05 Ls430 A/c Intermittent Cooling

[1995SC4double0]

My LS has 73,000 miles and the Mark Levinson/Nav/Climate screen. It has just started having this issue this year (since using the A/C). The blower fan is fine, but sometimes I get nothing but hot air. Sometimes I get in the car and it works fine, even with several trips a day. This morning I got in and it wasn't cooling the whole way to work, which is about 10-15 miles. I'm pretty sure the freon level is fine because when it does work, it's cold. Anyone know what this could be?

I'm not sure if I should go to my local AC/cooling business, or to my Lexus dealer.

Sometimes I've had good luck with pressing "Auto" when I turn it on rather than pressing the fan speed buttons on the display.

[Ancdmd]

It's the compressor, its locking up internally. There's really no way to predict when it will happen or not. Changing the amount of freon in the system may help, but ultimately you'll have to replace the compressor. I know because I had the same problem, took two years to diagnose.

Check the sight glass on the AC line in front of the radiator while the AC is running. It should be clear black, if you see any bubbles running through the line then you are low on refrigerant. To add refrigerant simply get a filler hose with a dial gauge and a can of plain refrigerant WITHOUT ADDED SEALERS at the auto parts store, should cost around $25. Follow the instructions and add the refrigerant, takes 5 minutes and is easy to do. This may help your compressor to kick on easier. If you overfill it then it may make the compressor lock up more often, but since it will ultimately need replacing you can't lose.

Get a Denso compressor off eBay for @$325 and pay your local independent mechanic to replace it.

[Ancdmd]

Also replace the drier when you do the compressor...

[Ancdmd]

http://us.lexusownersclub.com/forums/index.php?showtopic=72954

[steve2006]

First have the AC system checked by a professional outfit they will be able to diagnose any problems with it and make sure the correct amount of refridgerent is present, it's no good guessing as an underfill or overfill will cause problems of one sort or another.

Once you are satisfied this part is working as it should you then need to look at the flap/vent controls and that the heater flow valve in the engine bay are all working right.

Basically when the AC is set to cold the heater valve should close off the warm water supply to the heater matrix and various flaps direct the flow air over the AC condensor. Other flaps control the air flow from the dash for example from the center or side vents.

Another cause could be a clogged up pollen filter which is located under the glove box and prevents a good constant airflow.

[1995SC4double0]

Thank you all! I am taking it to my local A/C people tomorrow. I'll report back with the diagnosis.