So, I just finished replacing the head gasket in my 1992 pickup (22re) for the second time. First time 180,000 miles, this time 268,000 miles. Everything went well, except now my A/C compressor won't kick on. Before the head gasket replacement the A/C worked, but at idle or slow RPM's it wasn't cold. At highway speeds it was ice cold. The truck was down for about one month total after the head gasket blew. It was right before Christmas so I waited a while. When I did the head gasket I just pulled the intake over to the side (plenty removed). Any idea why the A/C won't kick on now?

 

Well, hate to ask the obvious, but is the wire connected that goes to the clutch on the AC? Pretty sure it snakes across from the fender down to the AC compressor right under the intake there, and seems like something that could easily become disconnected. Also one other thing, do you have the AC idle up VSV connected and working? That VSV should kick up your engine idle when the AC is on, and perhaps you don't have that function working....and if your idle is too low and not allowing the AC compressor to kick on.

Assuming the wire going to the clutch is there and connected and the AC idle up functionality is working, there is an AC amplifier up on top I think of the evaporator box behind the glove compartment. It is possible if your idle changed, that maybe you have to adjust that AC amplifier to kick in the compressor at a lower RPM, it has a little knob on it for adjusting it, I would read thru the FSM before messing with it though and I would check the other items first before I even considered touch the AC amplifier.

 

The wires appear to be connected , and the vacuum lines appear to be connected properly. but when I push the button to turn the A/C on, it does nothing, no idle up, no click, no nothing.

 

Low on refrigerant?

 

The freon may be just low enough to not trigger the system. Could also explain why it wasn't cold at idle before the headgasket failure.