dalynchmob

Car is listed in sig. I have a brand new high pressure sensor for the a/c system since that was the problem last yr. The compressor won't come on unless i pull the relay and jump it,to force it on. The pressure with everything on is at 40,in the blue,on the gauge (where it's supposed to be) and it blows cold. So i swapped the relay with a different one of the same part number and the compressor still won't come on unless i jump it. I know its got cold juice in it, the compressor works, the high pressure switch is new, and the relays are good. Where else should i investigate? Is there another sensor or pressure switch i could replace? I'm sure i'm not the first this has happened to. Any advice would be much appreciated.

wrnchbndr

Yo dude, I'm feeling your pain also. Somebody chime in if I am wrong here. I have a 2000 SS that I'm trying to figure out the AC. My computer acquired a code for the low refrigerent pressure and I believe that I needed to reset the code before my compressor would kick on without jumping the relay. This is right where I was at just an hour ago. I jumped my relay, and then was able to pressure up the R134. I disconnected the battery negative terminal to reset the computer and now my compressor works as it is supposed to. The problem I have now is that I'm still getting no cold air despite purging the system fully at least once.

I suspect that I have a clogged expansion valve but I cannot find its location. Does any know where exactly the expansion tube is on a 2000 SS M6? I have all of the plastic and the air flow thingy removed from the top of the radiator and that was a waste of time...

My local mechanic hit me real hard for replacing the compressor two years ago charging me twice what I could get a replacement for at the local parts store so I'm determined to fix this myself. Its likely that debris from the previous compressor has clogged the valve.

Sorry about hijacking your post but hopefully we'll attract an AC go-to-guy.

dalynchmob

I'm not getting a code or SES light. I wasn't before either when i had to take it in and got charged 167.00 to find out it was the high pressure sensor. So this time think the same thing i replace the sensor but no luck. Maybe i should reset the computer? Thats the old disconnect the battery deal right?

wrnchbndr

Thats what I did.

Where is our AC guy what knows stuff?

wrnchbndr

I've looked for a block of sorts that is attached with torx or allen screws near te evaportator and come up with nothin. I have a digital picture of the right side of the engine bay and if I can figure out how to post of photo, I'll do that.

How you doing with that compressor? The fact that it turns on at all is a good thing. I was able to find a full series of wiring diagrams for my 2000SS and this is what I used to deterine the proper terminals to jumper the compressor. My compressor will not run at all without a jumper if the pressure is low and this is a function that is controlled by the PCM. As with yours, there is no SES light under a low refrigerent pressure condition but the fact remains that the pressure is monitored and I needed to disconnect the battery to reset the PCM. If you can find a wiring diagram for your year/model on the net it may give you a clue to proceed. It follows that there is a pressure switch giving information to the PCM and if this info is missing or incorrect you'll have the problem you have now. I'm still looking for my expansion valve or as others have called it an expansion block.

dalynchmob

The expansion valve or block is very obvious on the LTs not so much on the LSs i guess.

dalynchmob

Holy crap! Just reset the computer and it works perfect now. Now we need to figure out urs.

wrnchbndr

Its so cool to have one of those "holy Cr*p" moments.
I've been searching the posts using "air conditioning" as a search phrase and am just not finding any info. Its easy to get impatient when waiting for a reply but I'm confident that someone has the answer to my problem. I can't find my expansion valve. I've seen a picture of the "block" that is attached to the evaporator with an allen screw and this does not exist on my 2000 SS. I know that there must be a component that performs the same function -- It may be contained within one of the hoses or its within the dryer/receiver, or, its something really dumb and I'm missing a key point. I have the car taken apart and am drydocked. Please consider that I'm a grown guy needing to grovel to my 20 year-old deadbeat son for a ride to work. I need some help.

dalynchmob

i can't help but snicker a little about catching a ride from ur son sorry. Do u have a haynes book for ur car? I can't find anything saying yours even has an expansion valve. Someone has to know if the LSs had a different system. I only found an evap core for urs.

wrnchbndr

Well I found the "orifice tube". Its inserted into the lower line that comes out of the evaporator. This is the line that has the pressure sensor unit. The line connects to the condersor in front of the radiator. All of the theory that I had read about auto AC had led me to believe that the flow of refrigerent was coming from the aluminum can thingy but actually a few internet sites since have explained the "Orifice Tube System" which is different. My aluminum can thingy is called an accumulator. The orifice was seriously clogged with metal shavings and guck. I removed the entire line between the condensor and the evaporator and ran mineral spirits through it along with a length of weedwacker line. The entire length of tubing was filled with black guck that did not readily wash away with mineral spirits. My guess is that the entire system is compromised by this contamination and I'm prepared for needing to replace everything. The evaporator and the condensor my be able to be flushed but I'm going to need to find a cleaning agent that will break down this black guck. I suppose my compressor is shot unless someone has a suggestion about some product or process. I'm putting it all back together but don't have much hope.

dalynchmob

can u force the compressor on by jumping the relay?

wrnchbndr

yes. Jumpering engages the clutch and then resetting the PCM will make it run via the relay. I do not believe that it is cycling now that it is all put together. I ran it for about an hour today. The compressor clutch is still engaged but there is no cool air or feeling of a cool tube on the evaporator side of the orifice tube. I pulled the orifice tube again this evening and it is not clogged or even dirty. I believe that the compressor is just not functional internally. More tests tomorrow. I need a high-side pressure measurement.

dalynchmob

Whats ur coolant pressure when the compressor is engaged?

wrnchbndr

The pressure is at 35 with the compressor engaged, the AC set to Max, and the PCM behaving itself (no jumper needed). There is no fluctuation in the pressure reading at all regardless of engine RPM even turning on or off the AC. My compressor is shot. I'm going to shotgun the system and replace everything unless I can get some reassurance of the posibility of using some sort of solvent and purge method for cleaning the evaporator and the condensor. The lines I can clean. I've learned a lot about AC in the last week.

I have a little bit of experience with refrigeration from repairing cryogenic converters on military aircraft for many years. The principals are the same but we used helium for the refrigerent. The automotive system is much more simplistic but it sure would have helped to see a functional diagram of my particular`car.

wrnchbndr

I'm wondering if I said something offensive -- no replys from an AC guru...