2002 chev truck heater issue

[hunterpete]

i have a question for all the pro's on here. i have a 02 chev pickup with a v6, ive been having problems with the heater, it will work fine, blowing hot air, then it will out of the blue just stop and blow cold air. some times it will come back to hot some times it wont till i start it again, i have a idea what it is. any body else have ideas?

[Jeremy airjer W]

Low on coolant?

[hunterpete]

no coolant is fine, the only time i've had to add what when i had a hose leak.

[BobT]

Is it possible for a water pump to go bad without leaking out the weephole? What about belt slipping? I would expect to hear it though.

[hunterpete]

its not overheating, its an issue with the heater, will blow hot air but some times it will quit and just blow cold air

[Jeremy airjer W]

Temperature blend door actuator or the HVAC control head are the only two things left?

[hunterpete]

ty airjer, i hope those things are it. iam thinkin a head gasket maybe?

I have no clue how to look at the things you suggested. how would i go about that?

[hanson]

Check this post out...

http://www.hotspotoutdoors.com/forum/ubb...tor#Post2509840

When my hot/cold temp actuator went out, it just blew hot all the time.

Maybe yours isn't quite to total failure yet.

Worth checking on anyway.

[Jeremy airjer W]

iam thinkin a head gasket maybe?

You would be low on coolant and it would start to overheat. Since a head gasket will push exhaust gas into the cooling system the displaced coolant has to go somewhere. Some will get sucked in to the cylinder and some will get pushed out the reservoir. Eventually the engine has to overheat from the lack of coolant and/or the addition of combustion gases in the cooling system.

With that said the cooling system can appear to be full but since the heater core is the highest point in the cooling system if there is any air in the system the heat is the first thing to go.

[hanson]

I'm sure Airjer is on the right track.

4-5 years ago, I also had heat issues (no heat in the winter) and had assumed a thermostat was the problem. When I brought the truck in, they told me I was low on coolant and the water pump needed replacing. That did the trick.

[Fishinguy40]

You may want to disconnect and purge your heater core to ensure that it is not plugged. You would suspect that you would not have heat all of the time but you never know.

Also, you mentioned that you had a leak at one time. I had a 99 Blazer that blew only cold air. Turned out that the heater core needed flushing due to the Dex-cool. GM Dex-cool and air do not work well together. If the system ever gets low on coolant and air enters the system, Dexcool has a tendancy to turn into little gummie bears and clog everything up.

[hunterpete]

THanks everyone, very helpful information, if i get sunday off i will be doing some more looking.