Cutlass Supreme V6-3100 3.1L MFI VIN M (1994)
Vacuum Solenoid Valve HVAC: Testing and Inspection
Type C-67
1. Check for vacuum to the solenoid box.
2. Check HVAC fuse and CLSTR fuse.
3. Move the temperature lever to full "Cold" and then full "Hot." Listen for the sound of the servo motor moving the valve through its full range.
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Check for a broken or partially broken wire inside of the insulation which could cause system malfunction but prove good in a continuity or
voltage check with a system disconnected. These circuits may be intermittent or resistive when loaded, and if possible, should be checked by
monitoring for a voltage drop with the system operational (under load).
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Check for proper installtion of aftermarket electronic equipment which may affect the integrity of other systems.