'91 OCC A/C Issue, no cold but no error

Hello all, I've finally gotten around to having some spare time to work on my wagon and I think this is the first thing on the plate (being as I live in ABQ, I want to get this fixed before summer!)

My A/C doesn't blow cold anymore. Heater works fine (REALLY well, in fact) and the control unit is not showing any error codes. It is still the factory R12 system, so I went and found an R12 topoff kit to make sure it was good on pressure and the gauge put it right in the middle of the "Green zone" when connected to the low-pressure valve. I replaced the pressure cycling switch with a brand new one, and still nothing. Any ideas? I'm really hoping not to have to convert to R134a, I'd like to keep this one alive as long as possible.

More details. What does and does not work. compressor? clutch? ???

With the car on, and the a/c set to full high, does the a/c compressor come on? If not, get a rubber mallet and aim a swift tap to the front of the compressor, on the clutch....yes while the car is running. I know this is a redneck thing to do, but working in an a/c shop for 7 years here in Texas, many of my techs did this.

If not used for a while, an R4 compressor clutch can sometimes stick and not engage. If you tap it one time and it kicks the compressor on, it may then fix itself with some steady use, or it may be too weak to re-engage once it tries to cycle, in which case you should just go ahead and replace the compressor. In most cases trying to just replace the clutch on an R4 leads to a front seal leak.

Good luck!

-Mike

It does not appear that the compressor is coming on. I will try unsticking it and report back later this evening.

If it comes down to it, can the compressor be replaced without special tools or draining the system, or should I take it to a professional?

zombiegristle wrote:

It does not appear that the compressor is coming on. I will try unsticking it and report back later this evening.

If it comes down to it, can the compressor be replaced without special tools or draining the system, or should I take it to a professional?

You will have to evacuate and re-charge the system to replace the compressor, and makesure the system is flushed well before re-charging. If you have to do this, save up for a new one or look for a new one on Ebay (have seen real deals there on new R4's)...it'll last a lot longer than a rebuilt. You will also need to replace the accumulator and orifice tube, both are cheap.

Good luck!

-Mike

zombiegristle wrote:

It does not appear that the compressor is coming on. I will try unsticking it and report back later this evening.

If it comes down to it, can the compressor be replaced without special tools or draining the system, or should I take it to a professional?

Have you tryed using a jumper on the connector to the low pressure switch?Before you replace the compressor,try the jumper wire
trick first and does the temp readout flash on and off when engine is running and AC switched to the on position?

I was under the impression the jumper trick was to check for a faulty pressure cycling switch, which I already replaced? And no, the display does not show any flashing readouts or error codes.

Also, rapping the clutch plate with a mallet didn't do anything but relieve stress.

Try this please,disconnect the battery for 30 seconds with the ignition key off,hook battery cable
back up,turn the key to on,your digital climate control will begin a countdown from 30,just let it
cycle thru and it will agaain cycle from 30,do nothing until its done counting down the second time.Now start car and see what the AC does,this trick has worked for 4 or 5 wagons here and I
hope it works for you!

Tried that as well, before I replaced the pressure cycling switch. Got the countdowns, but no cold air. That was several weeks ago.I will try it again tomorrow morning, however.

Dam,that almost always works!

Don't forget that right after the countdowns finish you're supposed to put it to full heat for 1 min, then go down to full cold for 1 min. You should here the cutoff door close when going from hot to cold. That's how you calibrate the blend actuator, At least I think that was the procedure. Don't have my FSM handy but it was in there somewhere's.