. Remove screws retaining hood release handle, and slide forward to release. Disconnect cable from handle and remove.
6. Disconnect electrical connectors from steering column. Remove steering column intermediate shaft coupling. Remove upper and lower steering column bolts/nuts. Remove steering column. Remove screws retaining instrument panel. (Scheme 8) Disconnect remaining electrical connectors. Remove instrument panel.
7. Remove parking brake assembly. Remove center brace. Remove hinge pillar tie bar from vehicle. (Scheme 8)
8. Remove air distribution assembly. Remove inside temperature sensor aspirator hose. Remove antenna lead. Remove fuel filler door release and trunk release connectors. Remove instrument panel wiring harness retaining nuts and pull harness forward.
9. Remove windshield defroster assembly and vacuum lines. Remove acoustic padding retainers and fasteners in vicinity of air inlet assembly. Remove air inlet assembly mounting screws. (Scheme 9) Remove air inlet assembly.

Scheme 9

1. Remove glove box. See «GLOVE BOX»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-hvac-system/#hvac-system). Unsnap rod from plastic retainer on actuator arm. Remove actuator mounting screws. Disconnect electrical connector. Remove actuator. (Scheme 7) 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 air temperature sensor. (Scheme 10) To install, reverse removal procedure.

Scheme 10

Removal

1. Disconnect negative battery cable. Remove cross-tower brace. Disconnect 4 ignition control module electrical connectors. Position cross-car harness aside. Disconnect No. 5 and No. 7 cylinder 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 11) 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 11)
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. CAUTION: Failure to position spark plug wires at least one inch (25 mm) from blower motor may result in improper operation or failure of blower motor.

Scheme 11

1. Remove center console storage compartment by pulling up and out. Remove shifter handle retaining clip and handle. Pull on shifter trim plate to remove. Remove ashtray and disconnect electrical connector. Remove Driver's Information Switch (DIS) by using small screwdriver to pry on ends. Disconnect electrical connector for switch and remove.
2. Remove screws from radio/climate control panel bracket and pull out enough to disconnect electrical connectors and antenna cable. Remove screws retaining center console to instrument panel. Remove nuts through storage compartment opening inside rear of center console. Disconnect console blower air supply duct. (Scheme 9)
3. Slide center console up to disconnect electrical connectors. Slide console back enough to clear shifter mechanism and remove console.
4. Remove screws attaching blower motor to assembly and remove blower motor. To install, reverse removal procedure. (Scheme 12)

Scheme 12

Removal & Installation (Instrument Panel Mounted)

1. On models with Climate Control Panel (CCP) mounted above center console, remove center console storage compartment by pulling up and out. Remove shifter handle retaining clip and handle. Pull on shifter trim plate to remove. Remove ashtray and disconnect electrical connector. Remove driver's information switch (located above radio) by using small, flat-blade screwdriver to pry on ends. Disconnect electrical connector for switch and remove.
2. On all models, remove trim plate for radio. Remove mounting screws for radio/CCP bracket. Pull out radio/CCP bracket assembly far enough to disconnect electrical connectors and antenna cable.
3. Remove nuts retaining CCP to radio/CCP bracket assembly. Remove CCP from radio/CCP bracket assembly. To install, reverse removal procedure.

Removal & Installation (Passenger Armrest Mounted)

Using a flat-blade screw driver or trim stick, remove passenger climate control panel from passenger's armrest (if equipped). Disconnect electrical connections. Remove passenger's climate control panel. To install, reverse removal procedure.

1. Remove center console. See «AUXILIARY (REAR) BLOWER MOTOR»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-hvac-system/#hvac-system). Remove screws at rear of console at upper end and lower sides to remove console rear cover. Disconnect electrical connector.
2. Use small, flat-blade screwdriver to pry on ends to remove left and right vents from side of rear cover. Remove rear air outlet duct. Pull off blower control knob. Remove screws attaching blower control to rear cover. Remove blower control panel. (Scheme 12) To install, reverse removal procedure.

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 and measure volume of 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 two ounces 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 AIR BAG SYSTEM SAFETY article in GENERAL SERVICING. 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/deville-concours/i-final-1999-1999/remont/automatic-hvac-system/#hvac-system). Disconnect vacuum and electrical connectors. Remove ACM. See «A/C-HEATER PROGRAMMER»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-hvac-system/#hvac-system). (Scheme 7)
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. See «HEATER CORE»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-hvac-system/#hvac-system). Remove cross car brace (bolted to strut towers). 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/deville-concours/i-final-1999-1999/remont/automatic-hvac-system/#hvac-system). 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 2 ounces of NEW refrigerant oil to replacement evaporator. Evacuate and charge A/C system.

Scheme 13

1. Disable air bag system. See AIR BAG SYSTEM SAFETY article in GENERAL SERVICING. 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/deville-concours/i-final-1999-1999/remont/automatic-hvac-system/#hvac-system). Remove right lower sound insulator. Disconnect electrical connectors. Remove ACM. See «A/C-HEATER PROGRAMMER»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-hvac-system/#hvac-system). (Scheme 7)
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 «TEMPERATURE AIR MIX VALVE»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-hvac-system/#hvac-system) under ADJUSTMENTS.

HIGH-PRESSURE SWITCH

Note. High-pressure switch is mounted on Schrader valve. System does not need to be discharged when replacement is required.

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 when replacement is required.

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 sun load sensor screws. Remove sun load 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 14

Scheme 15

Scheme 16

Automatic A/C-Heater System Wiring Diagram (DeVille & Eldorado - 1 Of 2). Scheme 17

Automatic A/C-Heater System Wiring Diagram (DeVille & Eldorado - 2 Of 2). Scheme 18

See also:
• A/C-HEATER PROGRAMMER (ACM) SELF-DIAGNOSTICS
• CLIMATE CONTROL PANEL TEMPERATURE & MODE SETTINGS
• PURGE MODE
• DUAL ZONE SWITCH DIAGNOSIS
• COOLING FAN FUNCTIONAL CHECK
• COOLING FAN SYMPTOM CHECK NO. 1
• COOLING FAN SYMPTOM CHECK NO. 2
• COOLING FAN SYMPTOM CHECK NO. 3
• COOLING FAN SYMPTOM CHECK NO. 4
• COOLING FAN SYMPTOM CHECK NO. 5
• B1310
• B1311
• B1312
• B1313
• B1314
• B1315
• B1316
• B1317
• B1318
• B1319
• B1340
• B1341
• B1347
• B1348
• B1350
• B1982
• U1016
• U1064
• U1096
• U1153
• U1169
• U1255
• U1152