I have a 78 Caprice, suddenly the air stopped blowing, first I checked the fuses and they are OK, the problem is that the compresor do not engage and the blower do nor move, anybody can help?

relay, Mine went out over the summer. I dunno if it is the same on a 78 but mine was a little silver box right next to the blower motor.

It's the same on my 77. It's the rectangular box mounted via a metal tab with two screws on the top of the heater box. the You can try tapping on it to see if it'll free up, that may get you by until you can get another one. It's only about $15 new and I think one from any of the 77-90 caprice or impala will work.

Ok, I will check for the relay, also mine was converted because in Mexico original relays are not easy to find.
Thanks for the tip! I'll let U know how it worked.

Also, I just thought of this, there is a heavy red wire that goes through a black harness connector between the valve cover and the A/C coil box. Chech to see if you have voltage on the side of the harness toward the blower.

It also probably wouldn't hurt to remove the motor and clean the armature & check the brushes.