Automatic A/c-Heater Systems: Other Jaguar XKR I

AUTOMATIC CLIMATE CONTROL SYSTEM

Climate control system is a fully automatic temperature controlled heating and air conditioning system. Management of system is through a control panel allowing full automatic control of selected temperature within a 62-88°F (17-31°C) range, or by manual override control of temperature, blower speeds and air distribution. (Scheme 4)

Scheme 4

A/C COMPRESSOR

A compressor on signal is monitored from compressor relay to inform A/C Control Module (A/CCM) of compressor status. Compressor rotating signal is generated at compressor and then compared with engine speed. If speed is excessive, compressor clutch will disengage and LED on control panel will flash. Refrigerant pressure is monitored by a pressure (bitron) switch located in discharge line. Monitored pressures are used by ECM to disengage compressor clutch drive and control cooling fan operation based on refrigerant pressures. Compressor is protected from excessively high pressures by a high-pressure relief valve, incorporated into compressor.

A/C CONTROL MODULE

A/C Control Module (A/CCM) is located on right side of A/C unit and controls all climate control system functions. Temperature within vehicle is continually compared with temperature selected on control panel. A/CCM receives data input signals and compares these with signals from system temperature sensors and feedback devices. Based on this information A/CCM adjusts air outlet temperature, airflow and distribution from A/C system into vehicle.

A/C-HEATER SYSTEM CONTROL PANEL

Note. When buttons with an integral LED are pushed, LED will illuminate confirming function activation. One or 2 beeps will accompany LED to confirm function selection. (Scheme 4)

Switching Climate Control System On

Climate control system can be turned on by pressing one of following buttons

1. System and fan on/off turns system on in a previous settings.
2. A/C turns system on in previous settings.
3. AUTO turns system on at previous temperature setting.
4. DEF turns system on at previous temperature setting.

System & Fan On/Off (Manual Fan Speed)

Pressing this knob turns system on at last setting or turns system off. Rotating knob clockwise increases fan speed. Rotating knob counterclockwise decreases fan speed. With system off, ram air is available by selected air distribution mode. Airflow does not occur unless a manual air distribution mode is selected, is not conditioned and is dependent on vehicle speed. Fan operation is inhibited until engine coolant temperature is more than 95°F (35°C), unless DEF (defrost) is selected.

Manual Air Recirculation

Pressing recirculation button closes outside air intakes and recirculates air within vehicle. When button is pressed for less than 1.5 seconds, LED will illuminate and a beep will sound confirming activation. Recirculation will operate for about 5 minutes. Pressing button within 5 minutes will return system to fresh air intake mode. When button is pressed for more than 1.5 seconds, LED will illuminate and 2 beeps will sound confirming activation. Recirculation will operate continuously. Pressing button again will return system to fresh air intake mode. Using manual air recirculation for prolonged periods in cold weather, may result in interior misting of glass.

External Ambient Temperature Display

When EXT button is pressed for less than 1.5 seconds, LED will illuminate and a beep will sound confirming quick display activation. External ambient air temperature will display for 4 seconds. When EXT button is pressed for more than 1.5 seconds, LED will illuminate and 2 beeps will sound confirming continuous display activation. Temperature value will be updated every 4 seconds when vehicle speed is more than 16 MPH. Continuous temperature display will be cancelled when ignition is turned off, but not during engine cranking.

A/C button will either select or deselect A/C compressor operation. When button is pressed, LED will illuminate confirming A/C compressor operation request.

When AUTO button is pressed, LED will illuminate, A/C mode will be operational and control of vent outlet temperature, speed of fans and air distribution will be controlled automatically. AUTO mode will be deactivated when manual air distribution or defrost buttons are pressed or manual fan speed knob is rotated. Automatic temperature control is constantly maintained irrespective of selected manual overrides.

