Automatic A/c-Heater Systems: Other Saab 9-3 I

AUTOMATIC CLIMATE CONTROL (ACC) CONTROL MODULE

Automatic Climate Control (ACC) control unit consists of a control panel with an active function display and control buttons, and an integrated control module. (Scheme 7) Under normal conditions the ACC control module maintains selected temperature for driver and passengers.

AUTO Mode

When AUTO mode button is pressed, cabin temperature is automatically maintained by controlling fan blower motor speed, recirculated air, and air distribution. ACC display panel can be toggled between basic and full display by pressing AUTO button. Basic display shows current settings for AUTO, temperature, heated rear window and mirrors, ECON, and air recirculation. Full display shows all settings including AUTO, temperature, fan blower motor speed, air distribution, heated rear window and mirrors, OFF, ECON, and air recirculation. (Scheme 7) In AUTO mode, when outside ambient air temperature is more than 32°F (0°C), A/C compressor is activated automatically. ECON, heated rear window and mirrors, recirculation and temperature increase or decrease can be selected without leaving AUTO mode.

Temperature Selection

Selection of in-vehicle temperature occurs in 2°F (1°C) increments, between 58-81°F (15-27°C). If selected temperature is more than 81°F (27°C), HI will be displayed as selected temperature. ACC system will set fan blower motor speed to 18-amps, air distribution to defrost/floor position, mixed-air position to maximum heat position, recirculated air to OFF position, and full display.

If selected temperature is less than 58°F (15°C), LO will be displayed as selected temperature. ACC system will set fan blower motor speed to 25.5-amps, A/C ON (ECON OFF), air distribution to panel position, mixed-air position to maximum cold position, recirculated air to ON position, and full display.

Defrost Mode

When front defrost button is pressed one time, ACC system will set fan blower motor speed to 18-amps, A/C ON (ECON OFF), air distribution to defrost position, normal temperature control, recirculated air to OFF position, heated rear window is turned ON, and AUTO goes off. If front defrost button is pressed a second time, air distribution remains in defrost position and all other functions are restored if they have not been manually changed since front defrost was initially selected.

Defrost/Floor Mode

When front defrost and floor mode buttons are pressed simultaneously, air distribution is set to front defrost and floor outlets, AUTO goes off, and button symbols are displayed on ACC panel display.

Floor Mode

When floor mode button is pressed, air distribution is set to floor outlets, AUTO goes off, and button symbol is displayed on ACC panel display.

Floor/Panel Mode

When floor and panel mode buttons are pressed simultaneously, air distribution is set to floor and panel outlets, AUTO goes off, and button symbols are displayed on ACC panel display.

Panel (Vent) Mode

When panel mode button is pressed, air distribution is set to panel outlets, AUTO goes off, and button symbol is displayed on ACC panel display.

Recirculated Air Mode

When recirculated air button is pressed it manually shifts air recirculation ON or OFF. AUTO will be displayed during manual air recirculation operation. AUTO mode button must be pressed to resume automatic control of air recirculation. When air recirculation is ON, recirculation symbol will be displayed on ACC panel display.

Heated Rear Window & Door Mirrors

Heated rear window and door mirrors button turns heating elements on and off. Manual activation cannot occur until engine has been started. Heated rear window and door mirrors function operation time depends on ambient air temperature. When temperature is approximately 41°F (5°C) operation time is about 4 minutes. When temperature is less than approximately 14°F (-10°C) maximum operation time is about 10 minutes. It can, however, be manually turned off sooner if desired. When activated, heated rear window symbol will be displayed on ACC panel display.

Fan Blower Motor Speed Control Buttons

Buttons may be used to increase or decrease fan blower motor speed. (Scheme 7) Fan symbol and fan speed (horizontal bars) will be shown on display panel and AUTO will not be displayed. If a button is depressed and held down, fan speed will increase or decrease continually. Pressing AUTO button will return to automatic fan speed control. If a fan speed of zero is selected, A/C function will be disengaged and ECON will be displayed.

ECON (Economy) Mode

Pressing ECON (economy) mode button turns ECON on and off. When ECON is on, AUTO will still be displayed, A/C compressor is shut off, recirculation is moved to off position, and ECON will be displayed.

