1991 GMC 3500 Pickup Repair and Maintenance
A guide to problems, costs, maintenance and repair for your 1991 GMC 3500 Pickup
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1991 GMC 3500 Pickup ProblemsHeating and AC Temperature and Air Delivery Mode Door Actuators May Fail
One or more heater & AC (HVAC) temperature and/or air delivery mode door actuator may fail, resulting in improper temperature or air delivery. If this occurs, fault code(s) should be stored in the HVAC control module which should assist in diagnoses.
The quick-connect fittings for the heater hoses tend to leak engine coolant. This problem commonly occurs because the metal housing has become brittle, which can break and cause leaks.
The air conditioning compressor may develop an abnormal noise and require replacement. We recommend that whenever an AC compressor is being replaced for a noise condition, a filter kit should be installed to prevent any metal particles in the system from damaging the new compressor.