I replaced the AC compressor/clutch last night, pulled down a vacuum and it held -29#s for 30 min. Charged with 80z Ester oil and tried to start charging with 134A but it would not take the charge. The pressure rose up to 110# and the clutch never kicks on.

First question is the clutch wires, there is a green and black, it would appear that it only goes on one direction but I find that the black wire is on the top terminal and the green is on the bottom.

Is there anything that I am missing? The old clutch seized up and so I am going to check the fuses maybe when the old one locked it it blew a fuse.

Also does anyone know the capacity of 134A on a '82?

Got to have AC in Texas too darn hot these days. Also got to get ready for the Jets and Vettes show....

Thanks for the help.

 

On my 82 it takes 3.75 lbs R12. I put in R134 freon until my gauge reads 40 lbs at idle. Pull the plug off the low pressure switch on the accumulator and jump the wires, at this point the compressor should run and you can charge A/C. If not check for power and ground at the compressor. If it has a bad expansion valve it will not let you charge it.

 

You getting 110 on the low or high side?
Give pressures of both sides please.
charge 134 to 75% of r12 system capacity.
or as I was told along time ago charge with 134 till the accumulator start getting cold.
With A/C on and low press switch jumpered green wire at compressor coil should be hot

 

You need 85-90% R134 (of R12 amount).
The vacuum should pull the freon in & then start engine & charge from the low port.
What are the conditions of 110# reading?

 

I did not open the high side so I don't have any data regarding the pressure on the high side. I did pull the vacuum on both sides, but did not open the manifold because I have always heard that you should never charge through high side.

There is not a vacuum any longer because I charged with a small can of oil and so the vacuum is now pressure. As far as the 100# pressure. That is with the engine running, AC on max but no compressor engaged.

It seems like I need to jumper the low pressure switch from what I have read here and other areas. Where exactly is this located on the 82? I found another thread with a picture but not real sure exactly where it is located. I will check my FSM also.

Thanks again!

 

On my 77 the low pressure switch is mounted on the passengers side fenderwell. Follow the lines and you should see it. Did you confirm the black wire is grounded? Since your compressor did shell out I hope you did change the orifice tube since it catches the trash from the old blown compressor. If you do jumper the switch and the compressor does engage dont run it for long or it may ruin it. Once you get the compressor operating where you are at in Texas with our heat your pressures should be low side up around 50 and the high side should be around 250

 

That's correct. Without a charge in the system the low press switch prevents the compressor from starting. Not sure on an 82, on my 75 the switch is located midway on the passenger fender just under the lip near my puke bottle. Just jumper it and the compressor will start.

 

Posted this in another thread...
on the right/center of pic

 

Yeah that is the exact pic I was talking about. I thought that was what you were referring to.

Thanks KapsSA

 

Next time just pour the oil into the open pressure hose before connecting it. Dont suck and then charge with oil.
Before you try to run the compressor, turn it by hand at least 10 revs, so you don't slug it, especially since you loaded it into the suction side.

With a static 110#, that should be more than enough for the compressor to kick on. Did you get any 134 into the system at all? Or was this with just the oil?

If you jumper the switches, just watch the gauges so you see no more than 300 on the high side.
You can also just use a separate 12v jumper wire.
You might have to re-evacuate the system. If you do, suck the pressure side.

How did you switch from oil to 134 when charging?

 

So tonight I replaced the orifice tube and did find that there were some junk in it. So I re-evac'd both sides of the system. Jumped the low press. switch on and off not to allow it to run too long. But still getting 110# on the low side and 65# on the high side. The high side does go up when the clutch is running, but the low side stays stag. @ 110#

I don't think I got any freon in the system, if it did it was very little.

The problem is that I cannot get the low side to suck any freon. Is it possible that the accumulator is also clogged? If so I think that the best approach method is through the fender well. Anyone else have any angles of attack.

Any other ideas? Previously the AC worked great, great for a 'Vette anyway. Air temp from the vents would get down to 45. So my theory is that I have a clog somewhere on the low side.

 

Why did you replace the compressor?

 

MY compressor took a crap, locked up on me. I replaced the orifice tube last night. Going to replace the accumulator tonight. Have you replaced the accumulator? It does not look like a friendly repair. Have to pull off the wheel and inner fender well?

 

Pull the "gills" from behind the front wheel.
cut the pipes to get the old one out. the new one will be easier to install.

sounds to me that your compressor died, not just the clutch. If you have metal in your system then you must flush or replace the ac condenssor at the front of the engine.

Check the large rubber hose that lays across the upper control arm on the passenger side. usually the control arm rubs a hole in the hose and you loose your freon.

 

IMO - Changing the compressor without replacing the drier and orfice tube is like changing your engine oil and not replacing the oil filter.

30 years of worn metal and aluminum shavings, rust, dessicant are all plugged up in the drier.

Changing it will be easier if you can get it on a lift so you can get to the nut on the lower fitting from underneath.

Not a fun job, but doable with less than a six pack

bigredbrad

 

You will also void any warranty if you cannot prove you replaced those and flushed every piece in the system. Almost all require the proper PAG oil too.

 

On a '77 you can remove the accumulator by first removing the coolant tank. Then you can lift the accumulator up to get a wrench on both hoses. The hoses are the only thing holding the accumulator in place. There should be a thermostat located just to the left of the accumulator, on a bracket. Two wires coming off of it. One goes to the low pressure switch on the passenger fire wall. The other goes to the compressor. There should be a third wire, your power source, coming out of the firewall. That wire also goes to the low pressure switch. If they're not hooked up correctly, it'll never cycle. Ask me how I know. When you replace those parts, you really need to replace the compressor, accumulator, and orifice tube all at once. You also want to put about half a bottle of compressor oil in the compressor and hand turn it 8-10 times before installing it.

 

Like the others have said you should replace the accumulator to maintain your warranty. I dont believe the new accumulator is going to cure your problem. The orifice tube is designed to catch the trash when your compressor shelled out. I think you have an electrical problem. Even if your system is totally clogged if your pressure is up to 110 that should engage clutch on the compressor. You said that you jumpered the low pressor switch or did you jumper straight to the compressor? When the compressor engaged what were your pressures? When you had the compressor jumpered did you try adding freon?

 

sounds like you're using an a/c machine, if that is so after a compressor problem metal filings can likley get into the system from the compressor having ceased up causing an orifice tube to clog and the reciever dryer, it is recomended to replace the reciever dryer when preforming a retofit from R-12 to 134. remember just cause you could pull a vacum if on or the other is clogged it doesnt nesecarly mean you draw down the entire sysrem before or after the restriction, if you are using cans to refil you will need the compreor to run, especialy after using your existing vacume on the oil charge.

 

After replacing the accumulator and orifice tube and pumped down I was able to get the car to take 2 cans of 134A with low side pressure approx 30#s. This is with bypassing the low pressure switch. Connected the switch again and tried to charge the 3rd can but the pressure skyrocketed back to 120# and would not take any more freon. Just like before. The high side pressure remained constant at approx 250# The compressor began to squeal and act like it wanted to seize up. So i shut down and called it a night.

On Max AC I noticed with the low pressure switch back on the clutch does not cycle and it stayed on constantly. I think that the clutch should cycle on and off. Isn't that correct?

So my questions are:

1). How much oil should be put in the compressor, system? Did I not charge enough oil?
2). How many cans of freon should a full charge take?
3). What should low and high side pressure be?
4). Should the compressor cycle?

I also flushed out the condenser, and evaporator so I know that I dont have any blockage.

It is getting about the time where I throw hands up in the air and take in to a shop. I hate to do that, but I am not sure what I am missing here.