did you check the antifreeze…lexus cars will not blow cold air if antifreeze is low & th3 engine temperature doesn’t change

 

Often, refrigerant leaks are small and slow. AC blows cold until refrigerant reaches a critical level, then there's no click from the AC clutch kicking in. The refill can is a good diagnostic, if AC works after adding refrigerant, you need to bring to shop to have leak repaired and have the system cleared of air(vacum drawn) before clean coolant is added. Often, the Schraeder valves leak slowly. These are the valves inside the threaded coolant ports with screw caps on top. If you hear a psssst when removing the screw cap, there's a leaking valve there. Good luck.

 

To update this.... Brought car to dealer, turned out it was the pressure sensor that was defective. I just bit the bullet and paid to have them replace it. Sensor got replaced, system got recharged + dye, all is well now and working like it should. Wasn't cheap but at least I got to toy around in a RX350 loaner for a day and a half.

 

How much did you pay?

 

About 700, although they at least extended me some 10% off coupon. I could have probably had my shade tree guy deal with it, or at least part of it, but was just sick of not being able to use the car.

 

The reason I am asking is because I have a AC leak somewhere. I am trying to get an estimate to find the leak.

 

Anfanger, How do you know it's a leak, it's best to just ask for a diagnosis. make a couple of calls to independent repair shops for a quote. The $700 above was for a replacement part as well as diagnosis, meaningless for your needs.

 

Because refrigerant pressure drops with time making me to recharge the system over and over again.

 

Have you tried a leak detector dye yet? Not on the LS, but in the past have used a kit that contained refrigerant with UV dye in it and also included a UV light and a gauge on the trigger. My friend did not have a garage, so we started late in the evening and by the time the system was charged it was dark. Worked like a charm, as we found the leak on a hose fitting in a matter of minutes.

 

Makes sense that there's a leak. Hope it's something inexpensive like the schraeder valve. I'm not aware of needing to use Techstream software, but doing a search on the forum is a good idea.

 

These are the specific ones for our cars. I changed mine out a few weeks ago. I could hear a brief hiss every time I took the plastic H / L caps off.
https://www.ebay.com/itm/222517305401

Before installing I recommend compressing the new Schrader valves with your fingers to check each spring tension. The first kit I ordered on amazon had a defective valve. All of the new refrigerant escaped in a few seconds. Upon inspection the new very leaky valve had a spring that was noticeably weaker. Amazon reviews indicated some were defective as well.

 

I had the same thing happen to me when I started to look for a leak after reading this thread - a brief hiss upon removing the caps. Do high and low ports use the same type valve? To me, it looked that the high port has a bigger valve than the low port.

 

The valves are different sizes for sure. A local parts store is a safe and affordable bet. They'll know what sizes you need and let you exam them for function. It's something that smart mechanics always replace when opening/draining the freon system. O-rings are another inexpensive failure point. I wouldn't change them unless they leak though, IMO.

 

High and low valves are identical. The size of the ports are different but the Schrader valves are the same.


The easiest way for me tell them apart from other valves is the number of threads on the screw part. They have 6 or 7 threads with black o-rings. The small diameter end is a spring.

 

I was wondering why would you buy aftermarket if OEM costs around $2 per piece?