DESCRIPTION
Electronic Automatic Temperature Control (EATC) system maintains selected in-car temperature. EATC A/C-heater operational controls are included in the Integrated Control Panel (ICP), located near center of instrument panel. (Scheme 3) Included in the ICP are the following
- AUTO and OFF buttons
- FAN (blower speed) rocker switch
- Function and override buttons
- TEMP (temperature) rocker switch
- Vacuum Fluorescent Display (VFD)
The VFD shows the set temperature, ambient temperature, blower speed and the Diagnostic Trouble Codes (DTCs). The ICP is connected to the Remote Climate Control (RCC) module with a dedicated 2-wire communications link.
The RCC module uses a microcomputer to analyze inputs from the in-car temperature sensor, ambient air temperature sensor, sunload sensor and function inputs made at the ICP by vehicle occupants.
Using these inputs, the RCC module determines the correct outputs for A/C compressor clutch engagement and blower speed. The RCC module also determines outputs controlling the A/C air temperature control door, heater air damper door, windshield defroster door, and the A/C air inlet door positions. System has a self-diagnostic feature in which Diagnostic Trouble Codes (DTCs) are stored in the microprocessor memory and displayed on the VFD.
The A/C air temperature control door is operated by an electric door actuator motor. The remaining distribution doors are controlled by vacuum actuated motors.
Scheme 3
TEST F - EATC SYSTEM INOPERATIVE, INTERMITTENT OR IMPROPER OPERATION
- Perform Self-Diagnostic Test Simultaneously depress OFF and FLOOR buttons, then press AUTO button within 2 seconds. Display will show a pulse tracer going around the center of the display window for up to 30 seconds while test is running. If no Diagnostic Trouble Codes (DTCs) are displayed, go to next step. If DTCs are displayed, perform indicated test. See «SELF-DIAGNOSTIC TEST CODE DIRECTORY»(ref-39943-S01716573502001011200000) table.
- Check Blower Manual Override Low Speed Operation Turn ignition on. Turn A/C system on. Press and hold FAN (-) button. If blower slows to low speed, go to next step. If blower does not slow to low speed, go to «TEST K»(ref-39943-S13730443462001011200000) .
- Check Blower Manual Override High Speed Operation Turn ignition on. Turn A/C system on. Press and hold FAN (+) button. If blower goes to high speed, go to next step. If blower does not go to high speed, go to «TEST J»(ref-39943-S40685058112001011200000) .
- Verify Defrost Override Operation Press the F-DEF button and check airflow discharge. Airflow should be from windshield defrost nozzle and side window demister nozzle. Air inlet duct door should be in the outside air position. If airflow is as specified, go to next step. If airflow is not as specified, see «VACUUM SYSTEM TEST»(ref-39943-S10026305352001011200000) under TESTING. Repair system as necessary.
- Verify Floor Override Operation Press floor icon button and check airflow discharge. Airflow should be from heater outlet floor duct. If airflow is as specified, go to next step. If airflow is not as specified, see «VACUUM SYSTEM TEST»(ref-39943-S10026305352001011200000) under TESTING. Repair system as necessary.
- Verify VENT Override Operation Press VENT button and check airflow discharge. Airflow should be from the A/C registers. If airflow is as specified, go to next step. If airflow is not as specified, see «VACUUM SYSTEM TEST»(ref-39943-S10026305352001011200000) under TESTING. Repair system as necessary.
- Verify That A/C Clutch Does Not Engage In VENT Mode Press VENT button. Check that VENT is in display window. Ensure that A/C clutch is not engaged. If both conditions are met, go to next step. If both conditions are not met, check constant control relay module or powertrain control module. See the TESTS W/CODES article in the ENGINE PERFORMANCE section.
- Verify MAX A/C Override Operation Ensure ambient air temperature is greater than 41°F (5°C). Press MAX A/C button. If air inlet duct door is closed to outside air, go to next step. If air inlet duct door is not closed to outside air, see «VACUUM SYSTEM TEST»(ref-39943-S10026305352001011200000) under TESTING. Repair system as necessary.
- Verify MAX A/C Operation Press MAX A/C button. Check that MAX A/C is in display window. Ensure that A/C clutch is engaged. If both conditions are met, go to next step. If both conditions are not met, check constant control relay module or powertrain control module. See the TESTS W/CODES article in the ENGINE PERFORMANCE section.
- Verify AUTO Operation Press AUTO button. Preset temperature and AUTO should appear in display window. If display is correct, system is operating properly. Test is complete. If display is not correct, perform «PRELIMINARY INSPECTION»(ref-39943-S36964688752001011200000) and repeat step 1).