Defrost

When DEF (defrost) button is pressed, air will be directed to front and side glass at maximum fan speed. Heated windshield (if equipped) will be energized for about 6.5 minutes. Pressing DEF again will return to last setting with automatic temperature control being maintained. Directing warm, humid air onto a cold windshield can cause interior misting. Directing cold air onto windshield in warm humid conditions can cause external condensation.

Heated Windshield

Pressing heated windshield "F" button (if equipped) will energize electrically heated windshield elements for a 6.5 minute timed cycle. Pressing button again will cancel heated windshield request. Heated windshield can be activated with climate control system off, if engine is operating. If engine stalls or ignition is turned off, timer will be cleared and function cancelled. In very cold ambient temperatures, icing of interior glass is possible when climate control system is operating in AUTO mode. A/CCM will activate heated windshield when external temperature is less than 32°F (0°C) and vehicle speed is more than 30 MPH for at least 2 minutes and engine speed is more than 50 RPM. When windshield is energized, LED will not be illuminated.

Heated Rear Screen

Pressing heated rear screen "R" button will simultaneously energize heated rear screen elements for a 21 minute timed cycle and heated exterior mirror elements for an 11 minute timed cycle. Pressing button again within 21 minute timed cycled will cancel request. If engine stalled or ignition turned off, rear screen and door mirror timers will be cleared and functions cancelled. Heated rear window function can be activated with climate control system off, if engine is operating.

Temperature Control

Pressing temperature control button (down arrow) decreases interior temperature setting in one degree increments. If button is pressed when set temperature is less than lowest automatic control temperature limit, display will indicate LO. When LO is selected, climate control system operates at maximum cooling performance with fans operating automatically at maximum speed. Pressing temperature control button (up arrow) increases interior temperature setting in one degree increments. If button is pressed when set temperature is more than upper automatic control temperature limit, display will indicate HI. When HI is selected, climate control system operates at maximum heating performance with fans operating automatically at maximum speed. Selected temperature range is 61-90°F (17-31°C). Pressing and holding either temperature control button continuously changes temperature setting in steps of one degree, every 0.4 seconds.

Face

Pressing face level button will direct all airflow to center and side face vents only; pressing button again will return climate control system to automatic control mode. In AUTO mode and a hot climate, a bleed of cold air is delivered to foot level. This bleed automatically shuts off when interior temperature has cooled sufficiently.

Bi-Level

Pressing bi-level button will direct air to center and side face vents and front footwells. Pressing button (off) will return climate control system to automatic control mode.

Foot

This button will direct majority of airflow to front footwells with a small bleed of air to front and side screens. Pressing button (off) will return climate control system to automatic control mode.

Demist

Pressing this button will direct air to the front and side screens and the front footwells. Pressing the button (off) will return the system to automatic control mode.

Fascia (Center) Air Outlets

Center vent assembly incorporates face vent temperature control thumbwheel. This control provides outlet air temperature adjustment from center and end of dash vents, relative to foot duct air temperature. Air temperature from face vents air will increase when thumbwheel is rotated upward and decrease when rotated downward. Face level air temperature is always cooler than foot air temperature and temperature differential control only operates when climate control system is in AUTO or manual bi-level mode.

A/C CONTROL

In-vehicle temperature is maintained at level selected on control panel by A/CCM. Module is mounted on side of A/C unit case. (Scheme 5) Control module receives and computes signals input from a number of switches and sensors and provides required power outputs to drive servos, blowers, valves and windshield/mirror heaters. ECM interfaces with A/CCM to control operation of A/C compressor. ECM de-energizes compressor relay when engine temperatures or acceleration require a reduction in engine load.

Scheme 5

AIR DISTRIBUTION

Airflow distribution system includes connecting ducts between blowers and A/C unit, front footwell ducts and instrument panel ducts. Integral with fascia trim is front and side glass defrost ducting. Air conditioning and heater unit is located centrally behind fascia. Air intake plenum houses an optional particle filter held in place by clips molded on filter housing.