OFF Button

When OFF button is pressed, ACC system is shut off. ACC system can be turned on again by pressing AUTO or by pressing OFF button a second time. When ACC system is turned off, fan blower motor current is zero, compressor is turned off, air distribution damper stays in current position, air-mixing damper moves to maximum cold position, recirculation is turn off, and rear window defogger is turned off. Only recirculation, OFF and AUTO buttons operate. OFF will be shown on display panel.

Scheme 7

A/C COMPRESSOR CIRCUIT

A/C request is automatic for ACC system as long as ECON or OFF buttons have not been selected and ambient air temperature is more than 32°F (0°C). A/C request is sent to Dashboard Integrated Central Electronics (DICE) control module. DICE control module will evaluate sensor inputs and when predetermined conditions are satisfied, A/C compressor relay will be energized. A/C compressor runs, even when cooling is not required, to prevent the misting of windshield in damp weather.

Before A/C relay is energized, A/C system pressure in condenser must be 29-392 psi (2.0-27.6 kg/cm 2 ), evaporator temperature must be more than 39°F (4°C), and engine coolant temperature must be less than 259°F (126°C). When A/C relay is energized, ECM adjusts idle speed based on engine load and speed. When A/C relay is energized, power to A/C compressor clutch is supplied through compressor temperature sensor. During heavy engine loads or high compressor temperatures A/C relay will be de-energized.

Engine Coolant Temperature Sensor

The engine coolant temperature is used by Dashboard Integrated Central Electronics (DICE) control module to control the radiator fan and to switch off A/C compressor at high coolant temperatures. ACC control module uses engine coolant temperature as an input value to determine air distribution position and fan blower motor speed during cold starts.

Cabin (In-Vehicle) Temperature Sensor

Note. Ensure cigarette lighter or lighter socket cover is in place. Warm air will be drawn from rear of instrument panel through lighter socket and into cabin temperature sensor causing an incorrect value reading if cigarette lighter or lighter cover is not in place, as the in-vehicle temperature sensor fan will draw air through the hole for the cigarette lighter.

Cabin (in-vehicle) temperature sensor is located in center of instrument panel, below ACC control module. (Scheme 8) ACC control module compares in-vehicle temperature sensor value with selected temperature and ambient air temperature to determine if mixed-air temperature should be increased or decreased.

As difference between selected temperature and in-vehicle temperature increases, fan blower motor speed is increased. Ambient air temperature is used as a replacement value for in-vehicle temperature when ignition is turned on. When system stabilizes, the calculated head level temperature for driver and front seat passenger is used.

When ignition is turned off, the in-vehicle temperature sensor intake fan will continue to run for about 10 minutes. This decreases the possibility of an incorrect temperature value if the vehicle is restarted within a short time.

Mixed-Air Temperature Sensor

The mixed-air temperature sensor is of the Negative Temperature Coefficient (NTC) type, with a pointed tip which is inserted into one of the climate control unit floor vents. (Scheme 8) Airflow at this location is completely blended and constant, regardless of air distribution damper position.

When ACC control module has decided what temperature the mixed air should have, the mixed-air temperature sensor value is used to adjust position of air-mixing damper. If selected temperature is HI or LO, the mixed-air sensor value is not used. If mixed-air temperature value cannot be obtained, coolant temperature and air-mixing damper position are used to calculate a default value.

Ambient Air (Outside) Temperature Sensor

Ambient air temperature sensor is located under front bumper. (Scheme 8) Ambient air temperature is sent to Saab Information Display (SID) on instrument panel and passed on to ACC control module.

Ambient air temperature is used by ACC control module to correct in-vehicle temperature and also to control fan blower motor speed. In-vehicle temperature is corrected so that it corresponds to the physical perception of the selected temperature. This means that the actual in-vehicle temperature is higher than the selected temperature at low ambient temperatures.

Even at high ambient temperatures, the actual in-vehicle temperature is higher than the selected temperature, but the difference is less. At ambient temperatures below 41°F (5°C) and above 68°F (20°C), blower fan speed increases to achieve a more uniform in-vehicle temperature.

Solar Sensor

Solar sensor is located on top of dashboard, and is used to measure infrared radiation (radiated heat). (Scheme 8) When solar radiation has increased and ambient air temperature is more than 59°F (15°C), ACC control module increases fan blower motor speed in an attempt to lower temperature.

