I have a 88 f150, and it has an AC compressor that won’t turn on. I know this usually means it’s low on R-12 from a leak, but with the regulations on that stuff I’m hoping it’s not that. Is there any other thing that can cause this I can look into? If not it’s gonna have to go to a shop to get a 134a conversion put on it. But will shops even handle the R-12 to take that system out?

 

Check to see if you have 12V+ on one side of the low-pressure switch which is on the accumulator on the passenger side under the hood. If you do have 12V+ on one side, jump it and see if the compressor engages. If so, either bad switch or low on freon.

 

Will this still work without the engine running? Or will there be some noise when the compressor engages? I can’t start it right now.
when I press the AC switch in the climate control it doesn’t light up either. Could be a bad bulb. Don’t know if that gives anymore info.

 

Turn the key and the a/c on. If the compressor engages, you will hear a click.

 

You could also start the truck up, turn the a/c switch on, then disconnect the low pressure switch and jump it with a paper clip...if compressor turns on, you're either low on freon or the switch is bad (probably the former).

 

Umm…. How to jump the low pressure switch covered in post 2 and the OP stated he has a non-running engine in post 3.

 

ugh, it's been a long day...must have scrolled right past that and missed it...my bad

 

I’ll try it this weekend when I fix my water outlet leak. But I still won’t start it because I’ve got a new PS pump in and I still need to flush the system.

 

You can and should flush the system without starting the engine. We now return to our regularly scheduled program.

 

If all other checks and are in good condition make sure that there is no more than .025 clearance between the clutch halves. Too much clearance will not allow the clutch to engage.

 

I just wanted to add that the clutch coil would still pull on the clutch disc and it would be attempting to engage the pulley.

Depending on the factors, compressor lockup may occur, noises and/or a brake-burning-type smell could also be present.

In the few encounters I’ve had with excessive AC clutch air gap, it tends to result in a pinging or squealing/whistling type sound; it’s also usually a symptom of other AC system issues that cause the compressor to work harder.

 

Agree, Last summer the clutch on my Sport Trac would disengage due to excessive clearance. However it did not make any noise. There was enough shims that I removed to tighten it up.

 

So I tested it. With the blower motor on low and the ac switch turned on the climate control panel it has power 10-11v. And when I jumped it the clutch engaged.

 

Just for kicks check the clearance of the clutch halves air gap.

 

How would I properly do that? And how would I tell if it’s the switch or the Freon? And why didn’t I have battery voltage there? Is it referring to the switch on the climate controls or something else?