The Cooling fans are working. I replaced ac/fan relay, Check freon level all is good. I jumped the compressor it worked for about 5 minutes when I jumped it (put power to it). Then it stopped. It appears it not getting power or power is shutting off to the compressor. Any advice.
Note: The ac did blow cold when the compressor was running for 5 minutes.

 

How do you know the freon level is good? Sounds like it may very well be a high or low pressure shutdown- You can check switch voltages to diagnose. of course, a blocked expansion valve can also cause either pressure to be wrong .

 

While the compressor was running via a by pass it was guaged last night and the pressures were good. My AC mechanic friend did not believe it was an expansion valve. How can I test the switches? Are talking about the swich to turn the ac on or I would guess to check all of them. I will also look closer to the expansion valve. I am learning something new everyday about this car. I appreciate your advice and keep you posted. Thank you!

 

The high/low pressure sensor reports to the ECM which controls the compressor clutch. While not a chronic problem, failure at this point have been discussed on several occasions. The sensor is located in the high pressure line at the bottom center of the radiator. It should be replaced by an AC shop in order to evacuate the R134a and recharge.

 

Thank you for you advice I am trying everything to get the ac fixed.

 

I checked the high pressure switch on the line and the switch was bad. I just ordered one. I had the ac wiring schematics was able to check the switch by jumping it. I appreciate your advice it worked. Thanks for your assistance!
Tim

 

Well, the switch might very well be bad, BUT the fact that it runs and then shuts off indicates it MIGHT be a freon charge ptoblem. After running, the freon pressures might be normalizing to high or low values, then doing a shutdown. watch the gauges as it starts, then as it shuts off for small variations in pressure.

 

My neighbor is an ac mechanic he guaged it again today to check pressures. He said it was all good then checked the switch and the switch was bad. The compressor wasn't kicking on and off like it would be low on freon. After we checked it. I tapped on the ac switch and the compressor kicked on.

 

See how easy all this is . . . if a tap didn't work . . . get a bigger hammer.

 

Its true a hammer sometimes can fix things. LOL! I am learning.

 

Mallet ? lol Well, when hammering things down please be careful otherwise you could break something

 

I received my high pressure swith today and replaced it. Everything is working fine now on the ac. Thanks for all the advice and assistance! Mallets and Hammers do work!

 

Thanks for the update ,I am glad it works fine

 

Good to hear that you got it sorted, just be careful that you don't get confused and get a mullet instead of a mallet!

 

How does one trouble shoot this switch?

Also, does on have to empty the system, evacuate and recharge to replace this switch? If I remember correctly, that would be the case. Right?

So I'd like to trouble shoot before I bleed down and recharge.... only to find my compressor really is the problem!

Thanks for any input you can add. Greg

 

You do not say whether you have done a pressure test on the system but that is the place to start. The pressure switch is expecting to see greater than 12 BAR (175psi) on the pressure side of the system.

And yes, you will have to evacuate the system to replace the switch.

Here is the schematic of the switch. If you have correct system pressure then jumping the 20 bar wiring should operate the compressor clutch.

 

I new to the forum, my 4.0 stype is doing the same thing..I can't for my life figure it out
I bought the pressure switch, vacuum down and tried to charge up with one can to see if it engages with no luck. the relay is good, I trace the wire from the relay to compressor and getting continuity, it runs on when I jump it..how many psi should be in the system before the pressure switch triggles

 

Without looking it up seems I remember 22 psi. One can may not reach that level.

 

ok, thanks, but I stopped when the low pressure gauge went up to about 60psi while high side was around 90psi..which to me tells me the compressor is bad.
What do you think?
Leon

 

With the engine running, compressor clutch engaged if all you can get is 90 psi on the high side I would agree that there is a compressor problem.