Fan blower motor speed is changed immediately when solar sensor radiation changes. Because solar sensor measures infrared radiation, it cannot be tested using a fluorescent light. An incandescent light (at least 60 watts) or sun light must be used for testing.

AIR-MIXING DAMPER STEPPING MOTOR

Air-mixing damper stepping motor is located on evaporator case, behind glove box. (Scheme 8) There are 2 windings in stepping motor. A voltage is applied to the windings in a special order with short pulses, causing the motor to move in short steps. The direction of motor rotation can be changed. When motor is stationary, current is applied continuously to both windings to lock motor.

By sending a definite number of pulses, ACC control module knows how much the damper moves. A feedback signal to the ACC control module is not required. ACC control module calibrates position of damper by rotating it to an end position so that exact position of the damper is known.

Calibration of damper stepping motor must be carried out if the battery has been disconnected or discharged, if the ACC control module or stepping motor has been replaced, or if stepping motor damper position has been changed. See ACC CONTROL MODULE CALIBRATION under PROGRAMMING.

The air-mixing damper position is controlled by ACC control module based on mixed-air temperature sensor. In-vehicle, selected, and ambient (outside) temperatures are used to determine mixed air temperature. If air-mixing damper is at maximum cool position, and this position is insufficient to maintain selected temperature, recirculated air mode will be selected. If the selected temperature is at its highest (HI) or lowest (LO) setting, the air-mixing damper will be set to the maximum heat or maximum cool position.

Scheme 8

AIR DISTRIBUTION DAMPER STEPPING MOTOR

Air distribution damper stepping motor is located on evaporator case, behind ACC control module. (Scheme 8) There are 2 windings in stepping motor. A voltage is applied to the windings in a special order with short pulses, causing the motor to move in short steps. The direction of motor rotation can be changed. When motor is stationary, current is applied continuously to both windings to lock motor. Air distribution damper directs airflow to various air ducts.

Calibration of damper stepping motor must be carried out if the battery has been disconnected or discharged, if the ACC control module or stepping motor has been replaced, or if stepping motor damper position has been changed. See ACC CONTROL MODULE CALIBRATION under PROGRAMMING.

Floor and panel/floor mode settings are not used in AUTO mode. If required mixed-air temperature is high, air distribution will be set to the defrost/floor position. If required mixed-air temperature is low, air distribution will be set closer to the defrost position. If required mixed-air temperatures are extremely low, air distribution will be set to the panel position.

The desired air distribution can also be selected manually on the ACC control module. Air distribution is shown by means of symbols on ACC control module display.

AIR RECIRCULATION DAMPER DC MOTOR

Air recirculation damper DC motor is located on right side of climate control unit. (Scheme 8) Air recirculation damper is operated by a DC motor. There are damper 2 positions. When motor has rotated damper to either end position, current passing through the motor's windings is limited by two Positive Thermal Coefficient (PTC) resistors built into the motor. PTC resistor resistance increases as heat increases. ACC control module will shut off output after 10 seconds.

When ignition has been turned off for more than 10 minutes, recirculated air will be selected within 30 seconds after engine start. Recirculated air will only be selected if ambient air temperature is more than 77°F (25°C) and selected in vehicle temperature is the lowest possible.

Recirculated air will be selected when

1. Cooling effect in fresh air position is insufficient based on an ambient air temperature of more than 99°F (37°C) and high solar sensor signal voltage.
2. Vehicle speed is 5 MPH or less for an extended period, requested mixed air temperature is less than 45°F (7°C) and ambient air temperature is more than 86°F (30°C).
3. Ambient air temperature is more than 68°F (20°C) and engine coolant temperature exceeds 244°F (118°C), indicating the possibility of engine overheating.

Recirculated air mode can also be selected manually. Recirculated air position is indicated by a symbol in the ACC control module display. When ignition is turned off air recirculation damper will switch to fresh air position within 10 seconds.

Cold Start Mode

During a cold start, the windshield must first be defrosted, then the cabin must be warmed up as soon as possible. When ambient air and engine coolant temperatures are low, fan blower motor speed is adjusted so that air temperature at the heater core is as warm as possible.

