constant heat!

[turbotyphoon69]

Hey guys i have had this problem for a while, but with this hot weather i just cant take it. it seems that my heater vents are always blowing HOT air even with the settings on cool, and the ac doesnt blow cold air, but it is charged and all. The cab i always HOT for some reason and i cant figure this one out.

 

[SY2455]

Re: constant heat!

It sounds like a vacuum problem as all of the a/c-heater control are vacuum operated. Have you ever replace the selector switch? Have you check all vacuum lines and check valves?

 

[turbotyphoon69]

Re: constant heat!

the vac lines are fine, i put in Ians kit not too long ago so, im sure thats fine, What do you mean by selector switch?

 

[SyTyJedi]

Re: constant heat!

the vac lines are fine, i put in Ians kit not too long ago so, im sure thats fine, What do you mean by selector switch?

There are additional vaccuum lines under the dash. You can find a diagram of these in the service manual or Chiltons type book.

 

[VermontTy]

Re: constant heat!

Check the hose that feeds your whole heater system. If that isn't it, pull your heater switch assembly out, and on the backside there will be a plug with about 8 vacuum hoses that go to it; make sure that's connected.

 

[critical]

Re: constant heat!

I have the same problem. brings new meaning to "hot box"!

 

[jwaller]

Re: constant heat!

bypass the heater core during the summer, it will make the ac work better anyway.

 

[syclone73]

Re: constant heat!

with your a/c turned on max let it run a few minutes .check to see if your accumulator (big round silver thing at a/c box on firewall) feels cold. should actually start dripping water off of it after couple of minutes. next check to see if blend door switching from hot to cold.

 

[turbotyphoon69]

Re: constant heat!

havent got a chance to tear it down yet but will check all of this things listed above! thanks

 

[SY2455]

Re: constant heat!

the vac lines are fine, i put in Ians kit not too long ago so, im sure thats fine, What do you mean by selector switch?

The selector switch is the one on the right side of your Air Conditioning Control Unit, when you remove this panel you will find a vacuum operated switch with 6 ports on it if I remember correctly, the replacement cost was like $18.00 at GM. Recheck your main vacuum line feeding the cab and test for vacuum at the switch. The other thing you might check is your temp control cable, this is on the left side Air Conditioning Control Unit. On my truck it turn out the above switch was bad.

 

[VermontTy]

Re: constant heat!

The selector switch is the one on the right side of your Air Conditioning Control Unit, when you remove this panel you will find a vacuum operated switch with 6 ports on it if I remember correctly, the replacement cost was like $18.00 at GM. Recheck your main vacuum line feeding the cab and test for vacuum at the switch. The other thing you might check is your temp control cable, this is on the left side Air Conditioning Control Unit. On my truck it turn out the above switch was bad.

With the truck not running, you should be able to move the selector from defrost, to heat ,to vent, etc and hear the air / vacuum moving stuff; although it's not running and drawing vacuum off the engine, it still has the tank to draw from. If you don't hear a "hiss" everytime you move the selector, you've got some kind of issue on the feed to the selector.

 

[Ian Turgeon]

Re: constant heat!

Pull the back of the glove box out, behind the vent tubing you can see a lever on top of the ac box, this is directly linked to the heat mixing door, if it isnt moving when you move the hot/cold lever then your problem is exactly that.

The heat isnt controlled by the vacuum at all, just the doors that direct where the air goes and where it comes from