got my car back today. The Lexus techs said it was fine. they checked it out and everything seems fine. ehh i dont know what to think about that.

 

Certainly.. the main fix, is really the easiest. All it is, is a simple evac and recharge of the system. Be sure to hold vacuum on the system for a while to boil out the moisture. Then charge to the low side of the spec.. so.. if the capacity spec is 1.72 - 1.95, i would put 1.75 in, keeping to the low side of the spec. The other fixes, which are a bit harder, involve insulating the low and high side lines going to the evaperator. Id just stick with a evac and recharge.... Or if the light doesnt bother you, just stick with the way it is..

 

how do you know so much about air conditioning

 

Im an ASE Master certified lexus tech... Been with Lexus for almost 4 years...

 

RT Camaro,

My 2004 GX had the air conditioner Technical Service Bulletin (TSB) dated January 2004 performed two weeks ago wherein Lexus replaced the condenser, expansion valve, added enhanced insulation to various high/low refridgerant lines along with adding seals to the Recirc and fresh air flaps. Nevertheless, the effect of this TSB did not enhance the cooling effect whatsoever given the high humidity environment. With an ambient temperature at 90 plus degrees with 90% humidity, the best vent temperature has been 47 degrees which easily fails the "comfort factor". Other Lexus models under the same conditions can easily get high 30's / low 40's in vent temperature i.e.2004 ES 330

If you live in Chicago, you would probably not notice the GX lack of cooling but if you live in Atlanta/Orlando, the GX's a/c simply cannot compete with temperature/ humidity in the southeast.

Given you experience with Lexus, do you have any suggestions and have you seen this problem with the GX?

 

You are correct... while i havent personally seen the lack of cooling in hotter climates, i have, however, seen a few tricks. One of which is removing the plastic/rubber inner fender flaps. The smaller flaps that cover the gap between the wheel well and the engine compartment... the main problem is getting the heat out of the condensor. The airflow to the condensor is adequate, but the hot exiting air has nowhere to go... We have done this mod, and has success with it. Your vehicle may have come from the factory with the flaps already removed, but its worth a shot to check. BTW: a 43 degree drop between ambient temperature and center vent temperature is perfectly acceptable, however, i completely understand your concern about it not being cool enough... it wouldnt be cool enough for me either

 

RT,

What is interesting is that no matter what the ambient temp/humidity level (usually 80+%), the vent temp with RECIRC, manual mode, medium fan usually flatlines at 47 to 48 degrees. Thus, if it is 72 or 92 degrees, the vent temp will get to 47-48 degrees, NO LOWER even in sunny or rainy conditions. Thus, this leads me believe many troubleshooting scenario's:

a) a/c temp sensor by the right knee;
b) evaporator temp sensor;
c) electronics in the a/c amplifier;
d) evaporator is too small i.e. engineering flaw;
e) condensor i.e. to small;
f) solar sensor on the dash (long shot);
g) expansion valve not designed correctly?

The dealer brought R134a down a notch below spec but the effect of this was to feel the compressor cycle i.e. move from 47 degrees to 49 degrees vent temp. There was no real effect of this.

Thus, what is puzzling is why this vehicle cannot achieve the same cooling effect of other vehicles. If the condensor cannot remove the heat, then how come other vehicles don't require to removal of the wheel well flaps? Thus, are you saying that all (emphasis added) other vehicles are more efficient as to movement of air underneath the hood than the GX?

Anything you can offer as to possible solutions prior to discussing with the service manager again?

 

hmm... im just about a puzzled as you. we dont see this problem out here in california very often, if ever. when i get back to work this week, im going to speak with my diagnostic specialist, as well as my service manager, and see if they have heard anything about it. im sorry that i havent been able to help you more, but the best of luck to you in getting your issue resolved. i agree that the GX should be able to achive the same center vent temps as other lexus vehicles, however, maybe the rear a/c should be taken into account as a factor.. possibly a compressor that cant keep up with the demand? best of luck to you...