If calculated cabin temperature at head level of driver is lower than selected temperature and ambient temperature is less than 43°F (6°C), air distribution will be dependent on engine coolant temperature until ACC control module selects defrost/floor mode position.

In cold start mode, fan blower motor current is dependent on engine coolant and ambient air temperatures. When coolant temperature is less than 68°F (20°C), fan blower motor current is approximately 5.0 amps. Fan blower motor current will gradually increase as coolant temperature increases. Fan blower motor current will increase to approximately 22.5 amps when coolant temperature is approximately 190°F (88°C). ACC control module will return to its normal operating mode when cabin temperature in the same as selected temperature.

Hot Start Mode

During a warm start, cabin temperature must be reduced as soon as possible after engine start. If calculated cabin temperature is more than selected temperature, cold air will be blown out vents until cabin temperature stabilizes.

If calculated cabin temperature at head level of driver is more than 41°F (5°C) from selected temperature, warm start function will be activated. Air distribution damper will be in panel position and fan blower motor current will be 20.0 amps at start-up. If necessary, fan blower motor current will be slowly increased to 25.5 amps. When cabin temperature is less than 41°F (5°C) from selected temperature, ACC control module will return to normal operating mode.

CONVERTIBLE TOP OPEN OPERATING MODE

When convertible top is lowered ACC control system will operate as follows

1. AUTO operation mode is cancelled.
2. Displayed temperature is replaced by current step position of air-mixing damper in steps from 1-10, where step 10 is maximum heating.
3. Air-mixing damper will automatically move to closest step position (0-10) last used when the top was closed.
4. Recirculated air damper moves to fresh air position.
5. A/C system is turned off.
6. Heated rear window/door mirrors function is turned off.

When convertible top is closed, ACC system will return to settings in effect when top was opened, provided ignition has not been turned off during that time. If ignition has been turned off, ACC system will activate AUTO mode. When convertible top is open, all manual functions can be selected, except heated rear window/door mirrors and recirculation.

FAN BLOWER MOTOR

Fan blower motor is powered directly from circuit +30 and fuse "C" (30-amp), located in main fuse/relay box at left end of dashboard. Fan blower motor ground is provided through fan control unit. (Scheme 8) Fan control unit is controlled by ACC control module. Fan control unit is controlled by an analog current of 0-5 volts from ACC control module 39-pin connector terminal No. 14 (Gray/Red wire on 2000 models; Red/Gray wire on 2001 models). Battery voltage is supplied to fan control unit from ACC control module 39-pin connector terminal No. 5 (Pink/White wire on 2000 models; White/Pink wire on 2001 models). Fan blower motor speed will increase as control current increases.

Fan blower motor speed is affected in AUTO mode as follows

1. An increased difference between selected temperature and in-vehicle temperature will increase fan blower motor speed.
2. Ambient temperatures less than 41°F (5°C) or more than 68°F (20°C) increase fan blower motor speed.
3. Increased solar intensity at ambient temperatures more than 59°F (15°C) increase fan blower motor speed. Desired fan blower motor speed can also be selected manually on ACC control module. Fan blower motor speed has 10 speed steps of about 2 amps each. If blower fan speed button is pressed for more than one second, fan speed will increase or decrease automatically. Fan blower motor speed bars are displayed on ACC control module display.

HEATED REAR WINDOW

If in-vehicle temperature is lower than 50°F (10°C) after starting engine, electric heating of the rear window and door mirrors is switched on automatically. This takes place after a delay of 10 seconds by a short pulse being sent to Dashboard Integrated Central Electronics (DICE) control module.

The DICE control module grounds a feedback lead to the ACC control module, causing the symbol for the heated rear window to light up in the ACC control module display.

On the basis of battery voltage, the DICE control module regulates the length of time heated rear window is on (12 minutes maximum). Regardless of whether the ACC control module has switched the heated rear window on or off, it can be controlled manually from the ACC control module.

ACC CONTROL MODULE PROGRAMMING

Note. Manufacturer has found that approximately half of all ACC control modules thought to be faulty were actually user programmed. Before replacing ACC control module ensure user programming has been cancelled and malfunction verified. Ensure vehicle owner is aware of how user programming functions.

User Programming

ACC control module can be user programmed. User programming saves manual settings that are used by ACC control module when vehicle is started. Functions not selected manually during user programming will be controlled automatically.

