2002 Pontiac Ram Air Trans Am ac is not cooling properly

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dannyual320
Posts: 30
Joined: Tue Aug 18, 2020 2:23 pm
Location: Montgomery, TX (just north of Houston)

2002 Pontiac Ram Air Trans Am ac is not cooling properly

Postby dannyual320 » Sun Aug 30, 2020 6:48 pm

Hello to everyone. I'm Danny and I was a member of this forum way back in the 2007 timeframe when I did an R12 to R134a conversion on my 1991 Mustang GT. I had to re-register (different user name this time) since the forum didn't remember me from back then. This forum was very helpful and I purchased the "starter kit" from Arizona Mobile Air. I did a successful conversion and I enjoyed icy cold 40 degree vent temps in that car all the way until I had to pull the car off the road due to saltwater air rust damage. I lived right by the beach in north Florida back then.

I ordered my Trans Am back in the summer of 2001 but it is a 2002 model so I'm the sole owner and I know all it's history. The ac has always blown cold but the variable displacement compressor would't "variable displace" and my evaporator would freeze up if I was on a drive longer than 1 hour with the ac on. Those longer drives don't happen too often so I've made due with the faulty compressor since maybe around 2012.

I'm now living in the Houston, TX area so summer heat is a real problem. I noticed early in the summer that the car's ac would take a while to start cooling down. Usually the cooling was immediate as it is in my wife's Honda CRV and my 2001 F250SD diesel.

I started driving with a thermometer in the vent so I could monitor the cooling. It wasn't cooling good; vent temps were 55F and sometimes they would dip below 50F. Usually 55 (or higher) and quite slow to cool down to that.

I've still got all of the tools that I bought from Arizona Mobile Air and I've used the gauges about 6 weeks ago to take some readings of my Trans Am's ac. I wrote all of the numbers down but I can't find them to post. I added about 4 or 5 ounces of R134a. I do have a real nice, accurate, ac scale but I just don't remember the exact amount I added. I got slightly better vent temperatures and over the course of the next 2-3 weeks the car would occasionally cool down to about 45F. It was still a little slow to cool but it was working better.

Unfortunately as time went by, the cooling took a big turn for the worse. Now my vent temps won't go below 75F and it's a real fight to get them down to that.

continued:
dannyual320
Posts: 30
Joined: Tue Aug 18, 2020 2:23 pm
Location: Montgomery, TX (just north of Houston)

Re: 2002 Pontiac Ram Air Trans Am ac is not cooling properly

Postby dannyual320 » Sun Aug 30, 2020 7:27 pm

I suspected that I had a refrigerant leak. One thing I noticed when I did the work 6 weeks ago was that there was fluorescent dye in the system. I don't ever remember installing any dye so I can only assume that GM installed it, right? Anyway, today I got real busy with my UV light looking for a leak. I looked everywhere. I even put the car up on jackstands to look for a leak from under the car. No sign of leakage anywhere. Years ago before I did my 1991 Mustang's conversion, I had a pesky leak that took me a long time to find. I ended up finding after looking from the bottom of the car. The condensation exit had plenty of fluorescent dye. I looked at the water exit on my Trans Am and there was no sign of fluorescent dye. At least I won't have to pull my dash!!!!

I hooked the gauges back up and took some readings. Ambient temperature was 93 degrees and the humidity was high. I had the car doors open, blower on high and ac on max.

engine at idle
L 34
H 205
vent 88F

engine at 1500rpm
H250
L30
vent 85F

I then shut the engine down and noticed the high and low pressure equalized almost immediately on both gauges. I'm thinking that says something about the V7 compressor.

I started the engine again and got:
idle
H245
L36
vent 85F

1500rpm
H fell to 210 as both radiator fans kicked on high
L25e
vent 85F

At this point I decided to add just a bit of R134a to see what would happen. I was slowly adding refrigerant while watching my scale. I only added .17lb or 2.72 oz. Gauge readings were:

idle
H295 and climbing (fans on)
L31
vent 79F

Since the high was climbing, I shut the engine down without getting a 1500rpm gauge reading. I waited a few minutes and restarted and took some more readings.

idle
H330
L26
vent 79F

1500rpm
H350-375 and rising. I let off the throttle because I was scared of too much pressure
L25
vent 78F

As you can read, high pressures were getting higher as time went by. The rise in the H side were rapid even with both radiator fans running on high speed. I was all by myself but if I had had a helper, I would've sprayed the condenser with a garden hose to see what would happen to the H pressure. Under the hood, the tube just past the orifice tube was cool but not super cold. There was no frost or even sweating. Nothing else felt cool.

