Help me figure out A/C problem?

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.

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.

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?

Thats what I did.

Where is our AC guy what knows stuff?

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.

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

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

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.

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.

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.

can u force the compressor on by jumping the relay?

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.

Whats ur coolant pressure when the compressor is engaged?

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.

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

Well i was leaving flagler beach and was all happy my a/c was working when i heard something under the hood like i ran over a wire in the road or something. so i pull over and smoke is coming from under the hood. The sound i heard was the belt shreading cause my compressor locked up and the seal blew leaking coolant all over the front of the engine. I heard the last of the coolant leaking out. So i had to call my pops to rescue me and get it towed while i hopped in my backup car (srt4) and just barely made my court time to get divorced. So this week i'll be replacing the compressor the dryer and the expansion valve. I'm just glad my condenser didn't go but i might replace that too. Hey at least i'm single now and don't have to hear the bitching about dropping money into my car.

Yup, that is a very bad day.
However, the divorce kinda made it balance out if it was anything like mine. The day I put my first wife on an airplane back to her mother was one of the monumental turning points in my life -- looking back, 25 years ago, it was better than any birthday and I dropped my wedding ring into the garbage can at the airport exit --- there was this kinda walk-by, no effort or ceremony aspect to dropping the ring into the convenient trash receptable without interrupting my stride to the parking lot -- a way cool moment.
I have found a guy on ebay...
do an ebay search under this dude's sellers name: "discountape"
He sent a quick reply to a question I had -- has a decent feedback too.
A compressor, accumulator, orifice tube, condensor, a qt of purging solvent. system oil, and o-rings total to under $350. Understand that your system is slightly different than mine.
I went and saw my mechanic yesterday who seems to have a different memory about how he insisted that I change my condensor when he replaced my my compressor two years ago -- also tells me that I should have installed an auxillary filter. Dang, I remember things differently. But I certainly am clear about being charged over $600 for a new compressor.
The word is that when your compressor blows its cookies, the debris contaminates the condensor. I'm not sure anymore of the order of components but you gotta be sure that the system is free of debris.
Good luck on your new life. I ended up married to a great girl some years later. Does your ex have a good lookin' sister?

Where is our AC guru?
... gotta understand that we could use some real advice here. I've been reading a lot about AC but a little knowledge is dangerous...

Doesn't most of the 134a juice u put in have the proper oil in it? It's 384 bucks plus shipping for my compressor, expansion valve, dryer, and condenser. I think i'm gonna put it all in myself and then take it somewhere to do a proper first time charge. I gotta get in my book and see if it says anything about that.

more to read http://www.ackits.com/c/BlackDeath/Auto+AC+Compressor+Failure+(Black+Death).html

The link is an excellent read. My orifice tube looked worse than the one on the link page. I'd try to purge some of my components but here is the problem. I used both acetone and lacquer thinner to clean out a single straight line. Initially, the solvent came out quite dirty. When is was runing through clean, I stuck a length of nylon weedwacker line through it and it pushed out a whole bunch of gunk that does not disolve via acetone and acetone is really hot stuff.

not as bad as i thought. Crawled under there today and noticed the refrigerant hose assembly rubbed on the compressor pulley, cut through it, sprayed the frig oil on my pulleys, jumped the belt, the compressor clutch caught the belt and ate it to pieces. Got the compressor out and it spins freely and clutch moves too. Ordered new hose assembly and belt. I know i have to put oil back in the compressor but how much and where do i put it? If i can figure that out i'll put it together and take it somewhere to get it evaporated and charged.

I believe that despite having a mess under your hood, you've actually had a change in your luck. A compressor failure is just the end and I would have assumed that is what happened also. Replace the lines, take it to a reputable service tech for an evacuation, new oil, and recharge and you should be a cool and happy again.

I'm knocking out a few of these bit and piece jobs I have laying around to get some extra cash and am going ahead with replacing everything. I just can't stand it when something is broken on my SS. Its kinda odd that when "my" car breaks there is an attitude that its a money pit. I make it a practice to use other sources of income to keep up with the maintenance. Generally speaking, the car hasn't been bad for repair costs. I can get 22 MPG if I keep my foot light and I think that's really great -- but I tend to enjoy on ramps to the interstate. That's good news about your AC.

I was looking at compressor oil and i'm not sure which one would be better. They have the oil u pour into the compressor it's self then they have the same oil in a charge can that you hook to the low pressure side and push it in that way. Both come in 4 fluid ounce cans. I'm thinking hooking it up and charging the oil into the low pressure side would be much less messy and i absolutely don't wanna drive it to a shop if the compressor is bone dry.

Your specific car will have a specific spec for the quanity of oil. The spec is intended for systems that have absolutely no oil in them. Due to the cost of parts and the fact the neither one of knows what we're doing -- a little knowledge is dangerous -- I'd either find a local AC guy who is willing to give you coaching or install the parts and take it to a pro for a full service. Too much oil will displace available refrigerent and too little or the wrong kind will generate more bad days.

I wondering, if the clutch isnt engaged, can i drive my car without any damage to the compressor since it doesn't have and refrigerant oil in it. I'm thinking it's ok cause only the pulley is spinning and not the compressor internals?