Airflow is achieved using blower units located on each side of A/C unit case. Two blower motors are controlled at variable speeds by A/CCM. Blower motors do not operate when engine coolant temperature is less than 86°F (30°C). Air flows through the vehicle to the trunk, venting under each rear fender.

AIR CONDITIONING UNIT

A/C unit case incorporates two servo motors which change air flap position. Servo motor position is monitored by a feedback potentiometer in each motor housing.

SERVO MOTOR CONTROL

Flap position, which directs flow of air through system, is controlled by servo motors. Servo motors may be driven in either a clockwise or counterclockwise direction by signals from A/CCM. Flap position is monitored via a feedback potentiometer which is located in motor housing. Servo motors control right and left air intake (fresh/recirculated air), center vent, defrost, foot and cool air by-pass.

BLOWER MOTOR CONTROL

A/CCM controls speed of both blower motors used to deliver airflow to air conditioning unit. Blower motors are regulated by power transistor modules which provide a linear variation of blower speed.

CONDENSER

Condenser is a multi-pass conventional fin/tube design of lightweight construction. Condenser is mounted in front of radiator.

ENGINE CONTROL MODULE (ECM)

ECM provides a signal to A/CCM to disengage blower function when engine coolant temperature is less than 86°F (30°C). This input also monitors coolant temperature to heater core to assist in heater outlet temperature control.

EXPANSION VALVE

Expansion valve is located inside A/C unit and comprises of a diaphragm, connected by a capillary tube to a temperature sensing bulb, which regulates the valve according to temperature variations at the evaporator outlet pipe.

HEATING SYSTEM

Hot water is supplied from engine cooling system via a solenoid-operated control valve and circulated by an electric pump. Pump is operated in all engine running modes except low coolant temperature or off mode. Pump is off with ignition on and engine not running. Control valve is located next to heater water pump.

HIGH PRESSURE RELIEF VALVE

High-pressure relief valve, is used to avoid system overpressure. High-pressure relief valve is located in A/C compressor. Valve will open, and release pressure when system pressure is more than 595 psi (41.8 kg/cm 2 ). Valve will reseat when system pressure decreases to less than 400 psi (28.1 kg/cm 2 ).

REFRIGERANT PRESSURE (BITRON) SWITCH

Pressure switch is located in discharge pipe. Pressure switch provides a signal, via A/CCM, to ECM, to disengage compressor clutch. Compressor clutch will be disengaged when system refrigerant pressure is less than 29.0 psi (2.0 kg/cm 2 ) or more than 435.1 psi (30.6 kg/cm 2 ).

Pressure switch provides a hard-wired signal to ECM, for cooling fan control, based on A/C system pressure. ECM will switch cooling fans to high speed when pressure is 319.1 psi (22.4 kg/cm 2 ) and increasing, and to low speed when pressure is 253.8 psi (17.8 kg/cm 2 ) and decreasing. ECM will switch cooling fans to low speed when pressure is 174.0 psi (12.2 kg/cm 2 ) and increasing, and off when pressure is 116.0 psi (8.2 kg/cm 2 ) and decreasing.

RECEIVER-DRIER

Receiver-drier is mounted next to radiator on right of engine compartment, and has a high-side charge port. Low-side charging port is in suction hose next to bulkhead.

Ambient Temperature Sensor

Ambient temperature sensor is mounted on right horn bracket. (Scheme 6) Sensor provides an ambient air temperature signal to A/CCM which compensates for ambient conditions and also provides signal for control panel ambient temperature display. Temperature displayed is updated every 4 seconds. Sensor response is dampened by A/CCM to slow changes in temperature to prevent effects of sudden changes in air outlet temperatures.

