Hello. Have seen many great posts about no A/C, and warm air coming through the center vents. Lots of great advice too. I had a weird case and thought I'd share it.
Had the usual, above-mentioned probelms, that many folks seem to have. Following advice from this forum, I checked the water control valve. Sure enough! The WCV plug (at the base of the solenoid) was melted. After replacing the whole valve unit and a new plug, I fired it up. NOTHING! Still blowing warm instead of A/C!
Checked and rechecked all electrical connections. Figured the replacement WCV must be defective, so I got a clean used one from a junk yard. Same thing! I could tell (after driving) that hot water was getting into the solenoid because it was obviously hot. Finally, I let the car cool down overnight, thinking I'd pull the WCV and crack it open, and I found that when I grabbed the WCV (even though the car was stone cold) the solenoid was almost too hot to touch. No key in ignition. Really hot!
I checked the wiring diagram and tried replacing the Climate Control Module (they are about $40-60 used on Ebay). That did the trick. Everything works well now. Even when obviously bad, the CCM had all normal digital readings on the displays, but evidently controls the WCV by means swtiching off the negative current, leaving the WCV always connected to the positive, therefore causing the solenoid to heat up.
Anyway, I thought I might save someone else the time. If you WCV is really hot, even when the car is cold, bet on a bad Climate Control Module! BTW, the CCM is really easy to install in about 10 minutes!
Hope this helps someone else!