I have a 1999 TL. The AC starts off ok, then it slowly gets warmer until it is probably only about 78 degrees. I have replaced the low pressure switch and vacumed the system and recharged it. When I measure the pressure it bearly gets to 25PSI on the low pressure side. I have put the 22oz of 134a in it, so I don't believe it is a charge issue. I removed the cabin filters the other day and they were very dirty, but it isn't any better now. Does anyone have an idea what my issue might be?

 

Post this in the 2G section because then they will give you the answer that you are looking for.

 

From your description, I would guess the heater core valve or blend door is somehow gradually opening and raising the delivered temperature of air.

Check your evaporator outlet line to see if it's cold and sweating. If yes, then cooling should be good.

Try manually locking the heater core valve closed and see if cooling improves.

A pressure of 25 psi on low side is good and should deliver cool air,...if the high side is high enough, generally 2.5*AirTemp(F). Low side only pressures are not adequate to be sure of charge level, but your's sounds like something besides charge level.

good luck