HVAC Control Quit Working

[Joe Dozzo]

The HVAC controls - such as they are on our beloved Vipers - have quit working on my 98 GTS. Unless of course one considers cold air thrown through the defroster ducts more desirable than the usual locations - the only option currently functioning on my car.

I've also noticed a slight anti-freeze smell in the cockpit, but can find no obvious leaks either inside the car or up front in the engine compartment.

I'm sure there is a selenoid somewhere - vaccum or electronic - that's disconnected or just plain failed. Any one "been there and done that" before?

(JonB, if you're out there, expect a call when I find out where the little bugger is!)

Thanks!

 

[shifter]

Defrost only is a safe mode for the A/C system. If you still get temperature modulation but can only get the air through the defrost, your mode door in the A/C unit isn't working. Normally this is due to a vacuum leak. Check the vacuum lines from the actuators on the evaporator/blower unit under the hood. Look for damaged/melted lines. If you don't find anything, I'd remove the A/C control head (bezel just "pops" out with some care) and the A/C head unit has 2 screws I believe. On the back of the unit you will see some vacuum connections, ensure they are all O.K.

You have a vacuum leak somewhere.

 

[ACELLR8]

Joe,

I had the same problem with my 95. When the vacuum is not working it automatically comes out of the dash. I learned from Chuck Tator that the vacuum source for the system is on the back of the engine, on top of the manifold on the passenger side. Probably only vacuum line there.
Did you have a stereo put in lately? There is a lot of vacuum slack in there that can get kinked and the extra wire from the stereo head unit when pushed in can break one of the plastic vacuum lines on the controler unit.
Turned out that was the case in my situation. I removed my head unit and found the vacuum source coming from the engine and going up to the back side of the selecter or control knob. It turns out that the main vacuum feed tube was broke where it goes into the selecter. In my case I just replaced the controller unit and everything worked ok.

It is a little difficult to explain on the board. If you want more specific info than what I provided, you can email me and I will give you my # to call me. Which might make it easier to explain. There is a couple of other things to look at as well. My initial guess would be a vacuum problem, or the controller is bad. The vacuum lines are pretty easy to trace once you get back there and are color coded as well.

 

[Joe Dozzo]

Thanks both Joe and Ed.

I think Ed may have it... Back in March car was at the dealership, was broken into and the stereo stolen. I doubt they were careful. Since I had already replaced the factory unit myself, I think I know exactly what you're talking about Ed, again, thanks!

I'll also check vaccum line at engine, but it doesn't run like there is a vaccum leak.