Scheme 6

Engine Coolant Temperature Sensor

Engine Coolant Temperature (ECT) sensor signal is supplied to A/CCM from instrument cluster. A/CCM uses signal to provide blower inhibit control in heating mode, to avoid delivering cold air when coolant temperature is less than 95°F (35°C) unless DEF is selected. Fan speed is progressively increased up to maximum blower speed during warm up control, to assist in the control of the outlet temperature, and to avoid possible pump or valve damage caused by ice particles in coolant.

Evaporator Temperature Sensor

Evaporator temperature sensor is located next to evaporator. Sensor provides signals to A/CCM which disengages compressor when outlet temperature is 36°F (2°C) or less to prevent evaporator freeze-up. When evaporator air outlet temperature is 37°F (3°C) or more, A/CCM signals ECM to engage compressor.

Heater Matrix Temperature Sensor

Heater matrix (heater core) temperature sensor is installed inside heater case and measures post-heater air temperature. Sensor connector is located on right side of air conditioning unit. Sensor provides a signal to A/CCM which adjusts water valve duty ratio to provide required air temperature from heater.

In-Vehicle Temperature Sensor

In-vehicle temperature sensor is located inside motorized in-vehicle aspirator. Temperature sensor signal is sent to A/CCM and used to adjust temperature, airflow and air distribution from air conditioning unit.

Sunlight Load (Solar) Sensor

Solar sensor is mounted on top of instrument panel between the driver's defrost vent and speaker grille. (Scheme 7) Sensor is a photodiode, calibrated to measure direct sunlight load. Sensor provides an output signal to A/CCM which automatically reduces air temperature and increases fan speed (airflow volume) to compensate for solar heating.

Scheme 7

FUNCTIONAL CHECK

Note. All mode buttons should illuminate when pressed.

Start engine and warm to normal operating temperature.

1. Press AUTO (selected temperature, AUTO and A/C lights should illuminate).
2. Rotate fan knob to increase or decrease fan speed (bar graph should increase or decrease).
3. Ensure ambient air temperature is more than 36°F (2°C) and engine coolant temperature is normal. If ambient air temperature is less than 36°F (2°C) or engine coolant temperature is not normal ECM will inhibit compressor operation. Toggle A/C button on and off (A/C compressor clutch should cycle on and off).
4. Push recirculated air button (button illuminates and flap behind blower grille opens).
5. Push different air distribution buttons (button illuminates and air flows out of appropriate vents).
6. Push DEF (button illuminates, both blower fans engage at high speed and air flows to front windshield).
7. Cycle temperature buttons from HI to LO (maximum heat or cold, independent of in-vehicle temperature).
8. Push EXT button (display should toggle between outside and desired temperature).
9. Push heated front (if equipped) and rear window (note timer and mirror operation by checking for warm class).
10. Perform system self-diagnostic test if any control panel button does not operate as stated. See «RETRIEVING DIAGNOSTIC TROUBLE CODES»(ref-12062-S14374194222000120700000) .

A/C-HEATER CONTROL PANEL CHECK

The A/C-heater control panel check verifies inputs and outputs between A/C-heater control panel and A/CCM. While holding down face vent mode and fan switch buttons, turn ignition to ON position. See A/C-HEATER PANEL COMMUNICATIONS table to match appropriate circuit to light. If any of listed lights are not glowing, that circuit failed A/C-heater panel communications line test. To exit A/C-heater control panel check, turn A/C system on.

A/C-HEATER PANEL COMMUNICATIONS

ACTUATOR CHECK

Note. System self-test procedure drives all actuator motors, to check their operation. If an actuator is operating incorrectly or operating outside of its limits a fault code will set.

1. Ensure vehicle is operating under normal conditions. Turn ignition off. Press and hold recirculated air and AUTO buttons simultaneously. (Scheme 4) Turn ignition on and start engine.
2. All control panel LEDs and all LCD segments will flash on and off. Any function LED indicator that does not flash on and off indicates a related fault or, with LED. Any LCD element which fails to flash on and off indicates a fault within display element or panel.
3. Press AUTO button. Press recirculated air button to start actuator check mode. Press face button to cycle through actuator mode conditions 20 through 27. (Scheme 8) Press fan button to restore normal operation with default panel settings.

