Heating issues

[Koscoe]

Good afternoon all,

I have a 2002 Venture with some strange (to me) heating issues. The van warms up fine, but it does not have heat until you drive. When you come to a stop sigh or red light the heat blows cold and goes back to warm when you start driving again. Has anyone ever heard of this?

[aleekat]

Low on coolant?

[woscarr]

I had a 1998 Trans Sport (same body as Montana) that had the same problem. Drove beautifully, so smooth and powerful, awesome a/c just too bad about the body.. Rusted big time !

Drove that van for almost 8 years and over the years we noticed less and less heat in the winter ! Got so bad we had heated seat pads and a little heater in their, the last winter it could barely defrost the windshield here in Ottawa, Canada ! Brrrrr (summer & winter) and great ! ride is what I remember of that van.

At first I started investigating a possible hot/cold air circulation door being stuck but I dug into the dash a bit behind the glove box and ruled that out.

Although I never repaired it before I finally parked it for good my money is on blocked/almost finished heater core. That ol' 98 of mine never showed any signs of intake/head gasket issue, just drove beautifully, but would barely put any heat while driving and it would go cold when you stopped !.. I have a 2002 Oldsmobile Silhouette now (no heat issues, needs a a/c line replaced tho.. rear one, doing it soon).. Love it !!

Good Luck

[rhandwor]

Originally Posted by Koscoe

Good afternoon all,

I have a 2002 Venture with some strange (to me) heating issues. The van warms up fine, but it does not have heat until you drive. When you come to a stop sigh or red light the heat blows cold and goes back to warm when you start driving again. Has anyone ever heard of this?

You may have an air bubble in the line. Try putting a floor jack under the front of the vehicle. Run it for a while and see if this helps.

[Tech II]

Air pockets are caused by coolant leaks/head gasket problems......

When you come to a stop, it gets cool? What happens if you put it in neutral and rev the engine? If you get heat, sounds like the pocket is small and the added rpms of the pump can force the coolant through the heater core.....

So two possibilities here....a small coolant leak creating an air pocket, or a partially plugged heater core....

[Koscoe]

There is coolant. We have had this in the shope for some overheating issues in the past month or so. Our mechanic finally replaced the thermostat and some kind of fan relay. Now it doesn't overheat anymore. I will have to try the nuetral idea to see if this changes anything. There could be air in the system and I don't think the core is plugged since we have had it flushed twice. I have just never heard of this happening before so I am confused. I will report back when I have reved up the RPM's. Wish me luck.

We are going to start looking around for a different mechanic becasue the quality of work has started to decline in our usualy shop. We have known this mechanic for almost 18 years and its terrible to start going somewhere else, but can't keep dumping money into the van without getting good results. He also lied to me about breaking my trucks hood release handle inside the cab. He said it was broke when I brought it in. I know he is lying becasue I replaced this piece when i bought the truck.