HVAC System - Automatic Cadillac DeVille Concours

A/C SYSTEM SPECIFICATIONS

Note. Air Conditioning Programmer (ACP) may also be referred as Air Conditioning Module (ACM). Body Control Module (BCM) may also be referred as Platform Zone Module (PZM).

A/C SYSTEM SPECIFICATIONS

DESCRIPTION

The Electronic Climate Control (ECC) system automatically regulates and maintains selected in-car 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 Center (CCC) is the main control for selecting in-car comfort levels. (Scheme 1)or (Scheme 2).

Main components of the ECC system are as follows: Air Conditioning Programmer (ACP); Powertrain Control Module (PCM); Heating, Ventilation and Air Conditioning (HVAC) module; refrigerant system; and temperature sensors.

BLOWER FAN CONTROL

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

Eldorado & Seville

The blower fan control, located at rear of console, has 5 positions: off, low, medium, medium high and high.

TEMPERATURE SETTINGS

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

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

OFF Mode

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

Because fan and A/C compressor do not operate, set temperature will probably not be reached. When in OFF mode, CCC will display only outside temperature.

ECON Mode

In this mode, A/C compressor does not operate. System will adjust to selected temperature, but temperature inside vehicle can only be as cool as outside temperature.

AUTO Mode

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

In this mode, system can use any blower speed, any air inlet position, and any air outlet position to reach selected temperature. Depending on heating or cooling requirement, air will enter passenger compartment from bi-level registers and vents, upper registers only, or lower vents only.

DEFOG Mode

In this setting, air is divided equally between floor and defroster vents. Compressor is allowed to cycle at lower temperatures to dehumidify passenger compartment air.

Defrost Mode

In this setting, everything is controlled automatically; most air is delivered to windshield.

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

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

RECIRC Mode

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

Scheme 1

Scheme 2

AIR DELIVERY SYSTEM

The Heating, Ventilation and Air Conditioning (HVAC) assembly incorporates most of the air conditioning components into one assembly. The function of the air delivery system is to distribute airflow throughout the vehicle. Major components of the HVAC module include air inlet valve, blower motor, evaporator core, air-mix valve, heater core, up-down valve, and A/C-defrost valve. (Scheme 3) Eldorado and Seville have an auxiliary blower in the console to direct air to rear seat occupants.

Scheme 3

AIR CONDITIONING PROGRAMMER (ACP)

The ACP is located behind the glove box, attached to bracket next to right end of HVAC module assembly. It can be identified by the vacuum and electrical connections attached to it. The ACP controls temperature regulation through control of the air-mix valve motor and the 4 vacuum solenoids. The ACP is equipped with a self-diagnostic function.

Diagnostic Trouble Codes (DTCs)

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

TEMPERATURE SENSOR INPUTS

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

In-Car Temperature Sensor

This sensor is located in the instrument panel, left of center. To provide accurate in-car 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 ACP and displayed on climate control center.

Coolant Temperature Sensor

The coolant temperature sensor is located in a coolant passage of the intake manifold. Its output is monitored by the PCM, which in turn sends a signal to the ACP 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 ACP can determine low side pressure based on the pressure-temperature relation of R-134a refrigerant.

Sunload Sensor

The sunload sensor is located under the center defroster grille, at base of windshield. This sensor uses a light sensitive photocell to measure heat load of sun on vehicle. The ACP processes this signal together with temperature signals to determine the cooling necessary for maintaining selected interior temperature.

HIGH REFRIGERANT PRESSURE SWITCH

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

LOW REFRIGERANT PRESSURE SWITCH

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

PROGRAM NUMBER

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

The program number determines the proper air delivery mode and blower speed, and is also a factor in determining air-mix valve position. A program number of zero indicates maximum system cooling, and a program number of 99 represents maximum heating. Program number can be observed using Tech 1 scan tester.

AIR-MIX VALVE POSITION

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

BLOWER SPEED CONTROL

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

AIR DELIVERY MODE CONTROL

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

Note. When using Tech 1 scan tester, it is possible to override the following modes to observe complete operation of each mode.

Max A/C Mode

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

A/C Mode

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

Bi-Level Mode

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

Heater Mode

Air flows through heater outlets with bleed to defrost outlets.

