Automotive Air Conditioning Information Forum (Archives)

scusack71 on Tue May 24, 2011 4:05 PM

Year: 1996
Make: Pontiac
Model: Grand Am
Engine Size: 2.4L
Refrigerant Type: R134a
Ambient Temp: 70
Pressure Low: 0
Pressure High: 0
Country of Origin: United States

I acquired a 1996 Pontiac Grand Am with 67000 miles from my grandmother after she passed away. You can see it wasn't driven much but doesn't mean they don't break while sitting.

I tried out the A/C and no cold air, of course. I took the car for a spin to warm it up, connected my gauges, rolled all windows down, selected A/C High with blower on Max. Pressures are reading zero/zero and compressor clutch is not engaging... due to low pressure switch opening up, I assume?

Obviously, I have a leak and I'm not even sure when the last time it was ever used... maybe 1997 for all I know. I guess I'm looking for some advice of a starting point. I have several auto A/C tools I've acquired through the past, but only have the knowledge from operators manual and ACKits Forum to use them. I have gauges, 3 CFM Vacumaster pump, refrigerant recovery system (obviously won't need for this job and a digital filling scale.

I have read that maybe my type of compressor (not sure what model compressor I have) is infamous for leaking shaft seal... but I did try to look around the pulley and didn't see any oil residue... but maybe I can't see good enough since it's tight in there... and looks like a bear to access from the right wheel well.

I'm all ears if anyone has a rough outline of what I can do to successfully make this thing work.... assuming I don't have a fried compressor or any other catastrophe to worry about.

Thank you in advance.

Edited: Tue May 24, 2011 at 4:08 PM by scusack71

mk378 on Tue May 24, 2011 4:38 PM

See if it will hold vacuum. If the vacuum goes away quickly, there is a major hole in something, e.g. the lines or condenser.

GM Tech on Tue May 24, 2011 8:24 PM

Compressor shaft seal leak is number one, compressor belly o-rings are number two--

Go ahead and pull vacuum, if it holds, then charge it- you'll know how well it holds after that-- add some dye before pulling vacuum, then if it leaks out- than at least you'll be able to trace it. It may last 2 hours, 2 days, 2 months or two years---

-------------------------
The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......

bohica2xo on Tue May 24, 2011 9:13 PM

Another vote for evacuate & charge if it holds vacuum.

B.

-------------------------
"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

scusack71 on Wed May 25, 2011 7:16 AM

Thank you for the start... I'll keep you posted.

scusack71 on Sun May 29, 2011 5:56 PM

Well, yesterday I put a vacuum on it and held it at what appeared on the guage about 28.5 - 29" Hg for about 45-minutes. I removed the vacuum and let it sit for about 30-minutes and the vacuum held very good. I was about to go ahead and charge it up but the temp dropped like a rock since the rain was about to come.

Today, I ran another vauccum but followed the procedure by TRB, Evacuate and Charging Procedure.

I ran a vacuum for about 35-minutes and then shut off to let boil any moisture for about 15-minutes (no vacuum loss). Started vacuum again and ran for about 25-minutes and again cut vacuum off and let sit for another 10-minutes.

I set up my 30lb bottle and scale to my charging hose, opened the bottle and burped the air from the yellow charging hose at the manifold, reset the scale to zero.

Opened the low side valve and let it charge with engine off. It took about 4.5oz. I turned the ignition with blower on high, A/C to Max and monitored the refrigerant weight. While refrigerant was filling I noticed that the high side pressure stayed steady around 100psi and the low was around 35psi.

The placard on the car says 2.25lbs. It took about 10-15 minutes until I charged it to 2lbs 4.5oz and then shut off the low side valve and monitored the pressures. I monitored the pressure without the charging bottle and noticed the low side fluxuating between 25-31psi and the high side was steady at 95psi.

Here's my data for the end result:

Ambient Temp: 76-degF

At Idle: Low 25-31 oscilating every 2-seconds and High of 95 steady. Discharge vent temp was 82-degF

At 1500 RPM: the same 25-30 / 100 with a discharge vent temp also at 83-degF

Not sure what that means.... is something plugged up?

HVACNY on Sun May 29, 2011 8:49 PM

HVACNY on Sun May 29, 2011 8:53 PM

Are you sure it says 2.25lbs?With auto AC overcharging a system by a couple ounces is enough to cause it not to cool properly.Im not looking at the specs but that seems like alot of 134 to be putting in..

scusack71 on Sun May 29, 2011 9:43 PM

I took the service off the sticker on the crossmember under the hood:

NOTICE

Use only R134a refrigerant No. 12345922 or equivelant and compressor lubricant No. 12345923 or equivelant in this A/C system. Do not install R12 refrigerant or mineral oil lube. Damage to A/C compressor and system will result.

CHARGE WITH 1.02 KG (2.25 LBS) OF REFRIGERANT R134a

I watched the pressures as it was charging and both pressures seemed to behave the same throughout the charge as I annotated above. I don't have a clue unfortunately.

