Advance AC help needed

[umina]

Hi, my 2000 GP GT has AC issues. When i bought the car, i put a can of r134a in, and the passenger side got cold while the drivers side did not. Both sides get warm when dialed in and both sides will put out vent air. I have no diagnostic error codes in the CJ2 ACC unit. I have the professional AC Manifold gauges and the system runs constant 25lbs (on the low pressure side) when the compressor is engaged. With the system off i get around 100psi on high and low sides so the pressure equalizes and holds.

Tonight i put a can of R134a with UV leak detect dye in to see if the shaft seal was bad or something else. I can't even get the AC to get cold anymore, the low pressure side pipe at the firewall won't get cold unless i'm adding refridgerant (even though it sits at 25lbs like it should). Drove the car round and round and used the UV light, no leaks under the hood. I'm pulling my hair out with this, any suggestions? could i have a bad pressure switch? This constant pressure AC pump is hard to diagnose since it is always running (no cycle on cycle off). I need help, don't want to take it to the garage as i've never had to have someone else work on my cars but its gonna be 90 here this weekend and i need cool!!!!

and strangely, the low pressure side pipe got cold tonight for a minute and the passenger side started to get cold (after letting some pressure out from the low side with the car turned off but i could not duplicate again), then back to nothing, pipe went back to normal temp. Sorry for the long post, just don't want to forget anything and save us all troubleshooting time.

[BNaylor]

What reading are you getting on the high side when the compressor is engaged?

[brcidd]

Number one failure mode for a V-5 compressor is a shaft seal leak- so it would be best to look there first- is there oil slinging out onto the nearby components? like a radiator hose etc---also common are compressor o-ring leaks- is the body of the compressor oily--- it would be best to start over- so you know where you are at- which means- recover any remaining refrigerant, evacuate the system, and add back the proper charge amount- but you may not have all the tools to do this.....perhaps you know someone who does....

[BNaylor]

Originally Posted by brcidd

Number one failure mode for a V-5 compressor is a shaft seal leak- so it would be best to look there first- is there oil slinging out onto the nearby components? like a radiator hose etc---also common are compressor o-ring leaks- is the body of the compressor oily.

That is not necessarily true. The Delco/Harrison V5 variable displacement compressor is very reliable and there are other failures at the top of the list that I know of. Some minor oil seepage out the seal over a period of time could be normal and is not a sole indicator the compressor shaft seal is in fact bad or the system has a gross leak. Also, it is common to have residue oil from a leaking front valve or front crank seal cover gasket coat the compressor. The determining factor is a gross loss of refrigerant and best way to test it is with leak detection dye and leak detection lamp. Also, 25 psi at the low side does not mean the system has a leak or way out of specs. He could have a restriction someplace possibly at the orifice/expansion valve or even a flaky compressor but a high side reading should confirm that and if the readings correspond to the A, B, C , D charts per the FSM.

The OP claims he has professional A/C manifold gauges and should post what his high side figure is before giving up. Hopefully he is using them properly.

[umina]

OK, my high side is indicating 125psi with AC on full blast, it was about 82 degrees here today when i ran this test. This pressure seems to low, shouldnt it be between 175 and 200 for this ambient temperature? I checked again with my UV light and there is no leakage anywhere i can see. with the car off and equalized, i'm still reading about a 5 pound pressure difference between high and low which is normal i think (about 100psi on each side). I also need to mention that the tiny tube that goes into the firewall directly beneath the low pressure side tube gets very cold with the AC on. I'll go out and measure again with car running since i just did some running around in it with the AC on just to try and circulate it.

Maybe this is a dumb question, but say the system is ridiculously over charged, wouldn't i get abnormally high pressure readings on the high side and low side? I say this because since i've owned the car i've put SIX 12 or 13oz cans into it and if its not leaking, where is it all going? Two of these cans had UV dye in them, and i see no leaks anywhere with my UV light and glasses......

UPDATE::
Just checked pressures now, 24-25psi on the low side, 150 on the high side, verdict? (and the little tube on the firewall is ice cold, this is not the one with the low side valve on it, its just below it, and the low side tube was cold when i first started the car then immediatly went room temperature.......)