In this setting, air is divided equally between floor and defroster vents. Compressor is enabled to dehumidify passenger compartment air if temperature is more than 40°F (4.5°C). This mode can be entered manually by pressing DEFOG button on standard control panel or mode select button on optional dual zone control panel.

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

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

IPC Cooling Mode

When necessary, blower will turn on and direct air to A/C outlets to cool Instrument Panel Cluster (IPC) in order to prevent damage to electronic components. IPC cooling is enabled under following conditions: ignition on and engine off, or engine running and HVAC off, in-car temperature more than 125°F (51°C), and blower override mode not operating. When enabled, minimum run time is 4 minutes. IPC cooling mode is disabled if in-car temperature is less than 121°F (50°C), or engine is running and HVAC is not off. IPC cooling is not available during self-diagnostics 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 turn on, if certain conditions exist. 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 DEFOG, DEFROST, or HI setting will prevent purge modes from initiating.

COMPRESSOR CLUTCH CONTROL

The PCM controls the compressor clutch based on inputs to PCM and ACP. When all inputs to PCM and ACP are within acceptable values, ACP signals the PCM to engage the compressor clutch. Once the A/C clutch is engaged, minimum compressor clutch on time is determined by either of following modes.

Extended Compressor At Idle

When vehicle speed drops to less than 15 MPH, minimum clutch on time is increased to about 45 seconds, providing a smoother idle at low vehicle speeds with A/C operating.

Minimum Compressor On Time

When vehicle is operating at speeds greater than 20 MPH, minimum on time is limited to 4-6 seconds before the ACP will allow compressor clutch disengagement.

After minimum on time has expired, ACP will request PCM to disengage compressor clutch only if low-side temperature is less than 30°F (-1°C). When low-side temperature reaches 45-50°F (7-10°C), ACP cycles the compressor on again.

IDLE SPEED CONTROL

The PCM can modify engine idle during A/C operation to minimize the effects of compressor operation on vehicle idle. When PCM receives a clutch engagement signal from ACP, it adjusts idle speed control motor in anticipation of increased engine load.

LOW REFRIGERANT MESSAGE

ACP also monitors inputs which would indicate low refrigerant charge. If system charge level drops to approximately 1/4 of system capacity, a VERY LOW A/C REFRIGERANT - COMPRESSOR OFF message will be displayed, and ACP will store a DTC.

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

1. Remove right sound insulator. Remove glove box. See GLOVE BOX under REMOVAL & INSTALLATION. Start vehicle, and set CCC 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), unplug in-car temperature sensor.
2. Allow at least 45 seconds for programmer arm to reach full heat position. Pull link rod from retainer on programmer output arm. (Scheme 3) Gently pull driver-side air-mix valve link toward programmer until air-mix valve hits stop. Push threaded portion of link into slot of driver-side temperature valve crank.

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

1. Remove right sound insulator. Remove glove box. See GLOVE BOX under REMOVAL & INSTALLATION. Pull link rod from retainer on programmer output arm. (Scheme 3) Start vehicle, and set CCC panel to 90°F (32°C) temperature setting.
2. Allow at least 45 seconds for programmer arm to reach full heat position. Set air-mix valve to maximum heat position, and snap link rod into programmer output crank retainer. (Scheme 3)

Link Rod Adjustment (Standard A/C System)

1. Remove right sound insulator. Remove glove box. See GLOVE BOX under REMOVAL & INSTALLATION. Start vehicle, and set CCC panel to 90°F (32°C) temperature setting. Pull link rod from retainer on programmer output arm.
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 4)

Scheme 4

TROUBLE SHOOTING

COOLING FANS

See appropriate wiring diagram for aid in trouble shooting cooling fan problems.

Note. All A/C system diagnostics should begin with ECC SYSTEM CHECK. Perform check with engine running and warmed to normal operating temperature. Ambient temperature must be at least 43°F (6°C).

Standard A/C System

1. Correct any obvious faults such as low coolant level, coolant leaks, faulty aspirator hose, refrigerant leaks, or vacuum leaks. To ensure A/C controls are operating properly, perform standard A/C system response test. See STANDARD A/C SYSTEM RESPONSE table.
2. Turn A/C on. Set temperature to full cold and blower to maximum speed. Check for DTCs. See ACP SELF-DIAGNOSTICS under TESTING. If no DTCs are displayed, go to next step. If any DTCs are displayed, go to appropriate DTC chart. See TROUBLE SHOOTING CHARTS.
3. If compressor and/or blower do not operate, or interior temperature is not as selected, use ECC trouble shooting charts to diagnose problem by symptom. See ECC TROUBLE SHOOTING CHART DIRECTORY table.