Programming is carried out by simultaneously pressing ECON and fan blower motor speed up buttons. (Scheme 7) Cancelling user programming is done by simultaneously pressing floor mode and heated rear window/door mirrors button. In both instances, selection is acknowledged by flashing background lighting.

ACC control module is active for 10 minutes after ignition has been turned off. If ignition is turned on during this 10 minute period any manual selections made during previous driving will be retained. If ignition is turned on after 10 minute period, user programmed settings will be used. ACC control module can be programmed using OBD-II scan tool to always start with any manual selections made.

Increased User Programming

Increased user programming allows user to change activation parameters of certain automatic functions. These selections are stored and used by ACC control module until programming is cancelled, activating default parameters. Programming and cancellation of selections is done by pressing ECON or heated rear window/door mirrors button for more than 1.2 seconds. Selection will be acknowledged by an audible signal sounding, selected function symbol flashing 4 times on display panel, and by corresponding text displays on Saab Information Display (SID) panel changing.

During ECON function programming, SID will display ACC: LO TEMP, A/C CTRL. During ECON function cancelling, SID will display ACC: NORMAL, A/C CTRL. When ECON function is programmed the A/C compressor will not operate until ambient air temperature is more than 55°F (13°C). During standard operation, the A/C compressor will not operate until ambient air temperature is more than 32°F (0°C).

During heated rear window function programming, SID will display ACC: MANUAL, RDEFR CTRL. During heated rear window function cancelling, SID will display ACC: AUTO, RDEFR CTRL. When heated rear window function is programmed, operation of heated rear window is switched to manual control only. During standard operation, the heated rear window will be activated within 5 seconds when ambient air temperature is less than 41°F (5°C).

ACC FAN BLOWER MOTOR NOT OPERATING

1. Turn ignition off. Check fuse "C" (30-amp), located in main fuse/relay box at left end of dashboard. Fan blower motor ground is provided through fan control unit. (Scheme 8) If fuse is okay, go to next step. If fuse is not okay, replace fuse and go to step 8.
2. Turn ignition off. Locate fan blower motor connector under intake air filter and disconnect connector. Connect a test light between ground and connector terminal No. 3 (Red wire). If test light illuminates, go to next step. If test light does not illuminate, repair Red wire as necessary. See «WIRING DIAGRAMS»(ref-97912-S27444300572001051400000). When repairs are completed, go to step 8.
3. Connect test light between fan blower motor connector terminals No. 3 (Red wire) and No. 5 (Brown wire). If test light illuminates, go to next step. If test light does not illuminate, repair Brown wire as necessary. See «WIRING DIAGRAMS»(ref-97912-S27444300572001051400000). When repairs are completed, go to step 8.
4. Using a heavy gauge jumper wire, ground fan blower motor terminal No. 5 (Brown wire). Using another heavy gauge, fused (30-amp) jumper wire, apply battery voltage to fan blower terminal No. 3 (Orange wire). If fan blower motor operates at full speed, go to next step. If fan blower motor does not operate at full speed, ensure circuits between fan blower motor terminals and motor are okay. Repair as necessary. If circuits are okay, replace fan blower motor. See «WIRING DIAGRAMS»(ref-97912-S27444300572001051400000). When repairs are completed, go to step 8.
5. Disconnect fan blower motor speed control unit 8-pin connector located on passenger-side of climate control unit. Connect a test light between ground and harness side of speed control unit 8-pin connector female terminal No. 5 (Pink/White wire on 2000 models; White/Pink wire on 2001 models). If test light illuminates, go to next step. If test light does not illuminate, repair wire (Pink/White wire on 2000 models; White/Pink wire on 2001 models) between speed control unit and ACC control module 39-pin connector terminal No. 5. When repairs are completed, go to step 8.
6. Connect test light between battery voltage and harness side of speed control unit 8-pin connector female terminal No. 3 (Black wire). If test light illuminates, go to next step. If test light does not illuminate, repair Black wire between speed control unit and ACC control module 39-pin connector terminal No. 3. When repairs are completed, go to step 8.
7. Check circuits between fan blower motor speed control unit and ACC control module. See «WIRING DIAGRAMS»(ref-97912-S27444300572001051400000). Repair circuits as necessary. When repairs are completed, go to next step. If circuits are okay, go to «DTC B2425: FAN BLOWER MOTOR CONTROL VOLTAGE»(ref-97912-S23622527722001051400000).
8. Using scan tool, clear all DTCs from all systems. Recheck A/C system operation for original complaint. If A/C system is operating properly and no DTC has been detected, repair is complete. If A/C system is not operating properly and/or a DTC has been detected, ACC control module may need to be replaced. See «CONTROL MODULES»(ref-97912-S29574280822001051400000).

