When I bought my LS400 about 2 months ago, the car had already been converted to R134a. The compressor was making a very slight grinding noise like the bearing was starting to wear out. The A/C always worked great on the highway at 45+mph, but around town it was just somewhat cool. I figured it was just low on refrigerant.

Fast forward to this weekend and I make a trip down to Florida. The A/C worked the entire way down, nice and cold. I even noticed in Florida traffic when I finally got there that the a/c was staying very cold and working really good. Well I park it over the weekend, then pick it up at the valet 2 days later to head home. I drive off for a few minutes and then put the A/C since I was on the highway and it would be nice and cool. No A/C! The compressor wasn't even turning on.

Got home last night and ran the A/C diagnostic codes as per lexls.com. Nothing shows up, just a 00 (indicating system should be fine?). After reading a few threads on here I decide to test if the compressor will even turn on. I got underneath the fuse box and pulled the MG Clutch relay and bridged the two copper terminals with a wire. The compressor immediately turns on, so it should just be low on refrigerant right? I put a gauge up to the low side of the A/C system and the pressure is at about 15psi. Great, hooked a can of R134a up to it and got the pressure up to a nice 35psi. A/C is still blowing warm! I can hear the compressor turn on everytime I turn on the A/C, but no cold air whatsoever, even at highway speeds.

Does anyone have any ideas what could be wrong? 95 degrees and no A/C sucks!

 

u have a leak in the system, have it checked out

 

And why would the a/c not work at all when its fully charged regardless of a slow leak?