Note. IF A/C compressor does not operate, go to CHART 1 NO COMPRESSOR OPERATION. See TROUBLE SHOOTING CHARTS.

Dual Zone A/C System

1. Correct any obvious faults such as low coolant level, coolant leaks, faulty aspirator hose, refrigerant leaks, or vacuum leaks. Turn ignition on with engine off. Using Tech 1 scan tester, check for DTCs. If current DTCs are displayed, go to appropriate DTC chart. See TROUBLE SHOOTING CHARTS.
2. If history, or current and history DTCs are stored, go to step 4). If no DTCs are displayed, perform dual zone A/C system response test. See DUAL ZONE A/C SYSTEM RESPONSE table. If system does not operate properly, go to next step.
3. If compressor and/or blower do not operate, or interior temperature is not as selected, use ECC trouble shooting charts to diagnose problem by symptom. See ECC TROUBLE SHOOTING CHART DIRECTORY table.
4. Record all DTCs. Using Tech 1, clear DTCs. Perform dual zone A/C system response test. See DUAL ZONE A/C SYSTEM RESPONSE table. Using Tech 1 scan tester, check for DTCs. If DTCs are displayed, go to appropriate DTC chart. See TROUBLE SHOOTING CHARTS.

STANDARD A/C SYSTEM RESPONSE (1)

DUAL ZONE A/C SYSTEM RESPONSE (1)

ECC TROUBLE SHOOTING CHART DIRECTORY

TROUBLE SHOOTING CHARTS

Note. Air Conditioning Programmer (ACP) may be referred as Air Conditioning Module (ACM), and Body Control Module (BCM) may be referred as Platform Zone Module (PZM) in troubleshooting charts.

CHART 1 - NO COMPRESSOR OPERATION

Compressor clutch coil receives power through A/C relay, and is grounded through circuit No. 250. Before diagnosing, ensure DTCs are corrected and cleared. An open power steering switch or faulty throttle position sensor could prevent A/C clutch engagement.

Note. Test numbers refer to numbers on diagnostic chart.

1. This step checks whether fault lies in output or input side of PCM.
2. This step checks A/C relay switch contacts.
3. This step checks if A/C relay is receiving power on circuit No. 2340.
4. This step checks if an open exists in compressor clutch power circuit No. 59.
5. This step checks if compressor clutch is faulty, or if an open exists in compressor clutch ground circuit No. 350.
6. This step checks A/C relay coil.
7. This step checks whether an open exists in circuit No. 603, 604 or 459.

Scheme 5

CHART 2 - NO BLOWER OPERATION OR IMPROPER BLOWER SPEED

Note. For revised procedure see Technical Service Bulletin 63-12-17 , dated December, 1996.

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

If blower is inoperative in normal operation, but operates properly in override, the IPC or data line between IPC and APC may be faulty.

Note. Test numbers refer to numbers on diagnostic chart.

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

Scheme 6

Scheme 7

CHART 3 - BLOWER ON CONTINUOUSLY

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

If blower is inoperative in normal operation, but operates properly in override, the IPC or data line between IPC and APC may be faulty.

Scheme 8

Scheme 9

Scheme 10

Scheme 11

CHART 5 - IMPROPER AIR DELIVERY

ACP will direct blended air in one of several air delivery modes. Side window outlets receive airflow during all modes of operation. ACP delivers airflow to other outlets by energizing specific vacuum valves, feeding appropriate mode valve actuator combination. ACP determines proper air delivery mode, based upon current program number, control panel setting, set temperature, low side temperature, coolant temperature, outside air temperature, and sunload.

Note. Test numbers refer to numbers on diagnostic chart.

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

Scheme 12

Scheme 13

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

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

Note. Test numbers refer to numbers on diagnostic chart.

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

Scheme 14

Scheme 15

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

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

Note. Test numbers refer to numbers on diagnostic chart.

