2002 Pontiac Ram Air Trans Am ac is not cooling properly

[dannyual320]

Right or wrong, I used Nylog on the seals because I successfully used it on green o-rings many years ago. Most of the connections connected securely and I felt confident. However, two of them did not leave me feeling confident. The accumulator to suction hose connection and condenser outlet to liquid line connection.

I pulled a vacuum for just over an hour and then shut off the pump to see if the system would hold. Over the course of about 1 1/2 hrs it appeared to hold the vacuum . I decided to let the vacuum pump run a couple more hours for a total of 3. At the moment, the pump is turned off, pump valve closed and both gauge valves are closed. Both hoses are connected to the high and low ports. I'm going to let the system sit overnight and make sure it holds the vacuum before I proceed to charge the system with refrigerant.

I did notice that my vacuum pump oil got quite cloudy looking. I'll need to change that oil for sure.

https://www.amazon.com/photos/shared/Bs ... uqbVCeSlcN

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[dannyual320]

Make sure the AC system is fully charged with the specified amount of PAG oil.

I don't know what the specified amount of oil is for my system. There is no specified amount of oil listed on the sticker under the hood that tells me how much refrigerant my system takes which is 1 1/2lbs.

My Delphi compressor instructions had good information about how much oil should be added to each of the different system components. I went with what the instructions said because it was the only information that I had.

[dannyual320]

The good news is that the system held vacuum for 24hrs.


Now for all the bad:

I then put my refrigerant bottle on the scale and wrote down the weight. I then opened the low side valve and let the refrigerant in. Not much went in. Not anywhere close to a full charge. In fact, not even a 1/2lb. So I started the engine and tried to draw the refrigerant in. It was a real fight to get any in. My scale would slooooooowly count down 1/100th of a pound every 20=30 seconds. I tried reving up the engine to no avail. After maybe 30 mins of running the engine, I had about 3/4lb in.

At this point I said, "what the heck?" I turned the bottle upside down to see if I could add liquid refrigerant in. This worked. I got about .1lb to go in in a matter of 5 seconds or so. I did it again and again, putting the bottle back on the scale so I could monitor how much refrigerant was going in. I finally got just shy of 1 1/2lbs (1.43lbs to be exact) in and called it good.

I have to say that it's pretty cold here north or Houston, TX. Ambient temps this evening while doing the charging were about 40F but I was in my garage with the temp about 55F. I did raise the garage door because of running the engine and the garage was getting colder.

My H and L pressures didn't really make sense. H of about 65-70 and L of 38. Vent temp was 48F. I don't know if the low ambient temp has anything to do with it but it just doesn't seem to be right. I was hoping for vent temps of 40F or lower. I've spent a lot of money and a lot of time on this trying to do it right. I'm not happy with it at all right now.

[dannyual320]

Thank you Al9 for your consoling words describing what is going on.

I was wondering if that variable displacement compressor was "destroking" since I never saw a high side pressure above 70 last night.

About a week ago, I told my father-in-law that . in the past, I've noticed that auto ac systems act differently in the cool weather vs the heat of the summer. I told him that I was a little apprehensive about doing this final reassembly, charging and testing while we're experiencing abnormally cold temperatures for the Houston area. On the other hand, I just wanted to get it done.

For now, I'm just going to give it a rest and like you, wait for warmer weather to do a proper test.

[dannyual320]

Hello everybody. We've had a cool winter/early spring here in the north Houston area. Remember the great Texas freeze in February?

I drove the Trans Am for a quick drive to the gym and back on Saturday, 27 March 21 and it was in the upper 70s and muggy so I said that this would be a decent time to try the ac system. It had been a long time since I'd turned the ac system on. It's a short drive back from the gym (4 1/2 miles) but I did see 45F on my thermometer with the ac on MAX. I'd rather have seen 40F but I was satisfied with the 45F.

Back in December 2020 when I was charging the system in the cold ambient conditions, I was just a little shy of 24 oz of refrigerant because I just couldn't get it in. As the weather warms up over the next month or two, I'll continue to monitor my ac's performance and if need be, I'll add another ounce or or so to bring me up to 24oz total.

[dannyual320]

See? Vent temp climbed down as heat load (humidity is also additional heat load) increased.

