Hello all im having some issues with my a.c in my 98 tahoe. It blows warm air while im sitting at a stop but will progressively get cooler as i drive but not that cold. I have done everything I can think of and she still doesn't work right here is a list of the things i have done In the last year or so
-replaced compressor
-rear ac lines had a leak so i replaced both front lines with the lines for Tahoe with no rear ac instead of just buying the plugs to cap off the rear ac lines and replaced orfus tube
-replaced receiver dryer and low and high pressure switch
-replaced evaporator in the dash
-took to my buddies shop and had him completely vac the system for 30 min and charged system with 2lbs of freon.
basicallythe only component in the ac system that isint brand new is the front condenser the compressor turns on and if you grab the line coming off the compresser it is ice cold so i know the compressor is working just cant figure out why its not geting cold in the truck
fan clutch is good i am totally stumped here. the system has held a charge for over a year so i know there is no leaks i don't know what else to do. any tips would be greatly appreciated.

 

Have you considered replacing the controls? We used to have a 96 ford van with a very similar issue. Turned out that the vaccum that is incorporated into the dash controls was bad. Got one on ebay for $15 and it fixed the whole issue. You might look into that as a cheap option to test. Also, the front condensor... if you havent replaced it, you might want to as another option. I just replaced the one on my suburban and that old one was in bad shape. Somehow it was gunked up and nothing was passing through the lines. If the system cant be cooled, that may be part of the issue as well. I bought mine at AutoZone for either $194 or $220, cant remember which. Try the controls first though. If the vaccum is bad, the blend door isnt operating correctly, so, in theory, youre only mixing half air with half fan air.

 

id be looking at the fans/fan clutch and condenser, when you drive you increase airflow which would bring the head pressures down and make the system work better

 

I don't know if the heater control is vacuum, could be blending both heater, and ac. My mazda had the same issue, I thought the plenum was drawing in engine compartment air mixing with the cold air. Turns out I had too much freon in the system. I know if in residential you have to high a chrge it will act as if you were low.