[BNaylor]

The static reading with ignition to off appears to be good. The high side reading with A/C on is too low and based on the low and high readings together it looks like you have a low refrigerant charge. You should have a sight glass on the manifold pressure gauge. Any bubbles visible?

The other possibility would be blockage or restriction when the low and high readings are that low. Does the low reading fluctuate rapidly any? If so then the expansion tube/orifice may be blocked.

As to an over charge the readings don't support an over charge condition. That is a lot of R134a used considering the system only needs around 1.8 lbs or around 30 ounces. So good question as to where it is all going. If you have access to a vacuum pump you can pull vacuum on the system and during the process watch the gauges to see if there is a leak. However, you'll have to evacuate and recover what is currently in the system first and start from scratch.

[brcidd]

The little tube that is cold going into the firewall is after the orifice tube- which is under the brake module-- so it being cold is perfectly normal- it is on the low side so it is to be expected.....you are losing charge, if you have added that much refrigerant-

With everything quiet- lean down and turn the compressor clutch driver by hand slowly- listen for any hissing as you rotate it-- I have gently pushed and pulled on them to hear it before- or slip a business card in the air gap- between the driver and the pulley- see if it comes out oily and look at it with your black light and UV glasses see if you see dye evidence--also this works best in low light conditions- like after dark-- the dye will jump right out at you then......a no doubter

[umina]

The readings don't fluctuate, they seem pretty solid. Is it possible there is a puddle of refridgerant inside the dash somplate leaking out of the condenser? I figured cold was going in but none was coming out, though if i had a blockage or restriction, wouldn't my compressor sieze or make noise? I'm getting really tempted to try that patented AC leak sealer stuff (like $30), cause i can't throw $700 at getting this fixed, got a baby on the way and i only paid 2k for the car in the first place! I'll try that business card trick, and stupid question but you meant turn the AC compressor by hand with the engine off right? (Yikes, don't wanna lose a finger!)

[BNaylor]

You mean the evaporator? The condenser is the component that looks like a radiator located in front of the radiator. As to blockage or restriction like at the orifice maybe not initially but sooner or later yes because the compressor will be starved for oil. Also, the same if you have been running low on refrigerant for any length of time.

As to using stop leak regardless of whatever brand or claims that is your decision based on your budget but I'd recommend not using it. May cause blockage in the condenser, accumulator, service ports and may affect the variable control valve operation in the V5 compressor.

It may not tell you where the leak is but the best way to confirm if you in fact have a leak someplace is to pull vacuum with a vacuum pump. You run a deep vacuum on the system at around 29 in for approximately 30 minutes. Then take a break for 30 minutes after turning off pump and see if the vacuum on the low side gauge dropped indicated the system is not holding vacuum and thus a leak. You can rent 1.5 CFM electric vacuum pumps at places like Autozone.

[umina]

Now before i can draw a vacuum, the system must be completely evacuated right? Maybe i'm using my guage set wrong, but the little bubble sight glass on it doesn't have anything in it unless i turn the red thumb wheel on the gauage (as opposed to the on on the high side fitting) to the open position. Should I have the blue and red knobs on the body of the gauge turned to the on position to use the sight glass? Then when i turn the car off, the gauge hoses are full of refridgerant and pressure and i have to bleed them off slowly by unscrewing the yellow charge/vacuum hose from the T fitting on the gauge body with a rag. I'm gonna call around today and get an estimate of what it will cost to evacuate/recover whats in the system and do a leak down pressure test like you reccomend. What should i expect to pay for this service roughly?

[BNaylor]

Actually you just need to recover the refrigerant since it should not be dumped into the atmosphere before pulling vacuum. Also, technically the vacuum process is part of the evacuation process since it also pulls out any moisture and foreign gases like air out out of the system. The oil normally stays intact in the compressor, condenser, evaporator and mainly the accumulator during a DIY evacuation.

