Help! Heater not blowing hot air - 95 Vet

[stzvet]

;helpWhen you set the interior temperture settings above outside temperature, the heater will not blow hot air. The A/C works fine and the vent selection works fine. I had a local Chevrolet dealer look at it and they cannot find the problem. The heater hoses get hot but it seems that the system is not letting the door open to the heater core to warm the air in the system. The vaccum lines are all good.
Has anyone had this problem? Can you give me some ideas?
Cold & Frustrated!!
Thanks
Steve "The Wolf"

 

[93Rubie]

Can you hear the blend door moving at all when you change the temperature? Or airflow change in the ducting?

I'm not sure on the 95's but my 93 has either a manual cable operated blend door or a electric operated door. What is yours? Electronic Climate Control or Manual.

If it is vacuum controlled the blend door that is, it can be tested for proper operation with a vacuum pump.

If that is in proper working order, then I suspect inadequate coolant flow through the heater core. Might need flushed out, or if really bad replaced.

Just because the heater hoses are hot doesn't mean crap. I had my butt handed to me by a Taurus with lack of heat concern. The hoses where hot, but not quite hot enough. Blend door worked so, I flushed the heater core. Still didn't work correctly, car ran normally, turned out it needed a water pump, yes a water pump. The impeller was ate away. The cooling is good enough in Taurus 3.0L V6 engines that the natural laws of thermodynamics keep the coolant moving enough in the engine to keep it cool, but not enough to have heat in the cabin.

 

[John Robinson]

Vacuum Check Valve for Cruise and Heater

This is the Check valve that controls the vacuum to the heater and cruise. You should be able to pull or suck on one of the smaller connectors while holding a finger over the other small connector and there should not be any air come through the larger discharge fitting.

If this is bad get the OEM part I tried the auto store ones and they do not hold up and besides I think it was only about $10.00 for the OEM.

http://farm1.static.flickr.com/105/290560320_79fb23d3ab.jpg

http://farm3.static.flickr.com/2115/2223853353_ddc2223653.jpg

 

[gmjunkie]

This is the Check valve that controls the vacuum to the heater and cruise. You should be able to pull or suck on one of the smaller connectors while holding a finger over the other small connector and there should not be any air come through the larger discharge fitting.

If this is bad get the OEM part I tried the auto store ones and they do not hold up and besides I think it was only about $10.00 for the OEM.

http://farm1.static.flickr.com/105/290560320_79fb23d3ab.jpg

http://farm3.static.flickr.com/2115/2223853353_ddc2223653.jpg

It don't matter if it's Electronic or Manuel AC,they both have it and need it to move the blend door!

PS. You got it backwards John! You should be able to draw air through larger one,but unable to blow air back through it!!

 

[John Robinson]

Call Me Backwards

Junk I could not remember what you told me about how to check the valve. Spent an hour looking at the FSM and no answer so I just guessed on which way it worked.

I have a new problem that I am going to post and hope you can give me some help.

 

[vetteoz]

If it is vacuum controlled the blend door that is, it can be tested for proper operation with a vacuum pump. .

Blend door is a elec stepper motor controlled by the A/c head unit
The vac goes to the pots that control vent operation only through this unit

 

[93Rubie]

Blend door is a elec stepper motor controlled by the A/c head unit
The vac goes to the pots that control vent operation only through this unit

That is exactly what I thought, that the mode doors where vacuum operated, my FSM shows blend door operation via manual cable or electric stepper motor.