Trying to get my A/C working

[Bill-W]

This is my first diesel pickup, I bought it in March, I've been working on marine diesels since I was a kid and have been lurking here for a few months reading all the posts I can, the site has already saved me a bunch of $$$ and in my future projects also I hope to be contributing as I figure things on my own truck out.

I was trying again to get my A/C working on my 88 F250 today. I have pressure in the system, not sure how much as I do not have a R12 gauge, but the pressure switch is not kicking on. I was going to try and replace it tomorrow if I have time.

I shorted out the pressure switch and the compressor clutch kicked in, so I fired it up and overrode the switch running at idle, no bad noises were made, and I could see the clutch engage and dis-engage when the pressure switch was by-passed. I could not feel any cooling and none of the refrigerant lines got cold at all. After a minute or two I shut it down, I did not want to destroy anything, the compressor clutch was very hot , the compressor and belt were not.

I am thinking the clutch might be shot, or would it be the whole compressor is frozen and the clutch is slipping and overheating? Can I replace just the clutch and not have to discharge? I'm thinking pull-a-part right now. I'm hoping the system is still filled with R12 and I do not have to evacuate it as I don't have a lot of $$$ to dump into the A/C right now, I've got to do my injector return lines first!

 

[NJKen]

The part of the clutch that pulls in on the front should turn by hand (with moderate resistance). If you cant turn it for anything the compressor may be seized up. When it pulls in it should spin with the pully. Excessive heat in a short period of time is not really good. Since the compressor clutch engages when you jump the cycling switch it is most likely low on charge. Those switches do fail but not at a very high rate. Yhe best thing you can do is try to pick ip some kind of cheap pressure gauge. If you push the schrader with your nail you should be able to tell if its high or low pressure. Under a hot hood there should be a static pressure of about 100psi with the ac off. Unfortunatly if you have to change the compressor you will loose all your freon. If the compressor is toast you (at a minimum) will need to change the accumulator and orifice tube. You should also flush the condensor
Lets not put the cart in front of the horse yet though.

Post back and let us know if the clutch hub spins and how the switch works out for you.
Ken

 

[Bill-W]

Well I did not get around to getting a new switch or pressure gauge today, just had too much other stuff going on. I did however pulled off the belt played with the clutch. When it is not engaged the pulley turns free and the center turns OK also with a little resistance. When the clutch is engaged I can barely turn the pulley or inner hub. I guess I am lucky I did not get a face full of shredded belt yesterday, I'm surprised there was even enough friction on a single v-belt to turn it.

Would this be the compressor is locked up or the clutch is toast?

If I have to crack it open and cannot use the existing charge I am thinking about junkyarding a new compressor and clutch, as money is tight, pull-a-part with a warranty. Looks like I should add an new accumulator and new seals. Should I go with R134 or find someone to re-fill with R-12? Any idea on what is a decent price for someone to pull out the R-12? It should be free!

 

[JPR]

With the clutch disengaged, the pulley should be free spinning. With the clutch pulled in, there should be a reasonable resistance, but not too hard to turn.

Sounds like the compressor is toast.