Ac Stops Blowing Cold After An Hour

[rhkwon]

I've got a 1996 ES 300 with 115,000 miles with original compressor. The problem is sometimes the AC blows great and cold and other times it will gradually stop blowing cold air. When this happens, I push the AC button to see if the compressor kicks in and it does'nt. The AC light does not blink when it's not blowing cold air. The car has been recharged a couple of years ago.

So, is it the compressor? Is it a relay and if so how do I check it and where is it? It's frustrating!

[1990LS400]

Does the system have adequate refrigerent in it? It is not uncommon to have to top up the refregerent in an older car at least once each year. The refigerent level in an R-134a system doesn't have to drop that much for the system to stop producing cold air -- at least that is what my repair shop tech told me last summer when he topped up the refigerent in my 00 LS to get it working again. The system in my car apparently has a slow leak but the tech was not able to find it after adding dye and using a blacklight.

[rhkwon]

Does the system have adequate refrigerent in it? It is not uncommon to have to top up the refregerent in an older car at least once each year. The refigerent level in an R-134a system doesn't have to drop that much for the system to stop producing cold air -- at least that is what my repair shop tech told me last summer when he topped up the refigerent in my 00 LS to get it working again. The system in my car apparently has a slow leak but the tech was not able to find it after adding dye and using a blacklight.

Yeah, from what I recall the mechanic saying last year, there was a slow leak. He put in some dye. But if the refrigerant was low, how could it still be producing cold air? It seems sometimes when it gets really hot during the day, it will stop producing cold air. Not all the time but every once in awhile.

[1990LS400]

Yeah, from what I recall the mechanic saying last year, there was a slow leak. He put in some dye. But if the refrigerant was low, how could it still be producing cold air? It seems sometimes when it gets really hot during the day, it will stop producing cold air. Not all the time but every once in awhile.

I can't explain why you are sometimes getting colder air but mine did the same when it was low on refrigerent. R-134a is cheap so you might as well charge it up and see if that fixes the problem.

[rhkwon]

OK, found out the expansion valve is bad and needs to be replaced. It's located underneath the glove box. $60 part plus 3-4 cans of freon. Total should be about $250-300 including labor.

What happens when the valve goes bad is that it freezes up, literally and when it freezes up, no cold air can be moved. Has nothing to do with the heat of the day but stops working after an hour or so. If you wait an hour or so, it melts and works again.