My HVAC controls stopped working this morning. The vent selector moves but the air continues to come thru the defrost regardless of the selected position. Haven't had this unit out and I have a general knowledge of cables and electrically activated HVAC controls. All help and horror stories welcome. Is it most likely the control unit or failure of something else? Thanks!

 

I'm going to suggest listening really closely for a hissing sound when it is set on something other than defrost. It sounds like the vac. connections on the back of the selector switch (for lack of a better name) are leaking. So, that's my vote. I've had problems there before on two different thirdgens. If you look on the back of that selector switch, there is a multi-hose connection. If I remember correctly, it is held on with some push on style nuts or washers or whatever you would call those things. You can take those off so you can unplug the connector, clean it up, put something on to help it seal, and put it all back together. Let me know if that helps.

 

Thanks I'll check that. Wasn't sure if they are vacuum or electrically operated. Thanks!

 

As mtccl suggested, check the vac hose connection (a GM parts man once told me to swab the plastic tubes that slip into the hose connection with Vaseline for a quick fix). My problem was the switch itself. A simple replacement and I was good to go.

JamesC