What brand a/c manifold gauge set do you have? Can you post a pic. Of course blue is low side and red is high side. Also, do you have the manual turn off/on valve at the connectors for the low and high service ports? If my memory serves me correctly you should get something in the sight glass with just the low side blue valve open or when adding refrigerant. High should be closed. During the process the yellow hose should be securely fastened to the T fitting or closed off of you will lose the charge or unless you have it connected to a can of R134a with the valve closed. BTW - Just for reference the yellow hose is where the vacuum pump is connected. That is normal for the manifold hoses to have a residual charge after being disconnected and they way you are bleeding them off is fine.

As to cost it varies. Some shops charge a diagnosis fee before doing any work. Some shops won't touch it unless they do all the work since they have to guarantee their labor. Bottom line is professional A/C work can get expensive. Some local shops in my area will do a free recovery of the refrigerant since it is recycled. Then all you have to do is pull vacuum and then recharge DIY from scratch. Best thing to do is call around, explain your situation, see if they will do want you want done and have them give you an estimate. The GM dealers probably have the best relevant A/C service equipment like the ACR 2000 service center but will probably be expensive. Good luck!

[umina]

My gauge is is made by US General, as seen here:

http://www.harborfreight.com/cpi/cta...emnumber=92649

maybe since nothing comes into the site glass all i'm measuring is air at the low side service port? I double checked last night after running the system for an hour of driving and no leaks with the UV dye. Gauges now seem to be reading 21psi on the low side and a bit below 150 on the high side with car running and AC on full. Definitely losing charge someplace and since i don't see any leaks under the car or in the engine compartment, it must be at the evaperator inside the dash (which is of course probably the most expensive repair since there is soo much labor involved). I may be at the mercy of a shop for this one but probably just go without AC this summer (argh! Have to drive the miniVAN!! :o) can't afford a spendy repair.

[greenlight99]

Ok, so I had this exact same problem when I first got my 99 Grand Prix. This was a common problem for the GPs from 97-00. This sounds stupid but the reason for it was because GM put the wrong sticker on some of the vehicles during these years. My guess is that your sticker says that you are to put 1.88 lbs in the system; however, it is really suppose to have 2.25 lbs. In fact, the correct sticker part number is: 10442041. I did this and have had cold AC on both sides ever since. I couldnt believe it when I found this out but it solved the problem. I guess some came with the right amount of refrigerant from the factory and some did not. Good luck,

Brian

[BNaylor]

Originally Posted by greenlight99

Ok, so I had this exact same problem when I first got my 99 Grand Prix. This was a common problem for the GPs from 97-00. This sounds stupid but the reason for it was because GM put the wrong sticker on some of the vehicles during these years. My guess is that your sticker says that you are to put 1.88 lbs in the system; however, it is really suppose to have 2.25 lbs. In fact, the correct sticker part number is: 10442041. I did this and have had cold AC on both sides ever since. I couldnt believe it when I found this out but it solved the problem. I guess some came with the right amount of refrigerant from the factory and some did not. Good luck,

Brian

You think? I seriously doubt the OP's issue is a difference of 1.88 lbs versus 2.25 lbs on refrigerant charge which is the first time I've heard about it. He has other issues which is not just a very low charge if you carefully read the post history. IMO it depends on where your GP was delivered. 1.88 is correct from what I can see. When I serviced my '97 GTP over 3 years I put in 1.88 lbs with the ACR 2000 servicer. IMO 2.25 lbs is too much for the region I'm located in based on low and high side readings. Also, just recently did the wife's '99 Regal LS after finding a bad variable control valve in the compressor. Charged to 1.88 lbs R134a. Vent outlet temperatures are well below 40 degrees F both driver and passenger side in normal A/C mode with blower in low speed. Any references or TSB's on the issue?

[greenlight99]

I'm not going to say that this is THE answer but on my 99 gtp with dual zone, I had cold air out of the passenger's side and none out of the driver's side. I found this http://www.clubgp.com/newforum/tm.as...059089#3213872
and decided to try it. I work at a shop and we have a professional AC machine so I was able to get a more precise reading on the amount of refrigerant I put in. Sure enough, my AC worked great after this! Both sides were blowing cold air. As to Tsb's, Check this out:
http://www.autoacforum.com/messagevi...threadid=10601