The airconditioner on my 2000 LS400 is only putting out 60 degree air when the temp is turned all the way to "COLD". This is on a 90 degree day. It used to put out about 40 degree air. The Toyota shop evacuated the system and rechanged freon with leak detector, found no leaks, but still only cools to 60. They say it may be the expansion valve, evaporator, or something else (which I forgot). Does anybody have a clue as to what may be causing this. The compressor and clutch seem to be OK. This is the first and only problem I have ever had with this car which has 124K miles and have owned since new. Will appreciate any ideas before I let Toyota start tearing out and replacing stuff.

 

I'm not going to speculate on the cause but it sounds like you need to take your car to a shop that knows how to follow the diagnostic procedure which should indicate the cause of the problem.

 

maybe I can be of some help here, I am not a world class Lexus expert, but I am a world class auto A/C expert.

your Lexus has a Nippondenso 10PA20C compressor, very reliable, could be getting weak, but highly unlikely.

Lexus LS series doesn't have ANY common A/C problems, so no pattern failure.

the first step is to find a really good A/C shop, the best one I know in America (Burleson, TX near Dallas), owner/guru Paul just passed away


someone competent has to thoroughly evacuate the system and WEIGH IN the exact Lexus specified charge of R-134a in order to get any meaningful result, EVEN if the system has a leak, it won't have leaked so fast that it shouldn't get icy cold right after the correct charge is installed.

THERE IS NO KNOWN WAY TO CORRECTLY CHARGE A CAR VIA GAUGE PRESSURES, IT MUST BE WEIGHED IN TO BE ACCURATE.

once the correct charge is introduced, the gauge numbers will tell you a lot, but first a couple of things have to be checked so that the high and low pressures actually provide meaningful info:

1. is the electric condenser fan working and coming on at the proper temperature?
2. is the condenser free of any obstruction, heavy bugs or a plastic Wal-mart bag can cause just the problem you have.

then what are those high and low pressures?

if the low pressure is high and and the high pressure reading is low, then you likely have a worn compressor (and a worn compressor cannot achieve enough compression ratio to adequately cool the car)

if the low side is going down to near 0 or into a vacuum, that is likely a clog which is likely at the expansion valve (the only sharp tiny restriction in the system, easiest place to clog) - this would necessitate an expansion valve replacement (cheap part, but labor intensive)

if the high and low side pressures are both high, and the charge is correct, then you likely failed to find that obstruction or failed fan in the condenser area mentioned above.

also verify that the recirculate system is coming on and working correctly (in 90 degree heat, the fresh air setting will never put out cold enough air, due to sun load loss through the marginally tinted windows)

hope this helps!

PS - NEVER EVER get talked into any refrigerant substitute - anything beside PURE 100% good old 134a will not perform to Lexus specifications for getting you cold, no matter what the hucksters of "improved" or "modern" refrigerant replacement snake oils try to sell you on!