1976 F-150 factory air
 

My '76 150 w/factory air needed charging. Put a new dryer and new service valves on. Compressor is good. Took it to be charged but the man says the compressor won't run. The vent and defroster doors didn't work right anyway so I got an AC and heater vacuum switch from Carpenter. installed it on the heat/AC control panel. The doors all work now but still no compressor, not even on defrost. I am begging for help. The man charging it says to toggle the compressor. I want to avoid that. Thanks in advance.

Did you already put refrigerant in it? If so, it didn't kick on once you started to get pressure? If there is refrigerant in it, what do the high and low gauges read? Is the wire coming off the drier hooked up?

The guy wouldn't charge it. He hot wired the compressor to make sure it worked. There is no wire coming off of the dryer. Thanks.

Hmmm, my drier has a safety switch with a wire. The compressor won't turn on without the wire hooked up on mine.

Does your compressor turn by hand?

I'm not sure what it would hurt to try to put some refrigerant in it. Is it r12 or 134? Someone else here might know why you wouldn't want to try to charge it, but I say give it a try and see what happens. It definitely won't turn on without any refrigerant charge.

Yea, the center turns by hand, it just won't engage. I'm going to go to 134. I thought the compressor would run on defrost without Freon but maybe not on mine. Square one. Thanks for your time, I REALLY do appreciate it.

Wait, wait... are you saying you are getting no air blowing out the vents or defrost vents? That is just the blower fan. That's located in the big black box on the passenger side of your engine bay. You should be able to turn that on regardless of whether the compressor is running. In order to get cold air, you need the compressor, refrigerant, and all that.

What did you buy from Carpenter, D5TZ-19B888-A A/C Vacuum Control Selector Valve Assy that is located on the backside of the A/C heater control panel that all the vacuum hoses connect to?

If so, this valve also contains the "kicker switch" that turns on the compressor.

NO. The blower works on all of the speeds, the heat/AC controls operate all of the doors. The compressor just won't engage on COOL or DEFROST.

Answer my question in post #7.

Yea, that's what I bought. Made all the doors work but no compressor. It has a 3 prong male plug on it. It IS plugged in. I've traced wires till I'm dizzy. BTW, glad to hear from you. I know you know your stuff. Thank you.

Is this wire hooked up on yours? If yes, then put some refrigerant in it, it won't turn on without pressure. If not, hook it up, then put in the refrigerant (don't forget the correct oil if it has none).
https://cimg7.ibsrv.net/gimg/www.for...90c677020c.jpg

There's a switch on that valve that turns on the compressor when you slide the lever. You hear a CLICK when the compressor turns on.

If the compressor won't run, it could be the field on the clutch. See 2987 in pic.

D4AZ-2987-A .. A/C Compressor Clutch Field (Motorcraft YB-162) / Marked D4AH-2987-A1A or A2A / Obsolete ~ Available NOS & from auto parts stores.

1976/79 F100/350 all V8's & 1978/79 Bronco // 1974/78 LTD except with swash plate compressor.

https://cimg4.ibsrv.net/gimg/www.for...d5a3bab9a6.jpg

Mine is a little different. There's a long wire coming out of the compressor that plugs into the wire from the dash. We know the compressor is good by hot wiring it. I may ask him to hot wire it to get some Freon in it and see if it will go ahead and work. I apologize to everyone. This is my first listing. I'm almost 72 and have NO business messing with this. It's a project I should have run from. I just want to get the AC working and find it a home. THANK ALL OF YOU VERY MUCH!

If the field was bad, would it still run "hot wired"? Thanks.

If everything is stock the charge isn't required to cycle the clutch in. the system doesn't know or care since it has no binary switch.
c.
Check and see if you have power to the clutch, maybe your mag is shot. if you don't have power start working backwards and find out where it is or isn't.

You also have a cycling switch in the heater/evaporator box . if it's bad or the wires are unhooked it will halt the power.

It will cost more but when you get it charged I would use R12 as the system was designed for. it will make your system last longer with it's much lower pressures and it will cool much better as well. r134a is a cheap alternative but a poor one.