Intermittent A/c Problem

[LennyF]

I have a '97 ES300 with an intermittent a/c problem. After 15 to 30 mins of driving, (sometimes longer) the a/c gradually starts blowing warmer.

I had the coolant charged but that didn't help. After the car has been off for several hours and re started, the a/c works normally.

I suspect it's in the control unit that mixes the warm & cold air.

Any help or suggestions?

[lexis lexus]

LF,

I don't think it's a climate control system prob, if the blend door was getting stuck open, it'd be luke cold all the time, and you'd prolly hear the tell-tale clicking under the dash as the door tries to close. I suspect the compressor myself. What would be good to do is take it into a shop that has a machine that can test the system WHEN it's not working well. Some places will do a free AC check, and can help diagnose the problem.

Might also want to blow out the water drain hose, that's an inexpensive job and might solve the problem.

LL

[LennyF]

I have taken it for service, (when it was not blowing cold) the coolant was slightly low. The typical scenario is when it's been turned off for a while, then restarted, the a/c blows cold again. In the past months it would go several days to a week or more and work fine, now it starts blowing warm, but not right away, just about every time we go anywhere.

Sometimes just before it starts blowing warm I hear a strange sound from under the dash. Hard to describe but I think it is the sound of an air controlled damper or butterfly. This sound does not always occur, but when it does it always starts blowing warm. Once it starts blowing warm it does so for the rest of the trip.

I'm trying to give as much info as possible....and suggestions?