Recently I have been having problems with my heater blowing cold air. Once the truck is up to temp, I turn on the heater - cold air, turn heater off then back on - warm air for a couple seconds then slowly goes cold again. After about 15 mins. or so of this it will start working fine. Does this sound like the control is going bad. Thanks

 

You may have a broken recert door or problems with the blend doors. But ck the coolant level 1st.

 

I assume your engine coolant is up to the proper level. Have you had the coolant drained at all? I've heard of people having air in the heater core which would cause cool air to come through the vents.

I've also heard a few people with broken HVAC housing components, like the blend door and such.

 

Yep you got it, talked to a mechanic friend of mine and he told me to check for air in the system. So I ran it awhile last night with the cap off and it was doing quite a bit of burping and was a little low on coolant as well. Working like a charm now. Thanks