Scheme 8

Note. A/CCM cuts off blower motor voltage if heating is selected when coolant temperature is less than 95°F (35°C) unless defrost/demist is selected.

A/CCM controls speed of both blower motors. Blower motors are regulated by power transistor modules which provide a linear variation of blower speed. See BLOWER CONTROL SPEED/VOLTAGE RELATIONSHIP table. Monitor voltage at blower motors. See WIRING DIAGRAMS .

BLOWER CONTROL SPEED/VOLTAGE RELATIONSHIP

NO COOLING

Check electrical circuit to compressor clutch and/or electrical circuits to blower motors. Loose or broken belt. A/C compressor binding or seizure. A/C compressor shaft seal leak, system leak, broken or leaking hose (DTC 23). Blocked or restricted filter in receiver-drier. Evaporator sensor disconnected (DTC 13). Defective pressure switch (DTC 23).

INSUFFICIENT COOLING

Look for sluggish blower motors. Restricted blower inlet or outlet. Blocked or restricted condenser, evaporator or filter (in receiver-drier or expansion valve). Collapsed flexible pipe. Expansion valve temperature sensor. Excessive moisture or air in system. Low refrigerant charge (DTC 23). Slipping A/C compressor clutch. Air distribution vents or flaps closed or seized (DTC 41 and 46). Heater coolant flow always open. Evaporator sensor positioned incorrectly.

INTERMITTENT COOLING

Intermittent voltage to compressor clutch. Intermittent voltage to blower motors. Slipping A/C compressor clutch. Motorized in-vehicle aspirator or evaporator sensor faulty (DTC 11 or 13). Blocked or restricted condenser or evaporator.

INSUFFICIENT HEATING

Heater valve stuck closed. Motorized in-vehicle aspirator seized. Cool air by-pass damper stuck or seized (DTC 43). Blocked or restricted blower inlet or outlet. Low coolant level. Blower fan speed too low. Thermostat seized open or defective. Heater pump defective or blocked. Air lock in cooling system.

NOISY SYSTEM

Loose or broken belt. Loose or broken A/C compressor mountings. Low A/C compressor oil level (leak). A/C compressor binding or seizure. Blower motors noisy. Vibration or thumping in high-pressure line (high refrigerant pressure). Hissing at expansion valve (low refrigerant pressure). Moisture in system (expansion valve noise). Heater pump air lock.

Possible Cause

Check wiring harness for an open, short or high resistance in vehicle speed input circuit between ECM and A/CCM. See WIRING DIAGRAMS . Repair or replace as necessary.

Check wiring harness for an open, high resistance or short to battery voltage. See WIRING DIAGRAMS . Repair or replace as necessary.

Check wiring harness for a short to ground. See WIRING DIAGRAMS . Repair or replace as necessary.

Check wiring harness for open circuit, high resistance or a short to battery voltage. See WIRING DIAGRAMS . Repair or replace as necessary

Check wiring harness for a short to ground. See WIRING DIAGRAMS . Repair or replace as necessary.

Check wiring harness for open circuit, high resistance or a short to battery voltage. See WIRING DIAGRAMS . Repair or replace as necessary

Check wiring harness for a short to ground. See WIRING DIAGRAMS . Repair or replace as necessary.

Check defrost vent servo motor drive circuit for an open, short or high resistance. See WIRING DIAGRAMS . Check servo motor operation. Repair or replace as necessary.

Check center vent servo motor drive circuit for an open, short or high resistance. See WIRING DIAGRAMS . Check servo motor operation. Repair or replace as necessary.

Check foot vent servo motor drive circuit for an open, short or high resistance. See WIRING DIAGRAMS . Check servo motor operation. Repair or replace as necessary.