Fault Conditions

The following conditions may cause DTC to set

1. An open circuit or short to battery voltage between solar sensor and ACC control module. See «WIRING DIAGRAMS»(ref-97912-S27444300572001051400000) .
2. When DTC is detected ACC control module uses a replacement value of zero volts which is interpreted as no light is being radiated.

The following conditions may cause DTC to set

1. Open circuit, short to ground or short to battery voltage.
2. If there are 5 consecutive periods without a mixed-air temperature sensor signal. Every 440 milliseconds ACC control module looks for a mixed-air temperature sensor signal.

The following conditions may cause DTC to set

1. Open circuit or a short to battery voltage. Voltage measured at ACC control module 39-pin connector terminal No. 20 (Blue/Yellow wire) will be more than 4.9 volts.
2. There is a short to ground. Voltage measured at 39-pin connector terminal No. 20 (Blue/Yellow wire) is less than 0.1 volt.
3. If there are 5 consecutive periods without a cabin temperature sensor signal. Every 440 milliseconds ACC control module looks for a cabin temperature sensor signal.

A DTC will set

1. When current on an ACC control module stepping motor output exceeds a certain value. DTC set will be for a short circuit.
2. When current on an ACC control module stepping motor output is less than 55 mA. DTC set will be for an open circuit.
3. During ACC control module monitoring and calibration, if a malfunction is detected.

A loose or jammed damper DTC will set

1. When ACC control module moves stepping motor toward an end position and stepping motor continues more than 20 percent past expected position. This would be consistent with a loose damper.
2. When stepping motor is operating within a 10-90 percent range and ACC control module detects excessive voltage usage consistent with a jammed damper. Air distribution damper stepping motor operating range is considered to be 0-100 percent. During stepping motor operation ACC control module monitors stepping motor voltage use.
3. If ACC control module has not been calibrated.
4. During monitoring and calibration if a malfunction is detected. Stepping motors are continuously monitored by ACC control module.

A DTC will set

1. When a short to battery voltage is indicated between air recirculation motor and ACC control module when air recirculation motor is not activated. Voltage measured at ACC control module 39-pin connector terminal No. 21 (Red wire) will be more than 9 volts.
2. When a short to ground and open is indicated between air recirculation motor and ACC control module when air recirculation motor is not activated. Voltage measured at ACC control module 39-pin connector terminal No. 21 (Red wire) will be less than 3 volts.
3. There are 5 consecutive voltage measurements (one every 440 milliseconds).

A DTC will set if a short to ground or battery voltage is detected.

A DTC will set

1. When voltage on an ACC control module stepping motor output exceeds a certain value. DTC set will be for a short circuit.
2. When control voltage on an ACC control module stepping motor output is less than 55 mA. DTC set will be for an open circuit.
3. During ACC control module monitoring and calibration if a malfunction is detected.

A DTC will set

1. When ACC control module moves stepping motor toward an end position and stepping motor continues more than 20 percent past expected position. A DTC for a loose damper will be set.
2. When stepping motor is operating within a 10-90 percent range and ACC control module detects excessive voltage usage. Mixed-air distribution damper stepping motor operating range is considered to be 0-100 percent. During stepping motor operation ACC control module monitors stepping motor voltage use. A DTC for a jammed damper will be set.
3. If ACC control module has not been calibrated.

A DTC will set

1. During monitoring if a malfunction is detected. ACC control module measures voltage every 40 milliseconds.
2. When voltage measured at ACC control module 39-pin connector terminals No. 36 (Yellow/Green wire), No. 38 (Blue/Red wire on 2000 models; Red/Blue wire on 2001 models) or No. 39 (Yellow/Brown wire on 2000 models; Brown/Yellow wire on 2001 models) is more than 0.4 volt.

