I have A 08 GMC Sierra 6.0 1500. My heat only works when I am driving the truck. It blows cold air when the truck is in park no matter how long it idles. Any ideas on what could be the issue?

Asked by Nov 24, 2015 at 06:36 AM about the 2008 GMC Sierra 1500 SLE1 Crew Cab 4WD

Question type: Maintenance & Repair

I have even driven the truck to get the heat
warm and then put it back in Park in let it
idle and it cools back off

1 Answer

1,355

i think it is your thermostat

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