Edited: Sun May 29, 2011 at 9:44 PM by scusack71

GM Tech on Sun May 29, 2011 10:40 PM

Well with a variable pump and a variable expansion device, you can bet it is one or the other-- my money is on the TXV under the dash, it is probably stuck open- I'd be tapping on it or better yet, I'd overcharge it by a pound and see if it can decide to close up a little, 95 high side is not enough---low side flucuates just llike a low charge--So either drop your drain pan, and various other covers under dash, and whoppp on th eTXV, or over charge it and recover the extra after it decides to start working-- or you can just replace it and see if that helps....

-------------------------
The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......

scusack71 on Thu June 02, 2011 10:25 PM

Quote
Originally posted by: GM Tech
Well with a variable pump and a variable expansion device, you can bet it is one or the other-- my money is on the TXV under the dash, it is probably stuck open- I'd be tapping on it or better yet, I'd overcharge it by a pound and see if it can decide to close up a little, 95 high side is not enough---low side flucuates just llike a low charge--So either drop your drain pan, and various other covers under dash, and whoppp on th eTXV, or over charge it and recover the extra after it decides to start working-- or you can just replace it and see if that helps....

Well, tonight after finishing with what I could with my father-in-laws Jeep Grand Cherokee (another post), I went back to the Grand Am to tear into the lower dash to get to the TXV and tap on it as GM Tech told me. Well, the alternative may have been better since I tore that whole car inside out trying to get the box open to get to the TXV. I have a Haynes that shows no pictures after removing the center console and gives you pics for the car made 10-yrs prior, which has a totally different layout than my 96. So I just threw in the towel and put it all back together.

So GM Tech says to overcharge by 1lb. I'm willing to do it, but I just hope not to destroy anything or overpressurize... I am safe, correct??!! ). Now what is the theory by overfilling the system to make the TXV make an adjustment? I'm not familiar with TXV's but I looked at a picture of the TXV for this car and almost looks like a spigot valve... are these pretty robust in comparison to the TXV with the inlet and outlet in the engine compartment firewall? Just curious if I end up overcharging and I get no response... does this mean the TXV is bad and I have to tear that stupid dash apart again.... and try to figure out how the heck to get to it? Ok... done griping.... I thank you guys greatly for all your help.

scusack71 on Sat June 04, 2011 5:04 PM

UPDATE:

I tore the lower dash apart again to attempt to bang on that TXV again since I found someone from a Grand Am forum that did it with descriptive detail. So it went much smoother than last.

GM Tech suggested banging on the valve to see if it will start working since this seemed like the issue at the time. Well, I started the A/C system and whapped on the TXV several times in different locations of the valve (no worry... didn't damage any capillary's etc) and no success of cooler air.

So I took GM Tech's advice and tried to put another pound in it to see if that will make the TXV loosen up and close a little. When I connected my gauges up to it to service, they looked very different than what my charge was the other day with engine running. Before I had 25-30/100 after an awesome hours worth of tight vacuum. When I connected today, I turned the car on and A/C to high and my pressures were 25-30/50. So I didn't think much of it after that and started charging a pound into it with no problem... it took it very nicely. I let it sit and now my pressures were close to my original's from the 1st day, 25-30/98. However, the temp didn't cool.

So I was going to take next alternative that GM Tech gave and replace the TXV. So I started going up to Napa since they had one in stock and I forgot my wallet and went back home to get it. I thought about it and didn't understand how the pressures dropped the other day to today's values. So instead of getting the part, I started it up again and let it run and shut it off so I could try out my electronic sniffer in case there was a leak. I checked the evap box, all the fittings and around the compressor fittings and behind the pulley. No leaks. Then I started tearing the plastic covers around compressor since it's not an easy access compressor to just take a look under it to see if the shaft area under the V5 was leaking. The pulley shaft area wasn't leaking anything obvious, but the BELLY DEFINITELY HAD SOME OIL HANGING OFF THE BOTTOM OF HTE COMPRESSOR.

So, here's my question?? Do I need to rebuild this compressor, replace the reciever/drier and TXV (I rebuilt a Nippondenso last year for my 99 Intrepid 3.2L and it went good and I also saw a posting on how to rebuild a V5 on this site in the Tips and procedures section)? Of course is a flush necessary for this too? I have the HECAT Pulsator, but may have to purchase more juice for it. I'm trying to make this work nicely, but want to sell the car this summer. Just wondering if its worth the time and $$$. I'm guessing most would say it's not... but I have that problem of trying to sell anything in the best working condition possible so everyones happy and nobody necessarily tries to low ball negotiate with the A/C as an excuse. It seems to the one of the vital components everyone wants in a good running car or starts whining about it. i.e. drop the price and the heat won't feel as bad .

Edited: Sat June 04, 2011 at 5:13 PM by scusack71

mk378 on Sat June 04, 2011 6:21 PM

You definitely have a big leak. Apparently the belly reseal is not too complicated, GM Tech does them all the time. While the compressor is out and apart put a new control valve in it as it seems that that is likely the problem.

Even if everything else were working it leaked out in only a day, so it's not that practical to sell the car quick.