SYSTEM TESTS

A/C SYSTEM PERFORMANCE

1. Park vehicle out of direct sunlight. Connect manifold gauge set. Start engine and allow it to idle at 1500-2000 RPM. Ensure all panel vents are open. Select lowest temperature setting (LO is shown on display panel). Set A/C controls to recirculated air and panel (vent) mode.
2. Insert thermometer in center vent. Operate system for 5 minutes to allow system to stabilize. Measure temperature. Temperature must be approximately 43-54°F (6-12°C) at center vent, with high-side and low-side pressures within specification. Difference between turn-on and turn-off should be 37-43°F (3-6°C). See «SPECIFICATIONS»(ref-97912-S36884146822001051400000) table at beginning of article.

ACC CONTROL MODULE PIN VOLTAGE CHECK

Checking pin voltage or resistance values at the ACC control module determines whether it is receiving and transmitting proper input/output signals. Measure values between pin numbers or battery terminals specified in ACC CONTROL MODULE PIN VOLTAGE SPECIFICATIONS table. Unless otherwise specified in table, ignition should be on. All values listed are approximate. see scheme 4

ACC CONTROL MODULE PIN VOLTAGE SPECIFICATIONS (1)

CONTROL MODULES

Manufacturer has found many control modules that have been replaced were not the cause of the problem and replacement of the control module did not correct the problem. Upon examination, these control modules were found to be free of defects. Before replacing a suspect control module, preform the following

1. Before replacing ACC control module, ensure that all user-programming has been cleared. See «ACC CONTROL MODULE PROGRAMMING»(ref-97912-S37833483382001051400000) under PROGRAMMING.
2. Ensure all control module power supply and ground circuits are okay and connections are clean and tight. See «WIRING DIAGRAMS»(ref-97912-S27444300572001051400000) .
3. Using a scan tool or DVOM ensure control module input and output signal values are reasonable. If replacing ACC control module, see «ACC CONTROL MODULE PIN VOLTAGE CHECK»(ref-97912-S06327104162001051400000) . Before replacing TRIONIC engine control module or DICE control module, see appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE for specific testing procedures.
4. Control modules are sensitive to static electricity. Before touching a control module touch a ground point. Never touch control module pins.
5. Connect test light, DVOM or scan tool and wiggle wiring harness at several points and in different directions to detect intermittent opens and/or shorts. See «WIRING DIAGRAMS»(ref-97912-S27444300572001051400000) . Preform repairs as necessary and recheck.
6. Using a scan tool, ensure that all functions are operating properly. A fault in one output signal may affect another output signal.
7. If problem continues, replace control module with a known-good control module and recheck. Replace control module if problem is corrected.

CABIN TEMPERATURE SENSOR

Cabin temperature sensor is supplied with 5.0 volts through a 10,000 ohm resistor in ACC control module from 39-pin connector terminal No. 20 (Blue/Yellow wire). Cabin temperature sensor ground is supplied through ACC control module connector terminal No. 39 (Yellow/Brown wire on 2000 models; Brown/Yellow wire on 2001 models). As temperature decreases sensor resistance increases. See CABIN TEMPERATURE SENSOR RESISTANCE table. Cabin temperature sensor suction motor is supplied with 12 volts from ACC control module connector terminal No. 15 (Yellow/Red wire on 2000 models; Red/White wire on 2001 models). Suction motor ground is supplied through fan blower motor switch connector terminal No. 1 (Black wire).

CABIN TEMPERATURE SENSOR RESISTANCE

Mixed-air temperature sensor is supplied with 5.0 volts through a 10,000 ohm resistor in ACC control module from 39-pin connector terminal No. 19 (Violet wire). Mixed-air temperature sensor ground is supplied from ACC control module 39-pin connector terminal No. 38 (Blue/Red wire on 2000 models; Red/Blue wire on 2001 models). As temperature decreases sensor resistance increases. See MIXED-AIR TEMPERATURE SENSOR RESISTANCE table.

MIXED-AIR TEMPERATURE SENSOR RESISTANCE

FAN BLOWER MOTOR SPEED CONTROL UNIT

Note. DO NOT use aluminum spacer supplied with fan blower motor speed control unit.