Heater doesn't blow heat

[VaeVictus]

Thermostat seems to be working fine. Not quite sure why it wouldn't blow warm. Any suggestions?

[mjparme]

I had a car once where the heater core got clogged up. Maybe try to flush the system?

[GrigoryRasputin]

the vents may not be shifting correctly to get hot air... may be permanently stuck on vent or something. Check vacuum pressure.

[HBHRacing]

the blend dore is controled by cable not vacuum. Get your head down under the dash and turn it from hot to cold a few times and see if you hear the door move. it;s probably your heater core. feel bith heater hoses, if one is hot and the other is cool then there you go

[GrigoryRasputin]

Originally posted by HBHRacing:
the blend dore is controled by cable not vacuum.

Are you sure???

[Pastor Larry Roques]

I am....I've heard that little door open and close on numerous occasions when I was checking out an AC problem I was having. Pretty sure its a cable. The vacuum systems you refer to are mainly on upscale vehicles (Caddy, Lincoln, Lexus,etc ) where true adjustable thermostat and digital controls are in place. Our cars are really grassroots in that department. I'd believe that it was a coolant flow problem or even an air bubble in the system somewhere.
Blessings! [img]graemlins/wavey.gif[/img]

[HBHRacing]

Originally posted by GrigoryRasputin:
</font><blockquote>quote:</font><hr />Originally posted by HBHRacing:
the blend dore is controled by cable not vacuum.

Are you sure??? </font>[/QUOTE]yes, The mode selector is vacuum controled. the blend door or "air mix door" is cable operated. GM systems are usualy 1 of 2. cable or electrical actuators

[GrigoryRasputin]

I had a broken vacuum tube once and the air wouldnt change which vents it came out of until I fixed the tube...

[HBHRacing]

yes, but the mode door is different from the blend door. they are seperate components. That will not effect the ability to switch between heat and cold

[GrigoryRasputin]

Its kinda silly that they set them up differently. Oh well.

[HBHRacing]

they do that so that you can have an infinet adjustment with the cable. you can't do that with vacuum. it's all or nothing, unless they designed a regulator in the heater control unit for adjusting vacuum which would just be a pain in the but.