1999 GMC Jimmy Repair Question
GMC Jimmy Heater Problem
Do you live in an extremely cold region? Does the engine reach normal operating temp? What is your normal operating temp in degrees F? Do the heater hoses get hot? You might check for applicable hvac trouble codes. Some of the national brand autostores check codes for free.
If a temp door under the dash is having a problem, I'd have to get under the dash and check it out.
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