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

Scheme 16

CHART 9 - REAR DEFOGGER ON CONTINUOUSLY

ACP provides ground for defogger relay when it receives a command from IPC via data line. IPC times operation initially for 10 minutes, and then commands programmer to deactivate relay ground. Additional requests for rear defogger are for 5-minute intervals until a new ignition cycle occurs. For information on grid repair, see appropriate REAR WINDOW DEFOGGERS article in ACCESSORIES & EQUIPMENT section.

Scheme 17

Scheme 18

CHART 10 - REAR DEFOGGER INOPERATIVE

ACP provides ground for defogger relay when it receives a command from IPC via data line. IPC times operation initially for 10 minutes, and then commands programmer to deactivate relay ground. Additional requests for rear defogger are for 5-minute intervals until a new ignition cycle occurs.

Scheme 19

DTC B1310 - OUTSIDE AIR TEMPERATURE SENSOR OPEN CIRCUIT

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

Test Conditions

Ignition on.

Failure Conditions

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

Actions Taken

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

Note On Intermittents

If an intermittent DTC B1310 is set, connect Tech 1, select ACP SNAPSHOT DATA for outside air temperature sensor, and note value. Manipulate related wiring while observing scan tester. If failure is induced, reading will jump. Check for poor terminal contact, obstructed sensor, or defective sensor.

Scheme 20

Scheme 21

DTC B1311 - OUTSIDE AIR TEMPERATURE SENSOR SHORT CIRCUIT

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

Ignition on.

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

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

If an intermittent DTC B1311 is set, connect Tech 1, select ACP SNAPSHOT DATA for outside air temperature sensor, and note value. Manipulate related wiring while observing scan tester. If failure is induced, reading will jump. Check for poor terminal contact, obstructed sensor, or defective sensor.

Scheme 22

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

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

1. Ignition on. DTC B1310 is not set.
2. Temperature is greater than 32°F (0°C).

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

On some vehicles, DTC may set intermittently if sensor temperature falls below 32°F (0°C). DTC becomes history after sensor temperature increases.

If an intermittent DTC B1312 is set, using Tech 1, select ACP SNAPSHOT DATA for high side temperature sensor, and note value. Manipulate related wiring while observing scan tester. If failure is induced, reading will jump. Check for poor terminal contact, obstructed sensor, or defective sensor.

Scheme 23

Scheme 24

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

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

1. Ignition on. DTC B1310 is not set.
2. Temperature is greater than 32°F (0°C).

1. High cooling fans operate when A/C compressor operation is possible.
2. A default value of 144°F (79°C) will be used to continue system operation.

Note. Test numbers refer to numbers on diagnostic chart.

1. Tech 1 displays high-side temperature. Jumpering harness connector will determine whether wiring or sensor is faulty.
2. Test light should not light. Test light is used to provide resistance.

On some vehicles, DTC may set intermittently if sensor temperature falls below 32°F (0°C). DTC becomes history after sensor temperature increases.

If an intermittent DTC B1313 is set, use Tech 1 to select ACP SNAPSHOT DATA for high side temperature sensor, and note value. Manipulate related wiring while observing scan tester. If failure is induced, reading will jump. Check for poor terminal contact, obstructed sensor, or defective sensor.

Scheme 25

ACP DTC B1314 - EVAPORATOR INLET TEMPERATURE SENSOR OPEN CIRCUIT

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

Ignition on.

1. A/C compressor clutch is not allowed to engage.
2. IPC displays SERVICE A/C SYSTEM - A/C COMPRESSOR OFF.
3. A default temperature reading of 43°F (6°C) will be implemented.

Note. Test numbers refer to numbers on diagnostic chart.

1. Tech 1 displays low-side temperature. Using jumper wire, connect harness connector to determine whether wiring or sensor is faulty.

If intermittent DTC B1314 is set, use Tech 1 to select ACP SNAPSHOT DATA for evaporator inlet temperature sensor, and note value.

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

Scheme 26

ACP DTC B1315 - EVAPORATOR INLET TEMPERATURE SENSOR SHORT CIRCUIT

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

1. Ignition on.

Actions Taken

1. A/C compressor clutch is not allowed to engage.
2. IPC displays SERVICE A/C SYSTEM - A/C COMPRESSOR OFF.
3. A default temperature reading of 43°F (6°C) will be implemented.

