No heater at idle?

Hello,

This sounds like a typical problem these vans had which is they get air trapped in the heater core which makes it difficult for coolant to enter the heater, This is why it only works when the engine is revved.

I would make sure the coolant is full then start the engine and turn the heater on full blast. Then raise the rear of the van as high as you can used a jack. This should allow the air to "Burp" out.

https://www.2carpros.com/articles/jack-up-and-lift-your-car-safely

I have seen them do the front as well FYI.

This guide can help as well

https://www.2carpros.com/articles/car-heater-not-working

Please let us know what you find.

Cheers, Ken

Thanks for your response. The coolant has been flushed twice. First time when changed thermostat, and second time when i Flushed heater core. The coolant level in the reservoir is where it's supposed to be when cold. I think that vehicle does not use vacuum operated controls. they should be electrical. When i switch from cold to heat and other way around i can hear the actuator switch.

I can check the vacuum on the engine using my vacuum tester and let you know. Let me know if you have any other suggestions.

Thanks,
Alex

Also, does heater core plumbing have bypass hose? this can be a problem with core flow as it allows flow to bypass.

How about a simple, "feel the hoses" as the enter the firewall into the heater core.

If they are really hot at normal operating temperature, and cool air is being blown out of the heater inside the car. Something inside/on the heater box is malfunctioning.

That is, if it is not bypassing, like fixitmr suggested in his link.

If a heater hose is crimped or twisted, it could inhibit flow also.

Keep us posted.

The Medic

Thanks for your help guys. Great site by the way. Okay, got some very good news but before i go into it i will answer your questions.

No bypass hose or heater control valve on this car. The only hose coming of heater core outlet goes to the throttle body cooling line (this throttle body needs to be cooled with coolant).

Both hoses coming into the firewall were cold until you rev and hold 2000 rpm. then they become warm to the touch and then after thirty seconds back to normal room temperature. so my solution so far. :)

It seems that there was air trapped in the system.

What i did:
Took it for the twenty minute drive. It would only start heating at about 2000 rpm. Once it goes down, no heat. ( i am in Canada and it is -20 today. :)

So came back to the garage and decided to "burp" the air from coolant reservoir while the car was hot and thermostat was open and jack up the car like you said.

I know that this is not very good idea because it is under pressure but i did it slowly . While releasing the pressure i noticed that coolant started rushing back into the reservoir trough the overflow line but it was not steady flow (air was coming in). Once the car cooled down i noticed that now I have less coolant than before I drove it. I thought it was a good sign since the air has been pushed out from the system and in its place now we have coolant.

So started the car and it started heating as it is supposed to at heat on idle. I repeated this same test next morning and again got the heat almost immediately after start-up.

I have heat. Let's hope that it stays like that. I have another question related to my alternator but I will ask that in another thread.

Thanks again for your help.

Glad you could get it fixed, that kind of problem can be tough. Please use 2CarPros anytime we are here to help

Cheers, Ken

No hot air while on park or while the vehicle is not moving. But get hot air as soon as the vehicle starts moving/driving

yes, Coolant reserve tank was empty. Thx for the tip. now i need to check why/how it got empty ?

have apro pressure check system it may be a head gasket leaking internally

How to bleed air from heater core.

run motor at 2500 rpm till you get heat. make sure the level is checked often

Roy