I live in north Houston and ac is an absolute must so I've been doing a lot of research and testing trying to determine what is wrong with my ac. I've got gauges so I can see what's going on with my high and low pressures. My high pressure eventually gets very high (400 psi) indicating insufficient airflow through the condenser. I sprayed the condenser with the garden hose and the H pressure came way down to less than 200. High pressure or low pressure didn't make a difference in vent temperatures.

Is there a way for me to "trick" the fans to come on high speed? During my testing with my ac gauges, it sounded like they were on high speed but I cannot be 100% certain that the driver's side fan was. I was able to get my hand behind the passenger side fan and I was confident that it was running at high speed. Not so certain on the driver's fan. If I have to, I'll take things apart to get to the fans so I can see them and get my hand in there to feel the air flow.

It was suggested to me on autoacforum.com that my 18 year old fans may be "tired." I'd like to confirm one way or another.

 

No A/C expert here but I would imagine if the fan were the only source of your issues that such issues would go away and the A\C would work fine while driving the car around. If you're driving on the highway or at a constant speed there would be enough airflow to cool the condenser provided you still have the air dam. I have a 2000 TA and can tell you that my fans don't really come with my A/C running at idle, that's on an 80-85*F day with 50-60%+ humidity (sounds like where you live it would be a bit hotter). The exception would be when the high side pressure gets in the the high 200s or maybe even over 300PSI but that doesn't happen often. My system is filled to nearly exactly what GM calls for.

Any indication of what your low side pressure is? Does it start to blow cold at any point when the high side pressure drops into the 200 range? Any idea of what your vent temperature is so you have an measurement of relative A/C performance?

When I had my system apart last year there was a descent amount of dirt, sand, and all kinds of debris in the tight space between the condenser and radiator. Much of it was stuck in the condenser and radiator fins and difficult to see until removing the condenser, as it mounts directly to the radiator. If you had excessive build up of crap there it might cause airflow issues with the condenser and cause pressures to shoot up but I would imagine it would take a lot to do that. Was the system ever messed with/added to? Any chance it was overcharged?

 

j498, thank you for your very informative reply. Lots of good, real world experience with air conditioning.

When the potentially "tired" fans were mentioned to me on the auto ac forum, I was thinking that my vent temperatures do not cool down at 55mph so that seems to be proof that the fans aren't the problem. I've told my wife that it appears to me that I may have two or three issues going on at the same time with my ac. Too many variables. A "moving target." Difficult to diagnose and repair when I haven't been able to identify the actual problem(s).

Hopefully before this coming weekend is over I'll have taken the time to take my Ram Air filter box and all the other stuff on top of the radiator apart so that I can get a good look of how things look in between the radiator and the condenser. The front of the condenser is perfectly clean. Not a single bug or any debris at all. I'd love to find something like a plastic Walmart bag stuck in between the radiator and condenser because that would be a "smoking gun."

If you want to see some of the actual pressure numbers that I've recorded from my testing, here is a link to my thread at autoacforum.com:

2002 Pontiac Ram Air Trans Am ac is not cooling properly

 

I also want to mention that I have refrigerant recovery equipment ordered. The recommendation from the auto ac forum is for me to recover and weigh my current R134a charge in my car. I already own a very precise ac scale that measures down to 1/100th of a pound. I own Mastercool gauges and a vacuum pump.

One of the local auto repair shops wants $100 to recover my refrigerant and tell me how much was in the system. I decided to buy my own equipment. It was probably overkill to spend all the money on the Mastercool recovery equipment but I have two other project cars in my garage that will need ac work. One is an LS3 swap into a 1991 Mustang Coupe. I've already got the LS376/480 in so it's very possible that I'll be working on it's ac system before next summer. I'm sure over the years I'll get some value out of the equipment.

BTW, I don't have the recovery equipment yet. My cc was charged as of this morning so I'm hoping the tool seller will ship it out soon.