Note. Test numbers refer to numbers on diagnostic chart.

1. Tech 1 displays low-side temperature. Disconnecting harness connector will determine whether wiring or sensor is faulty.
2. Test light should not light. Test light is used to provide resistance.

If an intermittent DTC B1315 is set, use Tech 1 to select ACP SNAPSHOT DATA for evaporator inlet temperature sensor, and note value.

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

Scheme 27

ACP DTC B1316 - IN-CAR TEMPERATURE SENSOR OPEN CIRCUIT

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

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

1. A substitute temperature reading of 75°F (24°C) will be used to allow continued operation.

Note. Test numbers refer to numbers on diagnostic chart.

1. Tech 1 displays in-car temperature. Disconnecting harness connector will determine whether wiring or sensor is faulty.

If an intermittent DTC B1316 is set, use Tech 1 to select ACP SNAPSHOT DATA for in-car temperature sensor, and note value.

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

Scheme 28

ACP DTC B1317 - IN-CAR TEMPERATURE SENSOR SHORT CIRCUIT

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

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

1. A substitute temperature reading of 75°F (24°C) will be used to allow continued operation.

Note. Test numbers refer to numbers on diagnostic chart.

1. Tech 1 displays in-car temperature. Disconnecting harness connector will determine whether wiring or sensor is faulty.
2. Test light should not light. Test light is used to provide resistance.

If an intermittent DTC B1317 is set, use Tech 1 to select ACP SNAPSHOT DATA for in-car temperature sensor and note value. Manipulate related wiring while observing scan tester. If failure is induced, reading will jump. Check for poor terminal contact, obstructed sensor, or defective sensor.

Scheme 29

ACP DTC B1318 - SUNLOAD SENSOR OPEN CIRCUIT

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

Ignition on.

1. A substitute reading of 250 counts will be implemented to allow continued operation of system.

Note. Test numbers refer to numbers on diagnostic chart.

1. Tech 1 displays sunload reading. Disconnecting harness connector will determine whether wiring or sensor is faulty.

If an intermittent DTC B1318 is set, use Tech 1 to select ACP SNAPSHOT DATA for sunload sensor, and note value.

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

Scheme 30

ACP DTC B1319 - SUNLOAD SENSOR SHORT CIRCUIT

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

Ignition on.

1. A substitute reading of 250 counts will be implemented to allow continued operation of system.

Note. Test numbers refer to numbers on diagnostic chart.

1. Tech 1 displays sunload reading. Disconnecting harness connector will determine whether wiring or sensor is faulty.
2. Test light should not light. Test light is used to provide resistance.

If an intermittent DTC B1319 is set, use Tech 1 to select ACP SNAPSHOT DATA for sunload sensor and note value.

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

Scheme 31

ACP DTC B1340 - AIR-MIX DOOR NO. 1 CIRCUIT PROBLEM

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

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

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

None.

Note. Test numbers refer to numbers on diagnostic chart.

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

If an intermittent DTC B1340 is set, use Tech 1 to select ACP SNAPSHOT DATA for air-mix door No. 1, and note value. Using Tech 1, override while monitoring feedback value, command door to these positions. Without turning ignition off, physically inspect mix door linkage for any obstruction at these positions.

Scheme 32

Scheme 33

ACP DTC B1341 - AIR-MIX DOOR NO. 2 CIRCUIT PROBLEM

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

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

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

None.

Note. Test numbers refer to numbers on diagnostic chart.

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

If an intermittent DTC B1341 is set, use Tech 1 to select ACP SNAPSHOT DATA for air-mix door No. 2, and note value. Using Tech 1 override, while monitoring feedback value, command door to these positions. Without turning ignition off, physically inspect mix door linkage for any obstruction at these positions.

Scheme 34

ACP DTC B1347 - VERY LOW A/C REFRIGERANT WARNING

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

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

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

1. Disables A/C compressor until DTC is cleared.
2. Displays VERY LOW A/C REFRIGERANT - A/C COMPRESSOR OFF message on Driver Information Center (DIC).

Note. Test numbers refer to numbers on diagnostic chart.

