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

Tony

Im in the southwest and here the dealers have been removing the rubber engine mud guards from the the front wheel wells to help keep the air conditioner running cool. So far it is working but I worry that the engine will be exposed to more dirt this way. We hit 153 degrees inside the vehicle with direct sun in the interior of the GX and the air is really fast as far as cooling. Our humidity is only 8 percent with 120 degrees outside.

Humid GX

I am positive that the lack of a/c performance has nothing to do with air circulation within the engine compartment via removing the wheelwell panels. If you were to advance this theory to other vehicles, then Lexus or other manufacturers would have not built vehicles with the wheelwell panels. However, the air circulation around the condenser is paramount which is not the problem with the GX. If you were to compare the a/c performance with the ES, LX etc. there is no comparison although all these vehicles have "contained" front wheelwell's. Further, if you were to extend this wheelwell theory, then you would also see many GX's have a tendency of overheating causing Lexus to remove these wheelwell panels. Thanks for the thoughts nevertheless.

Any air conditioning or HVAC specialists out there to provide any thoughts, comments or concerns related to this thread??? And would anyone out there have a pix of GX evaporator core compared to that of other Lexus models to determine, in fact, whether the GX's evap core is truly too small?

CivicFerio

I have my A/C woes to share also. When the cabin temp reaches the set temperature. The air coming out of the vents blows warm and cold in a 1min cycle. It is like the A/C is over correcting itself while trying to stabilize the cabin temperature. I find this sort of anoying because I'm always playing tag with the temp settings. My 02 Honda Odyssey when you set it at 72° you don't need to change it day or night.

I took my GX to the dealer to assess the problem and they told me that my GX bought in Jan 03 had the A/C corrections already done to it.

The GX's A/C controls monitors both cabin temperature and sun light intensity and make fine adjustments to the fan, A/C and heater settings. I have observed that in day time the A/C never goes below II fan speed even when the desired cabin temp is reached, and during the night is the only time I see the fan speed go to I speed. So the system knows when it's hot or cold outside but it's the cabin that it is having touble with.

I think the problem is not in the evap but it could be in the condenser. When the A/C switches off even when the desired cabin temp isn't reach (like on a hot day), means that the high side of the A/C line has reach a pressure too high and the pressure switch has turned off (override) the A/C compressor to prevent damage to the system.

High side pressure getting too high on the A/C is usually caused by 3 things. First is the A/C refrigirant has been over charged. Second, the expansion valve is clogged. And third, inadequate cooling of the condenser, you can test this by driving the car over 45+mph or reving the engine to 2000rpm to let the engine fan pull cool air through the condenser. If the A/C starts to cool BINGO! you know it's the condenser not getting air.

Try to manualy take over the A/C controls by lowering the temperature to 60°, recirculating the air in the cabin and fan speed on high or middle. And adjust cabin temp through fan speed.

Hope this helps, keep us posted. Thanks

Charleston

03 GX470
02 Odyssey EX-L Nav
99 Civic EX
90 CRX Si

Humid GX

CivicFerio,

The A/C Technical Service Bulletin for the A/C was published/dated in January 2004 which as I indicated replaces your condensor and expansion valve charging a total of eight hours to warranty service. The original condensor supposedly was inferior regarding it's cooling capacity of the refrigerant. You need to have your dealer pull up this TSB and you will be amazed as to it's depth of replacing parts to also include putting foam type liners around the fresh and recirc flaps. Since you indicated that you had yours checked in January 2003, your GX may will this upgrade and, with emphasis, the bottom of the TSB says in that it will only be installed after "consumer complaints regarding cooling".

As to your comments regarding AUTO settings etc., the high forty degree vent temps are done in manual mode, second fan speed setting with Max Cold. Nevetheless, this a/c system is severely lacking in it's capabilities. Since the evaporator core is allegedly lacking in size, I will ask the dealer/Atlanta engineer if another Lexus model's evaporator core can be used in the GX and/or when will the Lexus engineers design a new evaporator core to be used as a replacement.

Should the GX succumb to 90% plus humidity coupled with 90 degree ambient temps, you should opt to hang a window a/c unit (i.e. 6,000 btu) from the back window...

Other thoughts, comments and/or concerns?

brent0226

Here in Texas, the only problem we have with the GX's AC set on Auto is it is too cold. It always seems like the AC is just blowing too dang hard. We always have to set it up to like 76 or 78 and push the vents away. And for those of you suggesting to just operate it in manual mode: Auto AC is one reason to buy a luxury car; people with the VW Touareg had problems with condensation forming on the windshield while in Auto mode, and the "solution" was to operate it in manual mode; you buy a car with auto AC for a reason. Lexus's Auto A/C, in my experience, gets a thumbs down .

