This is a little long, but I wanted to give as much detail as possible. This is on my 92 pickup, which GM decided to use "electronic" controls for the HVAC system. When I got the truck, It wasnt working right- P/O said it might need a recharge. But when I checked the pressure, there was plenty of freon inside! So then I was clueless, cause the display would would blink AC- something was causing the relay not to work right- When I took apart the dash, i noticed that the old control display box had some signs of burnt circuit-, so I cleaned it up, added some fresh solder, some dielectric grease... and voila it worked-. FOR A LITTLE WHILE! It only works for about 10-15 minutes and then dies! It seems to work just fine at idle- Just after you drive it for a while, it just stopps working! Once it stopps working, there was only two ways to reset it- unplug the box, and plug it back in, or disconnect the battery. This seemed rather odd- in addition to that, I was getting an extreme voltage drop recently whenever I tried to use the Fan or Ac- the whole dash would dim, the gauges would read funny. Feeling that the box was the issue, I replaced the control box. I put in a new control box, and let the truck idle for 30 minutes- the AC worked flawlessly-. However, driving it on the highway, the same "flashing AC" came back up. No voltage drop issues however. What could this be? Is there some sorta relay elsewhere that isnt releasing or getting stuck? HELP!!!!!!