1991 Buick Park Avenue - HVAC Controls Dead

[Teseract]

My wife has a 1991 Buick Park Avenue, 3.8L V6, 3spd auto w/overdrive, 234,000 miles on the clock. It has an issue with the HVAC controls, sometimes they work, mostly they don't. It has the manual controls (no automatic climate control).

When it works, the buttons light up and respond to presses, if it's dead, the blower motor won't run, it won't change from setting to setting for the vent controls, the A/C won't engage, and worse for this time of year, you get no heat and no front window defrost. The panel goes completely dead. Not even the rear window defrost button will engage, so all the windows fog up and you end up driving around in the cold with the windows down to maintain visibility. With two small children to toat around this is a bad situation, obviously.

It seems like a loose connection since it usually works intermittantly if you hit a big bump or take it into a corner hard. Is there a relay or common connector failure I can try to hunt down? In the summer it just meant sweating with no A/C, now it's turning into a health issue.

Thank you!

MattB