wwest

Thinking....

Gets me in trouble every time!

Mold and mildew odor is caused by bacterial growth due to the thin film of mositure remaining on evaporator core long after A/C use. Early morning instances of windshield fogging is from the same source. Japanese vehicles, climate control supplied by NipponDenso or Denso USA, cannot properly defog/demist the windshield.

Many modern day vehicles, including Lexus and Porsche, run the A/C compressor all the way down to the absolute minimum outside temperatures. Below about 55F the only possible LOGICAL need for the A/C compressor is to dehumidify the incoming airflow and thus to help in keeping the windshield defogged, and maybe add some minor level of human comfort.

The problem is, Lexus, or any vehicle with an automatic climate control designed by Denso, relies solely on the A/C system to defog/demist the windshield. Below 32F OAT this is a practical impossibility! Even above 32F, and upwards to about 45F, the humidity of the incoming airstream must be extraordinarily high for this practice to be effective.

To date I have recieved only two explanations for this practice, running the A/C system below 45F.

1. Running the A/C keeps the A/C evaporator coated with a thin film of moisture and that suppresses the horrid mold and mildew odor. Porsche factory represenative told me that.

2. Using the A/C system to defog/demist the windshield by dehumidifying the incoming airflow, however inefficient, and even non-functional, that might be at lower temperatures, circumvents the requirement, otherwise, to use a high level of heating to accomplish this and thereby discomforting the passengers.

Does that sound like a SANE design decision? Sacrifice the safety of the passengers in your automobile rather than discomfort them by heating the windshield when it becomes necessary.

Does anyone have another explanation to offer?

But, back to work.

How about a dash mounted switch that disables the A/C compressor clutch and at the same time enables a circuit which if the defog/demist climate control function is activated causes the airflow heating level to rise substantially along with the blower speed, virtually instantly.

If you notice even the slightest indication of windshield condensation the dewpoint spread will be instantly increased with heat and airflow once you activate the defog/demist function.

Presumiably most operators would activate the switch once the predominant ambiant temperature declines below 50F. No more thin film of mositure on the evaporator vanes,

NO MORE BACTERIAL GROWTH!

NO MORE COLD MORNING DRIVE WINDSHIELD FOGGING!

SUBSTANTIAL INCREASE IN MPG.


Oh, by the way, while Porsche does run the A/C all the way down to just above the point of freezing, on the HOTTEST day of summer if you activate defog/demist, YOU INSTANTLY GET HIGH HEAT AND AIRFLOW TO THE INTERIOR WINDSHIELD SURFACE!

Not stupid, those German engineers.

wwest

In Lexus Electronics thread

PAULGS430

Um. The smell is coming from your AC filter located in your glove box. If you look in your GS manuel, it will tell you how to remove & clean it. All you have to do is wipe it clean.
1) Open Glove box
2) Yoe should see a cover over your disc changer open it
3) remove the filter & clean it.

Paul

P.S. When you say Defogger? Are you talking about frnot or back?

wwest

The mold and mildew, dirty gym sock, odor comes from the "out-gassing" of those tiny bacterial spores, microbes, that thrive mightily and reproduce in droves in dark and dank environments with temperatures in the range of 55-70F

In other words your A/C evaporator and its surround.

The filter is there primarily to prevent some of the food from reaching these microbes and thereby retarding their growth rate.

And it's the front windshield that I speak of. If you check you will discover that on the coldest day you might possibly encounter the Lexus series will not apply ANY additional heating to the windshield in defog mode once the passenger cabin has acclimated to the system setpoint.

Once condensation has formed on the interior surface of your windshield it will take an inordinate level of energy applied to force a "state change" and convert the liquid condensate back into a gas.

That will not happen at all quickly simply with the use of the dehumidification capabilities of the A/C system, especially in times of colder weather when the windshield is much more likely to fog over anyway.

wwest

Don't try to "clean" the filter, you might be able to remove the large particles and debris, but the small sub-micron filter pores that really do the job will be quite thoroughly clogged in as little as 8k miles.

LexFather

You could buy a gas mask, minimize most all spores, lol.....maybe put a CLubLexus sticker on the gas mask...

MGS4

Um... I don't think the AC filter can be cleaned. It has to be replaced every year. You can buy the filter at the dealer, but forgive me, I think the OEM one is crappy and expensive. I bought the 3M Ultra Allergen Reduction Filter at Home Depot. Probably the best filter money can buy and cheaper too. However, you'll have to cut it to fit, which is no problem.

wwest

That 3M filter seems to be as highly efficient as the one in the Porsche 996, which means it likely needs to be replaced more often than the factory recommends.

The way I test for replacement is I hold a light up behind it, if the light penetrates well (subjective, sorry) then the filter is still okay.