The heater on my 2009 works fine when it is first started, but as it gets the truck interior gets warm, cool air begins to flow out of the ductwork. I can increase the temperature and warmer air will come out for a while, but then cold air comes out again. Eventually I can't raise the temperature up anymore and cold air comes out again. Maybe there is a defective sensor somewhere, but where? Does anyone have any ideas on what could be causing this problem and what to do other than taking it to the dealer for an expensive repair?

Harv

 

next time it occurs, rev the engine up and see if you get heat at the higher rpm. if you do, the coolant level is low and air is in the system.

 

I will check the coolant level right away, but if it is low, why would it work fine at first after the engine is warm and then start blowing cool air after about a half an hour of driving? Thank you for the suggestion.

Harv

 

One possibility is:


If you have low coolant volume there will be air pockets in the cooling system. whenever air, instead of coolant fills the heater core; there will be no transfer of heat.

 

do u have dual climate, does it do the same on both sides. I had a issue similar to this in a 2004 but it got hot instead of cold, and it was the temp actuator that is mounted right above the hump in the center of the floor under the dash had two screws and a plug that when to it, it defaults to hot if something went wrong in the circuit. just unplugged it to start and see and it wouldn't change, but neither did the air temp, got a new switch at napa, took 5 minutes to change and have had no more issues. hope this helps you

 

My truck is in storage right now, but I will be able to check it Saturday. It does have dual temperature controls and the problem is on both sides. If it isn't low on coolant and the switch you mentioned is good, then there must be a defective sensor somewhere. I sure wish I had a service manual for this truck! Thanks for the switch suggestion.

Harv

 

well if it is on both sides at the same time and you have the dual temp controls i dont belive it would be in the switch i mentioned cause your truck should have two of these, the one i mentioned and another deep into the dash for the passenger side and its a mother to change. i would check the coolant level. other then that, im back to punting know.

 

Hey Harv,

I apologize for these concerns. If you would like to private message me with your VIN, current mileage, contact info and preferred dealership I will be happy to assist. Also, you can look into http://www.helminc.com/helm/homepage for a copy of your service manual. If there is anything else we can help you with, please don't hesitate to ask.

Anisha T (assisting Patsy)
Chevrolet Customer Care

 

My truck has 33,000 + miles on it. I will get the information you requested after Saturday and send it to you. Possibly it may be a stuck damper somewhere in the ductwork that doesn't move after the truck is fully warmed. Thanks for your offer to help and I will look at the Helms site.

Harv

 

Hi Anisha: I got the information you requested: The truck has 36,572 miles on it and the vin# is IGCEK29J19Z148240. The coolant is only about 1/2" below the cold full level when it is cold. I don't believe that small amount would be enough to make the heater malfunction. My local dealer is Preferred Chevrolet in Grand Haven, MI.