Humid GX

My GX had the air conditioner Technical Service Bulletin (TSB) 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 in vent temperature i.e.2004 ES 330

Interestingly, today Lexus admitted that the "evaporator core" was unfortunately designed TOO small given the cabin space of the GX, thus it doesn't have the capacity to remove the humidity from the cabin and does NOT have enough cooling surface to provide sub-40 degree vent temperature. 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 these environments.

Thus, has anyone on this board discovered a solution to this underpowered GX a/c system notably in the southern states? Or any other advice as to solve this problem?

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2004 GX Blizzard Pearl
January 2004 Build
Pimped except Lexus Link
New driveshaft
3,000 miles
47 degree best vent temp-90 degree ambient/90% humidity

HarrierAWD

I suppose you could keep the recirc button on.... until the cabin is cool enough then turn it off. Otherwise the A/C is gonna stink.

Yes, humidity is a big factor for comfort. See the banner below taken somewhere near Page, AZ. At 0% humidity, even 77F feels chilly. I normally keep it at 70F.

gserep1

Hello,
I lived in Louisiana for half of my life, and I can attest to the effects of humidity on evaporator coils on air conditioning systems.

The old R-12 systems with chlorine provided sufficient cooling, but since 1993, we have been forced to use R-134A non-chlorinated refrigerant. One of the prerequisites for R-134A is that the A/C components have to be 30% larger to compensate for the 30% reduction in cooling efficiency of R-134A. Thus, the manufacturers SHOULD design their systems accordingly...especially on luxury, high dollar vehicles.

Having COLD air conditioning is MANDATORY in cars of this caliber. I have a 99 GS4 now, and it seems to have the capacity to provide cold air in the south....(we were just there a month ago, and it did fine). It did take a while longer than it does here in California, and I can see the need for more frequent filter changes to minimize the buildup of mildew-smelling coils. I do not know of any other refrigerant that would be suitable and compatible to our A/C systems. R-134A is for all intents and purposes, a "stop gap" refrigerant, until the next new chemical comes along. The new replacement is bound to be years in the making.

My wife wants a new GX. I was not aware that there was an A/C cooling problem in hot, humid climates. There should be a large enough surface area in this big vehicle to accommodate a large enough evaporator to do the job. As someone alluded to earlier, in dry climates the GX seems to work fine. I do travel a lot in southern regions, so maybe this is a cause for concern prior to purchasing a GX.

I don't know how Lexus would address a problem specific to a given geographical location, but if enough people complain about it,. they may look into it.

Humid GX

gserep1.

Thanks for your reply.

While my 04 GX was at the dealer as they studied it's deficient cooling capacity, they gave me an 04 ES 330 which performed beautifully with ambient temps at 95 degrees with 90 plus humidity. After five miles of driving 40 mph, I had to set the fan setting to the lowest fan setting as it blew cold DRY air at the center vent. If the GX could do this, this post/thread, of course, would not occur.

The Atlanta engineer who drove my vehicle agreed that the center vent should attain at least 42 degrees compared to mine at 48. This six degree difference is exponetial (sp) when it comes to cooling.

As I posted on the GX forum, owners of the GX in the southeast may have to hang a 6,000 btu a/c window unit from the back side window....

Joking aside, this a/c system should perform amongst the best of all vehicles. Not unlike the driveshaft woes, Tahara may have spent more time designing the headlights as opposed to interior climate comfort under all weather conditions....

saber

47 degrees from the center vent is totally unacceptable and I have a very hard time believing Lexus could make a major design mistake like that because Toyota's own published AC performance standards call for 37-42 degree center vent temperatures, even with R134a refrigerant.

I suspect the problem your GX has is limited to your particular GX. So to confirm whether or not this is the case, you'd need to test the center dash vent temperature on another GX. You can get thermometers like this one http://www.saber.net/~monarch/accold.jpg from Walmart for $12 bucks. If other GX's have the same problem then I would seek arbitration unless Lexus can provide some assurance that the factory is working on a fix.

Now if the other GX's you check put out at least 42 degree air then you have proof the AC system of your particular GX has a mechanical problem.

I have rented a large number of 2003 & 2004 Camry's and Corollas and they all put out 39-42 degree air
from the center vent which confirms temperatures at or near 40 degrees is still Toyota's design standard.

Humid GX

I do have thermometer similar to the one you show. It is buried six inches into center vent inches away from the evaporator core.

I wholeheartedly agree about the high 30's, low 40's vent temp but I am only able to attain 47 to 48 degrees. I am starting to think that there is sensor switch that causes evaporator core to only maintain this 47 degrees but I am not a HVAC expert thus I can talk fluently regarding this as it relates to the GX.

The service manager indicates that another GX has a center vent temp of 48 degrees, thus he wants to conclude that this temp level is normal for a GX which is poppycock.

Could you send me an internet address indicating that 39 to 42 degrees is the Toyota/Lexus standard you referred to?

HarrierAWD

Would pumping more R134a into the system help? Or would that damage the system?

"Poppycock" ROTFL Haven't seen that word in a long time.

nthach

too much R134 will make the highside pressure go up.