Check cool air by-pass servo motor drive circuit for an open, short or high resistance. See WIRING DIAGRAMS . Check servo motor operation. Repair or replace as necessary.

Check left fresh/recirculated air servo motor drive circuit for an open, short or high resistance. See WIRING DIAGRAMS . Check servo motor operation. Repair or replace as necessary.

Check right fresh/recirculated air servo motor drive circuit for an open, short or high resistance. See WIRING DIAGRAMS . Check servo motor operation. Repair or replace as necessary.

Check defrost feedback potentiometer sensor circuit for an open, high resistance or a short to battery voltage. See WIRING DIAGRAMS . Repair or replace as necessary.

Check defrost feedback potentiometer sensor circuit for a short to ground. See WIRING DIAGRAMS . Repair or replace as necessary.

Check center vent feedback potentiometer sensor circuit for an open, high resistance or a short to battery voltage. See WIRING DIAGRAMS . Repair or replace as necessary.

Check center vent feedback potentiometer sensor circuit for a short to ground. See WIRING DIAGRAMS . Repair or replace as necessary.

Check foot vent feedback potentiometer sensor circuit for an open, high resistance or a short to battery voltage. See WIRING DIAGRAMS . Repair or replace as necessary.

Check foot vent feedback potentiometer sensor circuit for a short to ground. See WIRING DIAGRAMS . Repair or replace as necessary.

Check cool air by-pass feedback potentiometer sensor circuit for an open, high resistance or a short to battery voltage. See WIRING DIAGRAMS . Repair or replace as necessary.

Check cool air by-pass feedback potentiometer sensor circuit for a short to ground. See WIRING DIAGRAMS . Repair or replace as necessary.

Check left fresh/recirculated air feedback potentiometer sensor circuit for an open, high resistance or a short to battery voltage. See WIRING DIAGRAMS . Repair or replace as necessary.

Check left fresh/recirculated air feedback potentiometer sensor circuit for a short to ground. See WIRING DIAGRAMS . Repair or replace as necessary.

Check right fresh/recirculated air feedback potentiometer sensor circuit for an open, high resistance or a short to battery voltage. See WIRING DIAGRAMS . Repair or replace as necessary.

Check right fresh/recirculated air feedback potentiometer sensor circuit for a short to ground. See WIRING DIAGRAMS . Repair or replace as necessary.

Check battery voltage supply circuit for an open or high resistance. See WIRING DIAGRAMS . Repair or replace as necessary.

Check battery voltage supply circuit for a short to ground. See WIRING DIAGRAMS . Repair or replace as necessary.

Check sensor 5-volt reference voltage supply circuit for an open or a short to battery voltage. See WIRING DIAGRAMS . Repair or replace as necessary.

Check sensor 5-volt reference voltage supply circuit for a short to ground. See WIRING DIAGRAMS . Repair or replace as necessary.

Check sensor 5-volt reference voltage supply circuit for high resistance. See WIRING DIAGRAMS . Repair or replace as necessary.

Check battery voltage supply circuit for an open or short to ground. See WIRING DIAGRAMS . Repair or replace as necessary.

Check face vent differential temperature control potentiometer circuit for an open, high resistance or a short to battery voltage. See WIRING DIAGRAMS . Repair or replace as necessary.

Check face vent differential temperature control potentiometer circuit for a short to ground. See WIRING DIAGRAMS . Repair or replace as necessary.

Check aspirator motor circuit for an open or high resistance. Check aspirator motor operation. See WIRING DIAGRAMS . Repair or replace as necessary.

Check aspirator motor circuit for a short to ground. See WIRING DIAGRAMS . Repair or replace as necessary.

Check ignition switched ground signal circuit for an open or high resistance. See WIRING DIAGRAMS . Repair or replace as necessary.

Check system refrigerant charge. Check refrigerant pressure switch circuit for an open, high resistance or a short to battery voltage. Check for high engine temperature in high ambient air temperatures. See WIRING DIAGRAMS . Repair or replace as necessary.

