75' heater/ac controller...help!

[randylindberg]

I'm curious if anyone out there has rebuilt the ac/heater control unit in the center console? Or, if anyone has a used one they're willing to sell. I have a 75' coupe with AC that has a questionable controller. I'm not much of a mechanic, but when I took it in to get the AC working again...the estimate was HUGE! My controller is supposedly not working correctly to get the AC blowers to work and my mechanic recommends I replace the controller and that should solve the problems. Ebay hasn't brought the magic part yet...anybody got any suggestions?

 

[Roy]

Heater/AC Control

There is a local salvage yard with a heater/AC control for $50 to $80 - I forget which.

Chances are you can fix the one you have.

The control consists of a rotating slide that delivers vacuum to the various devices to activate them. The defroster valve flap, for example, is pheumatically operated by the control valve when you slide the setting to "defrost". Even the temperature of the heater core is controlled pheumatically as the control opens and shuts the water valve in the engine compartment when you move the controls.

Sometimes, the small hose feeding the device being operated becomes damges and no longer operates the device. Even worse, a damaged and leaming vacuum hose decrease your engine performance because it robs valuable vacuum from the engine intake function, not to mention the dozen other devices operated pheumatically.

Note to worry, just remove the heater/ac slide control and inspect the back. Sometimes a hose has slipped off, sometimes one of the two holding screws have broken off and allowed the rubber connector containing the small hoses to come loose. If you have good lungs or a vacuum tester, you can connect it to the individual hoses that feed the various devices and determine if they are working and/or there is a break in the vacuum line.

Hope this helps more than it confuses.

 

[mike weyman]

when i was buying parts for my 75 , the guy told me to check it first and save $$$ cause its almost always fizable. all the used ones he had , he fixed himself. mike

 

[mike weyman]

yes i know fizable is not a word.typo

 

[KenSny]

When you really give up and can't find a used one. Try the parts places. Eckler's, Corvette Central, Zip, etc. I actually got mine working again when I repaired the console gauges. I actually had AC for about a month then nothing. Guess the R12 is gone now and that's a bigger problem. Here in northern Ohio I can do without the AC I guess.