HVAC

salmoncheese · June 7, 2018

Hi my '95 Lexus ES300"s A/C works fine initially, blowing very cold air. After about 15 minutes the system does not cool at all. The car has only 78000 miles. No work has been done to the HVAC system. I have owned the car since 2010 when it had less than 15000 miles and I am sure the previous owner never had problems with the HVAC system. Could it be low refrigerant or a malfunctioning expansion valve? Any input will be appreciated. Thanks

gbhrps · June 7, 2018

salmoncheese,

A 23 year old car ...... most likely needs its refrigerant recharged. With that low mileage at that age, it most likely has one or more seals in the system that have dried out, shrunk or cracked and have allowed some of the refrigerant to leak out. Its time to have a good service tech check the entire system out and recharge it.

salmoncheese · June 8, 2018

Thanks Gene, for your input. The thing is that it fails intermittently. I drove around today and it worked fine. I had to turn up the Temp. (70C to 73C) The outside air temp. was 84C. Thanks again for your suggestion. I will have it looked at soon. Cheers! Sam

gbhrps · June 8, 2018

salmoncheese,

That intermittent statement you left out of your first post suggests another issue that was present in that generation ES.

There is a relay in the engine compartment fuse box labelled "magnetic clutch" (I believe) that turns the AC compressor on and off. When it went bad, your interior fan still blew air, but the AC compressor wouldn't turn to move the refrigerant = no cooling. It usually made the dash AC button light flash repeatedly. If your relay (less than $20 to buy) is cutting in and out that could explain your problem. There is an updated part number for that relay meaning the newer one fixes the issue the old part had and shouldn't ever fail in the future.

You still could have an issue with a temperature sensor or a faulty mixing door actuator, but I'd start with my first two suggestions ... and have an AC expert (not necessarily a Lexus one) check the system out.

Gene

salmoncheese · June 9, 2018

Thanks Gene, it seems to be doing fine now, but I will have it looked at by a professional if it acts up again. The relay in the engine compartment fuse box you are referring to, is labeled A/C. It is a green cube. I will replace that first if the system malfunctions again. Thanks for your help and sharing your expertise. Sam