I have a 2004 Sierra and I'm having intermittent heat problems took it to the dealership they told Me it was the hvac controll head, so I replaced the hvac controll head relearned the system and still have the same problem.
Intermittent heat problem needs to be checked step by step.
Could be a bad thermostat, low coolant level or leak, electrical problem-such as a loose wire.
For each of these possibilities do a step by step inspection. Pressure test for a coolant leak, do a wire by wire continuity test, look over the coolant level. Remove and replace the thermostat.
The wiring on these trucks is much smaller in size compared to the older trucks, therefore it is important to get a close up look at it to check for partial breaks in the wiring, the most common cause of intermittent wiring problems next to corrosion.
What led the Dealer to believe the hvac control head needed to be replaced. Just asking? Check first, replace parts only when you need to. Hope that dealer is giving you a full refund since the problem has not been fixed.
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