Manual A/C Control Head Illumination
NOTE:
After making any repairs, perform BODY VERIFICATION TEST
under VERIFICATION TESTS.
Possible Causes:
- Ground Circuit Open
- Panel Lamps Driver Circuit Open
- Control Head - Lamps Inoperative
Testing
- Turn ignition off. Disconnect the manual temperature control head C1 harness connector. See Figure . Ensure all lights are off. Measure the resistance between ground and the ground circuit. If the resistance is 5 ohms or less, go to next step. If the resistance is 5 ohms or more, repair the ground circuit for an open.
- Turn the park lights on. Measure the voltage of the panel lights driver circuit. Rotate the dimmer switch thumb wheel and observe the voltage change. If the voltage ranges from 3.5 volts or less, to 9 volts or more when the switch is rotated, check the bulbs. If OK, replace the control head. See MANUAL A/C-HEATER SYSTEMS - CONCORDE & INTREPID article in HVAC. If voltage is not as specified, repair the panel lights driver circuit for an open.
NOTE:
Ensure the panel lights operate properly on the instrument cluster before proceeding. If not, see DIAGNOSTIC TROUBLE CODE IDENTIFICATION
or SYMPTOM IDENTIFICATION
tables for related problems.