I'm hoping that with all of this information that someone will be able to tell what the problem is. As long as the real culprit can be identified, I'm pretty sure that I can do the work to fix it. Thank you for reading all of this that I've posted!
dannyual320
Posts: 30
Joined: Tue Aug 18, 2020 2:23 pm
Location: Montgomery, TX (just north of Houston)

Re: 2002 Pontiac Ram Air Trans Am ac is not cooling properly

Postby dannyual320 » Sun Aug 30, 2020 7:32 pm

For what it's worth, my car's OEM, V7 compressor is a made in Korea Delphi unit.

https://www.amazon.com/photos/shared/I3YQk4KJTVuklB-Aoc5fxw.FEQQ_U06PBneDjjU-myRG9
Al9
Posts: 204
Joined: Tue Mar 10, 2020 3:26 am
Location: Southern Europe

Re: 2002 Pontiac Ram Air Trans Am ac is not cooling properly

Postby Al9 » Mon Aug 31, 2020 12:58 am

dannyual320 wrote:The ac has always blown cold but the variable displacement compressor would't "variable displace" and my evaporator would freeze up if I was on a drive longer than 1 hour with the ac on.

Prolly a dirty or wrong pressure rating control valve here. One color up could be a nice thing to try anyways, i found out with my CVC unit they eventually lose calibration and besides they're really cheap. What color is yours? For example if it's purple 41 psi, you could try replacing it with a blue 42 psi one. 40 psi yellow one? Try fitting a 41 psi purple one. And so on. Also, some V5/V7 control valves used to lack filters (a small plastic mesh filter located on the tip, that keeps the orifice responsible for compressor destroking from clogging up/jamming open) and create problems over time, and all replacement valves come with filters.

The proper way to service systems equipped with these compressors is recovering any leftover refrigerant, drawing a deep vacuum then charging by weight. All of this with the compressor not running. Never add refrigerant with cans. I think you're overcharged.

Leaks can be as simple as bad valve cores.

Suction pressures aren't indicative of control valve early destroking or abnormal compressor wear issues IMHO.

Can you block off water flow to the heater core, so to rule out any possible unintentional reheating issue?
dannyual320
Posts: 30
Joined: Tue Aug 18, 2020 2:23 pm
Location: Montgomery, TX (just north of Houston)

Re: 2002 Pontiac Ram Air Trans Am ac is not cooling properly

Postby dannyual320 » Mon Aug 31, 2020 7:20 am

Good morning, A19 and thank you for your reply.

Never add refrigerant with cans. I think you're overcharged.

Leaks can be as simple as bad valve cores.


Yes, I'm concerned that I'm overcharged as well. I just wonder why before I charged about 5 oz of R134a about 6 weeks ago that the system was taking a long time to start cooling and wouldn't cool below 55F.

I spent a lot of time under the hood and under the car using my test UV light looking for the dye as well as the telltale sign of oily residue. All was clean like new. Both valve cores were clean with only small signs of the dye there. I checked the condensation coming out of the outlet with the light and there was zero sign of the dye.

Can you block off water flow to the heater core, so to rule out any possible unintentional reheating issue?


Yesterday afternoon as I began my testing the engine was cool (well, 93F ambient!) as the car hadn't been driven for a couple of days. My vent temps were still very warm with the engine coolant cool. As I continued to run the tests and the engine came up to operating temperature, the vent temperatures didn't go up with hot coolant running through the heater core so I don't think that's a problem. However, I could disconnect those hoses just to be sure if you really think that I should.
Last edited by dannyual320 on Mon Aug 31, 2020 7:29 am, edited 2 times in total.
dannyual320
Posts: 30
Joined: Tue Aug 18, 2020 2:23 pm
Location: Montgomery, TX (just north of Houston)

Re: 2002 Pontiac Ram Air Trans Am ac is not cooling properly

Postby dannyual320 » Mon Aug 31, 2020 7:21 am

posted by me in post #2

I then shut the engine down and noticed the high and low pressure equalized almost immediately on both gauges. I'm thinking that says something about the V7 compressor.


