Forever my thermostat was stuck open so I replaced that in January and the CEL went away, good. But I decided not to deal with the A/C not working until it got hot out again. Well its hot and my A/C still doesnt work. I went to Lexus today and used their fancy machine to vacuum and charge it back up to .90lbs like it says on the sticker on the front of the car and it still doesnt work. The compressor DOES get power to it but it just doesnt want to turn on. After driving out of Lexus and to the gas station I filled it up then turned it back on the A/C worked for about 45 seconds and then it quit. I have NO IDEA what is going on. Do you?

 

.9lbs? **** I gotta go check cuz I think it needs more than that. Did you add your oil charge too?

edit- So I checked, your right, so if the system is like older R134a systems it has a high and low pressure switch and it reads the coolant temp sensor to be sure it doesn't come on below a certain temperature. There are ways to check it, these pressure switches are switches NOT sensors so you can short the connector pins on the low side sensor and the A/C should kick on.

Does your fan come on when you kick on the A/C I believe that fan is wired to come on with the A/C switch no matter what. I checked mine it will even come on if you press it with the engine off/key on.

 

Please do check about how much freon. .9lbs seems low to me and if the A/C is kicking on sometimes then maybe it just needs some more freon.

Does anyone know how much freon the car needs? We tried vacuuming low side and putting in .9lbs and nothing. And then we tried high side with .9lbs after vacuuming and it gives just 30 seconds of A/C (after 10 minutes) and it was done for good.

 

My A/C has gone off and come on a few times since the last post. It usually stays on for 5-10 minutes then quits for a long time. It only worked when we put freon in the high side. But using the pressure gauges, the low side gets near 100psi and the high side is the same, with the car ON. I think the sensor is bad but I dont know where it is or how to check it. The compressor and clutch are fine because when the A/C actually does come on its perfect. ALSO we ran a leak test on the Lexus A/C machine and it failed. So there might be a leak and my guess is in highside because the pressure NEVER gets above 110psi.

 

The pressures when the compressor are not on should be close to even on the high and low side. Once the compressor comes on, the low side should drop way down and the high side come up. They will stay this way until the compressor is off for a bit, when the pressures will begin to equalize again.

The only way to know if you have the right amount of 134a in the system is to get the compressor to engage, and measure the pressures while it is running, then add or remove as necessary while measuring the output temperatures at the center vent. Ideally you should also monitor the condenser temperatures (or the high pressure side output pipe) to verify its not overheating.

 

.9 lbs is the correct charge for these vehicles as far as I've seen. (Not sure on LNF cars but its likely the same.)

Sounds like your compressor clutch may be open internally (read: Cooked) or the air gap between the clutch and compressor hub is too great. I say that because you have power and ground to the clutch as you've tested.