Improper HVAC Temperature and/or Air Delivery Due to Failed Mode Door Actuator on GMC 2500 Pickup

Problem Description and Possible Solution

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.

Problem Data
RepairPal Verified
Average mileage: 215,675 (180,000–251,350)
11 model years affected: 1990, 1991, 1992, 1993, more1994, 1995, 1996, 1997, 1998, 1999, 2000
13 people reported this problem
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Heater never does what i want it to.
left side of defrost vent is always in the open position