The high speed fan of my HVAC has not worked for about a year. I decided to fix it this week. I first checked into replacing the control panel and found that mine has an extra button for rear window defrost. According to two local salvage yards, these control panels are Astro specific and hard to find. I took it out thinking maybe it could be fixed. Of course it is a sealed switch. I figured at least I would test it to the wiring diagram. That's when I discovered my '98 has a circuit board and relay combo and the high speed switch actuates the relay. Found this little monster in the front of the HVAC box after removing the wiper/coolant reservoirs. The new one from O'reilly's ($57) was different and needed a larger hole in the HVAC box. I scribed and enlarged the hole with a razor knife. The new one is now installed and all four fan speeds are operational! Whew . . .