1. Checks for intermittent open or short in pressure switch circuit.
2. Checks for restriction within refrigerant system.
3. An offset in ACP temperature sensor's actual outside or low-side may trigger a false DTC. After leaving vehicle, preferably overnight, in a shaded, cold environment, enter diagnostics without starting engine. All listed sensor readings should agree within 4°F (2°C).
4. Recover and recharge system

REFRIGERANT TEMPERATURE TO PRESSURE CONVERSION

Scheme 35

ACP DTC B1348 - VERY LOW A/C REFRIGERANT PRESSURE

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

Low refrigerant pressure switch remains open for several minutes.

1. Disables A/C compressor until DTC is cleared.
2. Display VERY LOW A/C REFRIGERANT - A/C COMPRESSOR OFF message on Driver Information Center (DIC).

Note. Test numbers refer to numbers on diagnostic chart.

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

REFRIGERANT TEMPERATURE TO PRESSURE CONVERSION

Scheme 36

Scheme 37

ACP DTC B1350 - ENGINE COOLANT TEMPERATURE TOO HIGH

DTC B1350 is designed to disengage A/C compressor clutch if coolant temperature exceeds 258°F (126°C). Once code has been set, it will remain current until coolant temperature falls below 244°F (116°C). ACP receives coolant temperature information from PCM over serial data. While DTC B1350 is current, IPC will display ENGINE HOT - A/C COMPRESSOR OFF warning on DIC.

Scheme 38

ACP DTC B2024 - LOSS OF PCM SERIAL DATA

DTC B2024 will set if ignition is on and ACP has lost data communication with PCM. Diagnosis of this DTC is dependent upon other system symptoms (DTCs) present with DTC B2024.

Ignition on.

Open Circuit.

Action Taken

Set DTC B2024.

Troubleshooting Hints

1. Using Tech 1, attempt to establish communications with PCM.
2. Check circuit No. 1807 for an open or short to power or ground.
3. Ensure PCM is connected to power and ground.
4. If multiple Class 2 DTCs are current, check circuit No. 1807 for short to ground or voltage. See MULTIPLE DATA COMMUNICATIONS CODES chart in appropriate article in ACCESSORIES & EQUIPMENT section.
5. Ensure PCM is operating properly. See appropriate article in ENGINE PERFORMANCE section.
6. DTC P1605 (PCM loss of HVAC serial data) may be present with this DTC. This indicates PCM and ACP were functional when DTC was set, but could not communicate with each other. Refer to appropriate article in ENGINE PERFORMANCE section.

Scheme 39

ACP DTC B2064 - LOSS OF PZM SERIAL DATA

DTC B2064 will set if ignition is on and ACP has lost data communication with PZM. Diagnosis of this code is dependent upon other system symptoms (DTCs) present with DTC B2064.

Ignition on.

Open Circuit.

Set DTC B2064.

1. Using Tech 1, attempt to establish communications with PZM.
2. Check circuit No. 1807 for an open or short to power or ground.
3. Ensure PZM is connected to power and ground.
4. DTC PZ2152 (loss of ACP serial data) may be present with this DTC. This indicates PZM and ACP were functional when DTC was set, but could not communicate with each other. Refer to appropriate article in the ACCESSORIES/SAFETY EQUIPMENT section.
5. If multiple Class 2 DTCs are current, check circuit No. 1807 for short to ground or voltage. See MULTIPLE DATA COMMUNICATIONS CODES chart in appropriate article in ACCESSORIES & EQUIPMENT section.
6. Ensure PZM is operating properly. See appropriate article in ACCESSORIES & EQUIPMENT section.

ACP DTC B2096 - LOSS OF IPC SERIAL DATA

DTC B2096 will set if ignition is on and ACP has lost data communication with IPC. This DTC should be seen only as a history DTC. If communications are currently inoperative, ACP will not be able to communicate with IPC to display DTC. Diagnosis of this code is dependent upon other system symptoms (DTCs) present with DTC B2096.

Ignition on.

Open Circuit.

Set DTC B2096.