I'd have turned AC on for a few mins during any warm spell. If I'm being 100% honest, I'll have to admit that there was a fear factor that kept me from doing this. I was afraid that the ac system wouldn't work or that the refrigerant had leaked out since December

Rather than adding one ounce or so, i'd recommend you visit an RRR equipped pro and have everything recovered, weighed and restored to proper spec. Dead on charge weight is critical with this system, since, as you've just seen, it uses discharge pressure to adjust vent temperature. This has been a long thread that has spanned months and many posts. I do own a Mastercool refrigerant recovery system as well as a very good air conditioning service scale.
That being said, I'm confident in my 1.43 lbs of refrigerant added in December. The only unknown would be if any of my seals weren't holding and the system is leaking some.

Other posters with V5/V7 comp equipped vehicles said, in archived posts that now got removed for some reason, that the real icy blast will come around 100F ambient. This I understand but I think that it goes against "logical thinking." I would guess that most people would assume that an ac system would produce colder vent temperatures if the ambient temperature were cooler. I'm confident that my vent temperatures will be even better than 45 when the hotter summer temperatures arrive here before the end of May.

[dannyual320]

It's been a long time since I've come into this thread. With the very hot summer here in the north Houston area, I've had plenty of time to experience how well my Trans Am's AC system is operating.

Ambient temps lately have been in the 95F area with high humidity. The lowest vent temps that I see are 45F. I'd like to see 40F but no matter what, the vent temp will not go below 45F. Well, to be honest, I've seen 44F with the blower speed on medium. The vent air is quite cold but with the car being black and a black interior, if I let the car sit in the sun, it takes a long time to cool the interior down when the lowest temperature that my system can achieve is 45F. Like I said, my DIY vent temperature benchmark is 40F.

During the system replacement last December 2020, there was one item that stuck out to me. I purchased a new "AC Delco" condenser. It was made in Korea as is the brand new compressor. I did notice that the new condenser was considerably thinner and lighter weight than the original condenser that the factory installed in the car. It fit perfectly but physically, it was thinner and very light. Maybe this has something to do with my vent temp ?

I know I'm comparing apples to oranges but my daughter's 2014 Toyota Camry has vent temps in the mid 30s ! I've seen 37F using the same thermometer. Her car is a medium dark charcoal color and with those low vent temperatures, the cabin cools down very quickly.

Anyway, I've got working AC in my Trans Am so overall I'm satisfied.

[tbirdtbird]

If you have 45, in many cases that is as good as it gets, and you should be pleased. Few get to 40.
Your daughter's car is a heartbeat away from freezing the evap core to a block of ice, especially with high humidity,, you do not want to be in the 30's.

As far as the thinness of the new condenser, welcome to bean counter 101.

As far as black car with black interior left in the Houston summer sun, you have triple trouble. There is another thread on here right now about leaving AZ cars in the sun and thence how difficult it is to get the cabin cool again. It is called heat soak

[dannyual320]

tbird, I'm quite happy with my AC. It works and it's keeping me cool in these stifling Houston temperatures.

I may have to keep an eye on my daughter's Camry. She got it from her grandmother in the middle of the past winter and it hasn't been on any long drives since we've had hot weather.

I still can't believe how light weight and thin that AC Delco condenser is that's now on my car. It seemed to have about half the mass of the OEM condenser.

[dannyual320]

As long as it's AC Delco and not some obscure Chinese stuff, i think you're good. Thinner wall means better heat exchange actually (as long as it's not plugged with junk or badly assembled).

You could try experimenting with a yellow or green control valve if you still wanted colder air. I've put a purple control valve in my compressor (should be the same color rating as yours) and 45F vent is the best i'm seeing too. Obviously recover any refrigerant from the system before removing the old control valve, though.

The condenser was a genuine AC Delco part that was made in Korea like the Delphi compressor.

Thank you for the control valve information and the confirmation about 45F with the purple. It occurred to me a little while back that maybe the control valve was limiting how cool the system would get but I wasn't sure. I'm pretty sure that I noticed a purple control valve on my Delphi compressor.

Can you tell me any more about the yellow and green control valves? ***IF*** I were to change the control valve, I'd put my Mastercool recovery machine back to work and recover all of the refrigerant in the system.