Check refrigerant pressure switch circuit for a short to ground. See WIRING DIAGRAMS . Repair or replace as necessary.

Check compressor drive belt condition and adjustment. Check compressor lock, compressor lock sensor circuit for an open, a short to ground or a short to battery voltage. See WIRING DIAGRAMS . Repair or replace as necessary.

Check sensor signal ground circuit for an open. See WIRING DIAGRAMS . Repair or replace as necessary.

Check evaporator temperature sensor circuit for an open, high resistance or a short to battery voltage. See WIRING DIAGRAMS . Repair or replace as necessary.

Check evaporator temperature sensor circuit for a short to ground. See WIRING DIAGRAMS . Repair or replace as necessary.

Check coolant temperature sensor signal circuit between instrument cluster and A/CCM for an open, high resistance or a short to battery voltage. See WIRING DIAGRAMS . See PIN VOLTAGE TESTS under SYSTEM TESTS. Repair or replace as necessary.

Check coolant temperature sensor signal circuit between instrument cluster and A/CCM for a short to ground. See WIRING DIAGRAMS . Repair or replace as necessary.

Check heater matrix temperature sensor circuit for an open, high resistance or a short to battery voltage. See WIRING DIAGRAMS . Repair or replace as necessary.

Check heater matrix temperature sensor circuit for a short to ground. See WIRING DIAGRAMS . Repair or replace as necessary.

Check heater pump motor ground circuit for an open. See WIRING DIAGRAMS . Check for a locked heater pump motor. Repair or replace as necessary.

Check compressor clutch feedback circuit for an open or a short to ground. Check compressor clutch request circuit between A/CCM and ECM for an open or short to ground. Check compressor clutch relay drive circuit between ECM and relay for an open or a short to ground. Check compressor clutch activation circuit between clutch relay and clutch for an open or short to ground. See WIRING DIAGRAMS . Check compressor clutch relay and compressor clutch for proper operation. Repair or replace as necessary.

Check clock, data in and start circuits between control panel and A/CCM for an open or short. See A/C-HEATER CONTROL MODULE (A/CCM) TERMINAL ASSIGNMENTS (12-PIN CONNECTOR AC3) table under SYSTEM TESTS. See WIRING DIAGRAMS . Check for a control panel and/or A/CCM failure. Repair or replace as necessary.

Check data out circuit between control panel and A/CCM for an open or short. See A/C-HEATER CONTROL MODULE (A/CCM) TERMINAL ASSIGNMENTS (12-PIN CONNECTOR AC3) table under SYSTEM TESTS. See WIRING DIAGRAMS . Check for a control panel and/or A/CCM failure. Repair or replace as necessary.

SYSTEM TESTS

Note. Circuit and component testing information is not available from manufacturer. See PIN VOLTAGE TESTS . See WIRING DIAGRAMS .

A/C SYSTEM PERFORMANCE

Information is not available from manufacturer.

PIN VOLTAGE TESTS

Pin voltage charts are supplied to reduce diagnostic time. Checking pin voltages at Air Conditioning Control Module (A/CCM) determines whether it is receiving and transmitting proper voltage signals. (Scheme 9) Tests may also help determine if control unit wiring harness has a short or open circuit.

Scheme 9

A/C-HEATER CONTROL MODULE (A/CCM) TERMINAL ASSIGNMENTS (26-PIN CONNECTOR AC1)

A/C-HEATER CONTROL MODULE (A/CCM) TERMINAL ASSIGNMENTS (16-PIN CONNECTOR AC2)

A/C-HEATER CONTROL MODULE (A/CCM) TERMINAL ASSIGNMENTS (12-PIN CONNECTOR AC3)

A/C-HEATER CONTROL MODULE (A/CCM) TERMINAL ASSIGNMENTS (22-PIN CONNECTOR AC4)