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Actuator Calibration/Diagnostics and Cooldown Test

GENERAL INFORMATION
If the Heating Ventilation and Air Conditioning (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 wiring 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.

Radio Bezel and HVAC Control:




Radio Bezel and HVAC Control w/Rear Blower and Zone Control:




ACTUATOR CALIBRATION
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. 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.

NOTE: Cool-down will not occur on Heater Only units.

CALIBRATION/COOL-DOWN LED DISPLAY CODES

Calibration/Cooldown Test LED's:





NOTE: See chart 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 result 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

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.

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

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.

Blend/Passenger Actuator Background
The Blend/Passenger Actuator can move the temperature door in two directions. When the voltage at Pin 12 of the control module is high, about 11.5 volts, and the voltage at Pin 17 is low, about 1.5 volts, the door will move towards the Heat position. When Pin 17 is High and Pin 12 is Low the door will move towards the Cold position. When both Pins are high or both Pins are low, the actuator will not move. The Blend/Passenger feedback signal is a voltage signal that is supplied by the actuator to the control. The signal will be about 4.0 volts in the Heat position and 1.0 volt in the Cold position. As the position of the Blend/Passenger actuator changes, so will the feedback signal. The feedback signal is necessary for the correct positioning of the temperature door.

Driver Actuator Background
The Driver Actuator can move the temperature door in two directions. When the voltage at Pin 15 of the control module is high, about 11.5 volts, and the voltage at Pin 13 is low, about 1.5 volts the door will move towards the Cold position. When Pin 13 is High and Pin 15 is Low the door will move towards the Heat position. When both Pins are high or when both Pins are low, the actuator will not move. The Driver feedback signal is a voltage signal that is supplied by the actuator to the control. The signal will be about 4.0 volts in the Heat position and 1.0 volt in the Cold position. As the position of the Driver Actuator changes, so will the feedback signal. The feedback signal is necessary for the correct positioning of the temperature door.

Mode Actuator Background
The Mode actuator can move the mode door in two directions. When the voltage at Pin 18 of the control module is high, about 11.5 volts, and the voltage at Pin 12 is low, about 1.5 volts the door will move towards the Panel position. When Pin 12 is High and Pin 18 is Low the door will move towards the Defrost position. When both Pin are high or when both Pins are low, the actuator will not move. The Mode door feedback signal is a voltage signal that is supplied by the actuator to the control. The signal will be about 4.5 volts in the Panel position and 0.5 volts in the Defrost position. As the position of the Mode actuator changes, so will the feedback signal. The feedback signal is necessary for the correct positioning of the mode door.

FAIL CODES/LEVEL DISPLAY
Fail Codes/Level are displayed using the REAR WIPER and INTERMITTENT LED's flashing in sequence. The REAR WIPER LED represents the Level and the INTERMITTENT LED represents the Value. After Calibration/Diagnostics is completed, the control will begin flashing Level 1 codes. Depressing the WASH button will cycle to Level 2, depressing WASH again will cycle to Level 3. Each time the WASH button is depressed will cycle to the next level. After Level 5 is reached, you will cycle back to Level 1.

Failure Code Levels -- Wipe Button LED
Level Display
1 Fail Codes
2 Mode Potentiometer Test
3 Blend/Pass. Potentiometer Test
4 Evaporator Probe (A/C and Zone Units Only)
5 Driver Potentiometer (Zone Units Only)

Level 1 Failure Codes -- Intermittent Wipe Button LED
Code Definition
0 Passed ALL Tests
1 Mode Actuator Did Not Reach Defrost Position
2 Mode Actuator Did Not Reach Panel Position
3 Blend/Pass Actuator Did Not Reach Cold Stop
4 Blend/Pass Actuator Did Not Reach Heat Stop
5 Evaporator Probe Open
6 Evaporator Probe Shorted
7 Driver Actuator Did Not Reach Cold Stop
8 Zone/Driver Actuator Did Not Reach Heat Stop
9 Control Head Internal Failure

NOTE: If the Control is a Heater Only you will only cycle from Levels 1 to 3.

TEMPERATURE AND MODE POTENTIOMETER DIAGNOSTICS
A/C Units
The Temperature and Mode Potentiometer can be tested after calibration is complete by pressing the WASH button and cycling to Levels 2, 3 or 5 as displayed by the REAR WIPER LED. INTERMITTENT LED flash rate will change as the Temperature or Mode potentiometer is moved from one end to the other.

Heater Only Units
On Heater Only units you can only cycle to Levels 2 and 3. In each individual test the INTERMITTENT LED flash rate will change as the Temperature or Mode potentiometer is moved from one end to the other.

EVAPORATOR PROBE TEMPERATURE DIAGNOSTICS
The evaporator probe can be tested by using the INTERMITTENT LED to display the actual temperature the sensor is reading. The HVAC control module can only display temperatures from 1 to 99 degrees. To read the temperature, perform the following:
- Set Blower motor to any speed other than OFF
- Set A/C to ON, if A/C Clutch does not engage make sure Fail Codes 5 and 6 are cleared.To clear the error code 5 and 6 the evaporator probe and/or the wiring repair needs to be completed. Then, press and hold the intermittent wipe button for 5 seconds.
- Run Diagnostics (Depress REAR WIPER and REAR WASH)
- When Diagnostics is complete, Cycle to Level 4.

Display Sequence is as follows:
- REAR WIPER LED will display the Level
- INTERMITTENT LED will display ten's digit
- Short Pause
- INTERMITTENT LED will display the one's digit.

The HVAC control module will continue to cycle the Level and then Temperature until the level is changed or Calibration Diagnostics and Cool-down test is exited.



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