Heater problems. Help!!

[rocknrone]

My heater is only warm when the car is in motion.

I warm up the van and the temp guage says normal temp.
I turn on the heater and it blasts cold air, like it's comming straight in from outside. Doesn't matter if it's on recirculated or fresh air.

As soon as I start driving warm air starts comming out.

When I stop at a light in traffic it immediatly starts cooling down until I start moving again.

I changed the thermostate without success.

Any thoughts?

[rockwood84]

sounds like the air mix door is stuck open

[stupid friend]

Hi, I'm new to this forum. I am a member of another forum, that has helped alot. I am having the same problem with my wifes 02 venture. My question is how do you go about getting to the damper when I open the hood I get discouraged with the lack of room and I close the hood and go in and turn on football. PLEASE help, she is threating to start driving my pick-up till I get it fixed!!

[463]

# of things to look at 1. coolant level (should be full to the cold line when eng is cool and red if you use dexcool) 2. is the rad cap good for a psi of 15 lbs (test or replace) 3. are the rad hoses in good shape. it's a good chance #1 or #2 are the suspects. As soon as you start driving warm air starts because the coolant psi will increase or the coolant will move with a rpm increase. because i detest autos the don't work right. 463

[stupid friend]

Thanks 463, I have to lean more towards what you say, cause if the damper was open the temp would stay the same. I'll try that before she finds the keys to my truck.

[463]

stupid friend: i forgot to wellcome you to AF it" a good form. this happened to me two years ago. i had low heat in the olds van. the gm service mgr and i felt that it was the "t"stat so i said change it and the tech said the computer showed low temp(cause it's a pain to change,easy way is to swipe and sign $115 later and it's out of the shop). so i go for a drive and all is good pull into the gm service lot and the van temp gauge falls down right along with the warm air (heat) so i went home and tested the rad cap and the psi reached 12 to13 psi. so a new cap tested to 16 lbs and installed ad a road test and all was normal (and still good heat today). so one more step to do. test the old stat and found it opened at the 195 f as it should, and i did go to the teck and gm service mgr to point out my findings and got a bit of personal satisfaction for my self. just wrote it off to education $115.00 education.

[rockwood84]

the way to the damper and connections is under the passenger side of dash remove the kick panel by prying out the tabs. also these vans with 3.4 have bleeders in the cooling system one is above the water pump on the metal heater hose. the other is on the thermastat housing. loosen the little bleeder until coolant comes out then tighten back up. one thing i have found out about thermastats is to get one made in the usa ,the ones made in mexico will not open even if you drop them in boiling water. the radiator cap will cause you not to have heat by not holding pressure on the coolant. ,also a thermastat stuck open will also cause no heat.but stay away from the ones made in mexico as the thermastats are a pain to get to .good luck