The Auto ACs in our Jetta and F150 work perfectly on Auto set at 68 degrees; the system always keeps the desired temperature without the need to ever adjust it. Maybe Lexus should study theirs...

powersofal

I have a 2003 - with a June build date. I live in the deep south like the original author.

I have found setting it to 76 on my side and 78 on the passenger side with the vents pushed away. When the GX is sitting outside for a while in the sun - the cold air is plenty. Then as it cools down it adjusts very well. I think it's really much cooler than 76 in the passenger compartment. I have tried every other setting just to find that I go back to this one. When I set it lower it seems to do what the other participants in this chain fine - blows "HOT" air- that is unacceptable to me when it's blazing hot.

But my wife has a Volvo XC that will freeze you out of the car - but thats the only thing that continues to work correctly on it.

So I have adapted to the GX very well but my oldest daughter now drives the oldest Lexus in the family and we have always just left that one in the summer set to 73 and it works great.

Go figure!!!

O' one other point I found to be true is that having the sun roof opens messes up the entire system. The feature of opening all the windows by with the remote also confuses it somewhat. So the best advice is to set it and leave it.. I know it sounds strange!!!!

Hope this helps!!!

Humid GX

Powersofal and/or others,

If possible, can you put a digital thermometer into the center vent, using MAX COOL, RECIRC and low/medium fan speed, and tell me what the lowest temp you see along with the ambient temp as read on your dash? For comparision, my GX will only get to 48 degrees with temps north of 80 degrees. As a matter of fact, if it's 72 degrees, she will only get to 47 degrees which indicates many possible problems i.e. condensor, evaporator and/or the four temperature sensors. Unfortunately, the dealer is "riding the fence".

As a benchmark, with 95 degrees ambient temp, with RECIRC, MAX COOL and medium fan, I drove a dark blue GX with 44 miles. It could only get down to 50 degrees as measured at the center vent. The service manager is perplexed yet she sits on the dealer lot awaiting an unknowing buyer.

At this juncture, something is gravely amiss (emphasis added) with the GX's a/c system in high temp, high humidity environments. The A/C Technical Service Bulletin distributed in January 2004 did absolutely nothing to the cooling effect...nothing. Why would Lexus engineers try to modify the a/c system when thy can look across other Toyota/Lexus models to see what works best in other models? Some Tahara engineer(s) asshide should be hung on the wall for this absolute design screwup.

If you live south of the Mason/Dixon, I would strongly suggest you drive this vehicle in the afternoon and make sure the center vent temp is 39 to 42 degrees, the normalized level for any generic a/c system with R134a as refridgerant.

Kash

yeah at 76 my vehicle is abit chilly in houston.. this during the summer ... and my ac works great

CivicFerio

Here is my vent temps taken today here in Los Angeles. Humidity at 26%, ambient temp around 93° taken with the same thermoprobe used for the A/C vents. Car was traveling around 50mph and vent temp was taken after 10mins of travel. Lowest temperature observed was 47°F and highest was 59°F and cycles between those 2 numbers.

Humid GX

Civic...

Thanks for the validation via your pix's.


Question: Has your GX been retrofitted with the new condensor, expansion valve etc. per the Technical Service Bulletin that came out in January 2004? This supposedly was to cure the a/c performance issues in high temp/high humidity climates but had no effect on mine notably at 80+%humidity.

And do you feel at 26% humidity at 95 degrees that the GX cools adequately compared to other vehicles you have owned/driven?

HumidGX

CivicFerio

According to my dealer's service consultant, my GX bought in Jan 03 has the A/C up grades already done to it at factory. So far I feel my A/C is adequate.

Today, early morning at 3am I got the chance to test it out again (yeah I had a long night). Out side temp around 70°F with the A/C on, vent closed, temp set at max cold, fan on medium. The best the A/C could do was the same 47°F no difference at all when the ambient temp was at 95°F. But I feel very comfortable to slightly too cold even.

My 02 Odyssey easily got down to 42°F with out breaking a sweat even when sitting. I've seen a couple of R12 refrigerant cars from the early 90's reach vent temps mid to low 30°s!!

My observation is that on my GX the cabin temp is fine but it's the radiant heat from the dash or the seats (I have the dark gray interior) that gets me. Tinting the side windows or even the windshield might help in this case. Try the window tint called V-kool.

Regards,
Charleston