I read this morning that this is normal with a variable displacement compressor, right?
Al9
Posts: 204
Joined: Tue Mar 10, 2020 3:26 am
Location: Southern Europe

Re: 2002 Pontiac Ram Air Trans Am ac is not cooling properly

Postby Al9 » Mon Aug 31, 2020 7:53 am

Don't really know about equalization times as a diagnosis for compressor health and i think that other members could help you better. But your expansion device is a fixed dimension orifice tube, not a TXV (which depending upon its control curve could possibly get its orifice narrower and narrower as the evaporator warms up, due to the increasing evaporator pressure acting upon the diaphragm to close the valve).

If no reheating is taking place, air could be bypassing the evaporator core fins.
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Tim
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Re: 2002 Pontiac Ram Air Trans Am ac is not cooling properly

Postby Tim » Mon Aug 31, 2020 9:21 am

Reclaim your refrigerant. Evacuate and recharge to spec. Otherwise, you will be guessing and addressing areas that there is no reason to address.
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dannyual320
Posts: 30
Joined: Tue Aug 18, 2020 2:23 pm
Location: Montgomery, TX (just north of Houston)

Re: 2002 Pontiac Ram Air Trans Am ac is not cooling properly

Postby dannyual320 » Mon Aug 31, 2020 3:10 pm

I don't own any recovery equipment. I watched a YouTube video of a DIY guy recovering his refrigerant. He says that he had about $600 in his Robinair RG3 + tank + extra hose, fitting etc.

What would be a ballpark price to have a pro shop reclaim my refrigerant? I guess I could call several shops tomorrow and ask.
dannyual320
Posts: 30
Joined: Tue Aug 18, 2020 2:23 pm
Location: Montgomery, TX (just north of Houston)

Re: 2002 Pontiac Ram Air Trans Am ac is not cooling properly

Postby dannyual320 » Wed Sep 02, 2020 2:12 pm

Yesterday I called three local automotive shops. Two didn't answer the phone and the third did answer. He talked to me about my diagnosis that I posted above. He then asked me if I had sprayed water on the condenser and I told him that I did not back on Sunday, 30 Aug 20. He told me to retest and spray the water on the condenser to see if my high pressures would come down.

I decided to spray the condenser with water and see what my high pressures would do. Today we had a rain shower which cooled things down so the ambient temp was lower at 87F and lots of humidity. Car was hot since I had been driving it. Upon starting the car I got:

Idle (both radiator fans on high)
H350
L25
vent 85F

I then sprayed some water on the condenser and the High started rapidly falling. The two fans went from high speed to low speed.

Idle
H175
L30
vent 86F

Continuous water spray resulted in the following:

Idle
H140
L30
vent 95

I shut it down and got my wife to help with 1500rpm readings. I never sprayed any more water but I suspect the condenser was still wet or moist helping it cool due to evaporation.

After restarting, the fans were on low and

Idle
H210
L25
vent 87F

1500rpm (I think the fans were still on low)
H155
L27
vent 93F

One more test after my wife cycled the ac switch to OFF then back to MAX resulted in:

Idle
H190
L26
vent 88F

The fans went from low to high speed when we did the 1500rpm test below:

H220
L23
vent 88F

At this point I called the shop back to let him know what I found. He said those numbers sound like I'm low on refrigerant. He also told me that he could recover my refrigerant but he couldn't tell me how much he recovered because his equipment was "old." I tried to question him about using an air conditioning scale (which I own) to weigh the tank before and after but he was adamant that he would not be able to tell me how much was recovered. I decided to leave it alone and thanked him for his help.

I then called a fourth shop to ask about recovering my refrigerant and telling me how much I have. They want $100 to do that.

I know that I need to know how much refrigerant is currently in the system. I just thought that I'd give an update on what I found and what I was told from the two shops that I talked with.

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