So, a couple of months ago, I fixed my headlights. "Good" I said, "one problem less". Of course, next day, the A/C refuses to give cold air...
It took me two sessions of wrenching to get it back.
Engine stopped, but key in run I could hear the solenoid engaging the A/C. While driving I could feel the load of the compressor on the engine (change in RPM/noise). So I knew:
- my compressor is good.
- I have enough pressure
- The fuse is good
dropped the ducts, and checked voltage on the blower motor: 0V
unmount dash, and remove A/C controls. Umount the A/C / heat switch, and take it apart. It was like the headlight switch: after 15years, the copper tracks are covered with a black residue from all the sparks, and don't conduct electricity. Cleaned the switch tracks, re-assembled, reinstalled:
Rats, still no blower (I could get heat though)
Took a voltmeter, and measured:
- 12V on the white wire entering that switch
- when A/C on, 12V on the thin green/black, and on the pink.
But on the fan speed control switch: 0V
(the twin brother showed 12V when heat is on)
Tested for open in the resistors (driver side rear of the duct) : nope.
The A/C control module also looked OK (black box close to accelerator pedal on rear of duct too).
I finally found that it was the relay (blue cube of 1"x1"x1"). That relay is just hanging in the middle of the wiring on its plug. Replaced it (Kragen:$20), re-assembled:
and now, my A/C is back !
One last detail: when you pull out the A/C controls, chance are that you will unconnect one of the two thin vacuum lines that connect to a silver cylinder about in the middle bottom of the dash. Don't forget to put it back after reassembling the dash.
Good Luck to all.