A/C Electrical Question

[ncc]

Hey all!

I just replaced the compressor, accumulator and orifice tube in my '97 EB 4.0 SOHC.

Everything went together fine, I had no problems at all. Until now....

The clutch will not engage on my new (remanufactured) compressor. I think this is an electrical problem although I am open to other possible causes.

With the engine running and the A/C Max engaged, I get 12.26V DC at the plug on top of the accumulator. But I get zilch at either of the two plugs on the compressor itself.

I have not as yet had the system professionally evacuated and recharged since it's Sunday and nobody's open. But I wanted to just verify that it would all work before I brought it in, so I precharged the compressor with PAG oil and did the same to the accumulator. Then I used an InterDynamics charging kit to put some refrigerant in the system. I hooked it up to the port at the accumulator and brought the gauge up to the "safe" zone. I let the system run for a bit after that to see if it would engage, but still no dice.

Thoughts????

Thanks a bunch!!!

Jeremy
'97 EB 4.0L SOHC

 

[budwich]

I assume the plug near the accumulator is your low pressure switch.... near where you were adding 134... right? Anyway, disconnect the connector from the switch and throw a short across the plug.... this allows the 12v that you are seeing to get across to your compressor (ie. in essence you are taking your pressure switch out of the circuit). Your compressor clutch should enable. Don't run in this mode very long if you have low charge or inadequate oil.

 

[shamaal]

As budwich points out, you may not have a problem. The pressure switch opens at <24.5 PSI and closes at >43.5 psi. As you have opened the system and there is no refrigerant, there is not enough pressure to close the switch and turn on the clutch. If you have a compelling need to watch the clutch engage, the switch may indeed be jumped in the manner described for a short amount of time. Remember without refrigerant there is no method of conveying through the system.

A FYI electrical schematic can be found at:
http://www.autozone.com/servlet/UiB..._us/0900823d/80/0b/a9/c7/0900823d800ba9c7.jsp

 

[Josh]

If your system is charged between like 35 and 50 psi, then it should run. I had a similar problem and it seems to be the a/c relay. I had 12 volts on one pin and the other is ground and it seemed the ground was not being made. I ran a jumper to ground and the problem was solved. No my compressor clutch slips after about 5 minutes of use or when the motor is reving. I think my 12 volt supply is week so I will run another jumper to solit 12 volt supply for testing.

 

[ncc]

Thanks for the replies, y'all!

I jumped the low-pressure switch and, sure enough, the clutch zipped right into action. Yeah!

I'll be taking it down to the shop this week to have it professionally evacuated and recharged, but of course all the stifling hot weather is now GONE!

Jeremy
'97 EB 4.0L SOHC