Actuator Calibration/Diagnostics and Cool Down Test
GENERAL INFORMATIONIf the HVAC control module is replaced, the Calibration Diagnostic and Cool-down tests will need to be performed. Once this group of tests have successfully passed, they can be performed individually. The engine must be running during the test to provide hot coolant for the heater, A/C compressor operation and to assure that the actuators are calibrated correctly The HVAC control module is capable of troubleshooting the system in approximately 120 seconds. If a condition is detected, an error code is displayed. The error code cannot be erased until the condition is repaired and the diagnostic test is performed. Check wire before replacing components.
CAUTION: Do not remove the actuators from the Heater-A/C unit assembly with power applied. Removal should only be done with the Ignition OFF. The actuators have no mechanical stops to limit the travel. If the actuator rotates and is not connected to the unit assembly, it will become out of calibration.
ACTUATOR CALIBRATION
Radio Bezel And HVAC Control:

Radio Bezel And HVAC Control, Rear Blower Motor Switch And Zone Control:

Mode, Blend and Zone (if equipped) door calibration compensates for mechanical variations in the actuators, HVAC control module and its linkages. In vehicle calibration can be entered from the control's front panel. If the REAR WIPE and INTERMITTENT LED's flash simultaneously when Ignition is cycled ON, the actuators have not been calibrated or during the previous calibration a failure occurred. Diagnostics will always occur during Calibration Diagnostic and Cool-down test.
DIAGNOSTICS
During the Actuator calibration, diagnostics are performed on the actuators and evaporator temperature Fin Sensor. Once diagnostics are completed the REAR WIPER and INTERMITTENT LED's will flash to indicate either a successful calibration or the appropriate fail code(s). At this time manual testing of the Blend, Mode and Driver (if equipped) potentiometers can be performed. If a failure is detected during Diagnostics a fault will be set in the control. When Ignition is cycled OFF and then ON or Diagnostics is aborted, the REAR WIPER and INTERMITTENT LED's will flash simultaneously showing that a failure has occurred. The control will not indicate the fail code, but only that a failure had occurred during the last diagnostics test. The only way to clear the failure codes is repeat the Calibration Diagnostic and Cool-down test, after all repairs are completed.
COOL-DOWN TEST
This test has been designed for performance testing of the A/C system at the manufacturing facility. If the HVAC control module is replaced, the Cool-down test will occur during Calibration test. Cool-down will not occur on Heater Only units. During the Cool-down test the control will monitor the temperature of the Fin Sensor. The A/C system must be able to bring the evaporator temperature down a predetermined minimum amount in less than 2 minutes.
Calibration/Cooldown LED Display Codes:

CALIBRATION COOL-DOWN LED DISPLAY CODES
See table for definition of flashing LED's. If no problems are found, the control functions normally.
CALIBRATION/DIAGNOSTICS TEST ENTRY
To Initiate Tests:
- Set Blower motor ON HIGH
- Set Mode position to Panel
- Open all A/C outlets
- Set Temperature to Cold (Both slide pots if equipped)
- Depress WASH and REAR WIPER button simultaneously for 5 Seconds (Until all LED's light)
Results:
- All LED's will turn on for 5 Seconds
- Calibration Test is running when REAR WIPER and INTERMITTENT are alternately flashing. Cool-down test is running if A/C and RECIRC are alternately flashing.
- Acceptable results is REAR WIPER LED is the only LED flashing. Push Rear Wiper to exit.
- After all tests have passed, Calibration Diagnostics and Cool-down can be run separately
COOL-DOWN TEST ENTRY
To Initiate Tests:
- Set Blower motor ON HIGH
- Set Mode position to Panel
- Open all A/C outlets
- Set Temperature to Cold (Both slide pots if equipped)
- Depress WASH and A/C simultaneously for 5 Seconds
NOTE: Prior to start of test, If the evaporator is already cold, the system will fail test. To correct, operate system with A/C OFF and the blower motor ON high for three minutes prior to starting test.
Results:
- All LED's will turn on for 5 Seconds
- Cool-down Test is running when A/C and RECIRC. are alternately flashing. If A/C and RECIRC. are flashing simultaneously, Cool-down has failed.
CALIBRATION DIAGNOSTICS AND COOL-DOWN ABORT
Test can be aborted by doing one of the following:
- Depressing Rear Window Defogger, RECIRC and Rear Wiper buttons.
- Cycling Ignition OFF and then ON.
- Control will automatically abort after 15 minutes from the time Calibration Diagnostics and Cool-down was entered.
The HVAC control module will return to normal operation or may indicate unsuccessful Calibration Diagnostics or Cool-down test by LED's flashing simultaneously.
EEPROM DATA
Calibration Diagnostics, Cool-down Status and evaporator temperature Fin Sensor values are stored in an EEPROM memory internal to the control. The microcomputer within the HVAC control module uses this information:
- To determine if Cool-down needs to run
- For proper position of the Heater-A/C unit assembly doors
ACTUATOR CALIBRATION AND DIAGNOSTICS
NOTE: Do not run actuators unless they are properly mounted on the HVAC control module.
Actuator end point calibration takes approximately 60 seconds. The REAR WIPER and INTERMITTENT LED's will flash alternately during the test. The control will cycle the Blend actuator(s) to the Heat stop first then back to Cold. After the Blend actuator(s) have been calibrated the Mode actuator will be cycled to Defrost and then to Panel. Successful calibration is defined as actuator travel falling within their minimum and maximum limits.