1. Using Tech 1, attempt to establish communications with IPC.
2. Check circuit No. 1807 for an open or short to power or ground.
3. Ensure PZM is connected to power and ground.
4. DTC IP2152 (loss of ACP serial data) may be present with this DTC. This indicates PZM and ACP were functional when DTC was set, but could not communicate with each other. Refer to appropriate article in ACCESSORIES/SAFETY EQUIPMENT section.
5. If multiple Class 2 DTCs are current, check circuit No. 1807 for short to ground or voltage. See MULTIPLE DATA COMMUNICATIONS CODES chart in appropriate article in ACCESSORIES & EQUIPMENT section.

ACP DTC B2153 - LOSS OF CCP SERIAL DATA

DTC B2153 will set if ignition is on and ACP has lost data communication with CCP. Diagnosis of this DTC is dependent upon other system symptoms (DTCs) present with DTC B2153.

Ignition on.

Open Circuit.

Set DTC B2153.

1. Using Tech 1, attempt to establish communications with CCP.
2. Check circuit No. 1807 for an open or short to power or ground.
3. Ensure CCP is connected to power and ground.
4. DTC CC2152 (loss of ACP serial data) may be present with this DTC. This indicates CCP and ACP were functional when DTC was set, but could not communicate with each other. See appropriate article in ACCESSORIES & EQUIPMENT section.
5. If multiple Class 2 DTCs are current, check circuit No. 1807 for short to ground or voltage. See MULTIPLE DATA COMMUNICATIONS CODES chart in appropriate article in ACCESSORIES & EQUIPMENT section.

TESTING

Note. DTCs may be viewed or cleared using self-diagnostics or Tech 1 scan tester. Tech 1 scan tester is required to perform tests or overrides.

A/C SYSTEM PERFORMANCE

1. Park vehicle in shaded area. Ventilate interior. Vent exhaust. Install gauge set. Measure and record ambient temperature and relative humidity. Close doors and windows. Set controls to AUTO, select maximum blower speed, and set temperature control to coldest value. Insert thermometer into center outlet.
2. Set transmission in Park or Neutral. Start and idle engine for 10 minutes. Record outlet temperature, and high side and low side pressures. Turn engine off. Compare readings with specifications. See A/C PERFORMANCE SPECIFICATIONS table.

A/C PERFORMANCE SPECIFICATIONS

ACP SELF-DIAGNOSTICS

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

Fault Detection

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

Note. Self-diagnostics for 11 computer-controlled systems are available. Only information relating to A/C self-diagnostics is given.

Entering Self-Diagnostics

To enter self-diagnostics, turn ignition on with engine off. Simultaneously press OFF button and WARM button (standard A/C system), or OFF button and PASSENGER WARMER button (dual zone A/C system) on climate control center. (Scheme 1)or (Scheme 2). Hold buttons until a segment check is displayed. This should take about 3 seconds. If any segments do not light, replace display.

Displaying ACP Diagnostic Trouble Codes (DTCs)

Press fan LO (down arrow) until ACM is displayed. Press fan HI (up arrow) until ACM CODES? is displayed. Press fan HI (up arrow) again; any stored ACP DTCs will be displayed. See ACP DIAGNOSTIC TROUBLE CODES table. A "C" or "H" at end of DTC indicates whether DTC is current (fault still exists) or historical (failure occurred during one of last 50 ignition cycles).

Clearing ACP DTCs

Enter self diagnostics. See ENTERING SELF-DIAGNOSTICS. Press fan LO (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.

Exiting Self-Diagnostics

To exit self-diagnostics, press MODE or DEFOG button, or turn ignition off. DTCs are not cleared when exiting self-diagnostics.

Note. System returns to mode it was in before it entered self-diagnostics.

If DTCs do not exist in memory for ACP, a NO AC CODES message will be displayed. If IPC cannot communicate with ACP, a NO AC DATA message will be displayed. To repair affected circuit, see TROUBLE SHOOTING CHARTS.

ACP DIAGNOSTIC TROUBLE CODES

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

REMOVAL & INSTALLATION

Disconnect negative battery cable. Remove right sound insulator. Remove glove box. See GLOVE BOX. Unplug programmer electrical and vacuum connectors. Remove programmer. (Scheme 3) To ins tall, 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. To install, reverse removal procedure. Evacuate and recharge A/C system.

AIR-MIX VALVE ACTUATOR(S)

Note. If an actuator has been replaced, actuator need to be recalibrated for proper travel. To recalibrate actuator, cycle ignition switch to ON position for 3 minutes.

