I'm unable to control the interior cabin temperature with the slide switch. Any position results in only heated air from the vents. Any thoughts on remedy/replacement switch?

 

Forgot to mention it's an '83

 

Do a search. Common problem. Either the heater valve, a vacuum leak from one of the vacuum pods preventing the heater valve from closing, or the mixing motor, pretty much in that order re: probability.

 

Have you checked the heater bypass/control valve. Vacuum controlled and prone to failure. Lots of info. Do a search and/or read the newbie thread.

Welcome. You've found the right place. There's a listserv, also quite useful.

 

If you will send me a standard email (not thru this system) I will send you a paper that explains the HVAC system.

techAT928gt.com - change AT to @

 

I have the same problem, I've done the first 2 bits, but sadly it looks like mine is the mixer problem.

First 2 are a doddle, so hopefully yours in one of the first 2.

 

As a temporary measure, you can simply loop the coolant line back at the valve (run a U shaped line between the two ends). This way you will stop the hot coolant from going into the cockpit.

 

Most likely is a sensor connection problem. The inside & outside sensors are in series - so check the ouside sensor in the LHS wheel well (in the alternator tube intake) first - its easiest and the most common to have issues.

You can also test the sensor loop in the console.. but it takes a little work...

Any sensor connection problem yields full heating.

Alan