I have 2004 GS300 and lately AC started blowing a hot air so I've thought that it was low on the freon. I've picked up AC pro kit and proceeded to the refilling process. I have noticed that when I turn the AC on, the compressor always stays on and it has the proper amount of freon in it along with the ambient temperature.
I have checked the relay for the compressor so far and it is working just fine.
What could be the problem?

 

Maybe compressor is going bad? When I took off the compressor relay, the clutch does not engage. My car has 220k miles and has the original compressor.
Also it's blowing hot air through all vents so I do not think it's the servo.

 

Do you have a gauge set? When mine failed the compressor ran, but made no pressure. Had to use a gauge set to see the failure.

 

Thanks TrueGS. I'm going to pick up one from Harbor Freight. Maybe my compressor clutch is still engaging but not making enough pressure. I just pulled the AC codes and the display shows 00 no codes related to AC.

 

Update:My AC works perfectly after replacing expansion valve and drier.
I've rented Autozone gauges and vacuum pump to get the job done($360).
I've spent $23 for Denso drier kit, $17 for aftermarket expansion valve and $24 for 2 cans of Autozone r134 with PAG oil for the reference.
Considering the situation with my car(original compressor, 223k miles and 2004 vehicle), it was very worth it in my opinion. I got AC for this coming summer! No leaks neither! Now I'm seeing how long this current job would last. As always thanks CL.

 

My compressor went out at about 130k. One of the few things that actually needed replacement because it went bad

 

Question: Did the dash have to be removed to replace the expansion valve? I'm seeing mixed responses.

 

No, but you are gonna find yourself in very uncomfortable position to do so.
My expansion valve was completely covered by factory rubber like material for in case of leakage. It was easy to peel off. After that, it was a piece of cake. Whole process took me about 30 mins. You can locate the expansion valve by removing the kicker panel on driver's side dash.

 

Thanks a bunch!

 

Sorry, wrong thread.
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Someone has posted a pretty good YouTube video covering this project. It’s always helpful to see someone tackle a project before doing it yourself for the first time. I don’t have a link for you but a am sure you can find it. Or let me know if you can’t and I will see if I can locate it.