Remove glove box. See GLOVE BOX. Unsnap rod from plastic retainer on actuator arm. Remove actuator mounting screws. Unplug electrical connector. Remove actuator. Check air-mix door for free travel. To install, reverse removal procedure.

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

Removal

1. Disconnect negative battery cable. Remove cross-tower brace. Unplug 4 ignition control module electrical connectors. Position cross car harness aside. Unplug No. 5 and 7 spark plug wires. Position spark plug harness aside. Unplug 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. Unplug wiring connector from blower motor. Remove 5 blower motor mounting screws. Rotate blower motor until flat side is down. (Scheme 40) 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 40)
2. Install inertia plate and screws. Install blower motor screws and tighten to 7 INCH lbs. (1 N.m). To complete installation, reverse removal procedures.

Scheme 40

1. Disconnect negative battery cable. Discharge A/C system using approved refrigerant recovery/recycling equipment. Disengage drive belt. Raise and support vehicle. Remove right wheel. Remove compressor splash shield. Remove engine splash shield and retainer.
2. Remove oil filter. Disconnect oil cooler lines from oil filter adapter. Unplug electrical connections from compressor. Remove compressor line fitting bolt. Remove compressor from mounting bracket. To install, reverse removal procedure. Evacuate and recharge A/C system.

1. Disconnect negative battery cable. Discharge A/C system using approved refrigerant recovery/recycling equipment. Remove SIR discriminating sensor. Remove engine torque struts. Remove right and left cooling fans. Remove radiator top support bracket. Tilt radiator/condenser assembly rearward. Disconnect pressure fittings. Cap all openings.
2. Remove condenser-to-radiator screws. Remove condenser. To install, reverse removal procedure. Evacuate and recharge 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. Unplug vacuum and electrical connectors. Remove powertrain control module. Remove programmer. See A/C PROGRAMMER.
2. Loosen instrument panel brace. Remove bolt securing evaporator core housing to front of dash board. Bolt is located above carpet, directly behind left side of console. Remove heater core. Remove cross car brace. Remove evaporator/accumulator lines.
3. Remove 2 bolts securing wiring harness pass-through to front of dashboard. Unplug electrical connectors from ignition control module, blower motor, rear O2 sensor, A/C high and low-side temperature sensors, HVAC module, and A/C low pressure switch.
4. Remove ignition control module, air cleaner, and PCV valve. Remove coolant by-pass hose from coolant recovery tank. Remove left side radiator support and radiator shroud. Unplug electrical connectors from park/neutral position switch, MAP sensor, and cruise control servo. Release wiring harness from body.
5. Disconnect brake booster hose. Remove left and right engine struts and bracket. 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.
6. Remove radiator, transmission, and left wheelwell splash shields. Remove ABS unit from cradle bracket. Unplug electrical connectors at power steering pressure switch, vehicle speed sensor, knock sensor, and engine ground wire. Remove exhaust pipe at catalytic converter. Remove left and right brake calipers.
7. Remove left and right vehicle speed sensors from body. 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. 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. To install, reverse removal procedure. Evacuate and recharge A/C system.

Open trap door in rear of glove compartment. Disconnect passenger-side air bag module wiring connector from retaining clip on rear of glove box. Remove glove compartment light lens by gently prying release tabs. Gently pry top of switch cover to release tab. Reaching through light opening, push switch outboard. Unplug 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. Remove right lower sound insulator. Unplug electrical connectors. Remove programmer. See A/C PROGRAMMER.
2. Remove heater core cover. Remove inlet and outlet hoses from heater core. Remove 2 heater core retaining screws. Remove heater core. To install, reverse removal procedure. Fill cooling system. Perform air-mix valve adjustment. See AIR-MIX VALVE under ADJUSTMENTS.

HIGH PRESSURE SWITCH

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

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

LOW PRESSURE SWITCH

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

Disconnect negative battery cable. Unplug 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. Unplug outside temperature sensor connector. Remove sensor. To install, reverse removal procedure.

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

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

TORQUE SPECIFICATIONS

TORQUE SPECIFICATIONS

Scheme 41

Scheme 42

Automatic A/C-Heater System Wiring Diagram (1 Of 2). Scheme 43

Automatic A/C-Heater System Wiring Diagram (2 Of 2). Scheme 44