Ford Escape Mazda Tribute Maintenance and Repair

Since R-134a is less efficient than the freon it replaced, the loss of efficiency had to be overcome somehow.

I'll use my 1992 LS400 as an example. My 1984 T-bird's A/C evaporator had approximatly 2500 square inches of heat exhanging, metal cooling surface area. The 1992 LS400's evaporator had over 10,000 square inches of metal cooling surface area (the LS was not converted to R-134a until later, but Lexus advised me that the A/C system had been designed even with the first LS model with the conversion to R-134a in mind)

At about the same time a passenger airbag was added and then an in-dash CD changer/player. So at about the same time the A/C evaporator had to become more complex to make up for the loss of refrigerant efficiency it was also growing more compact.

Begin to sound like a sponge, maybe? Well not yet.

By 92 Lexus had discovered that the "new" A/C, designed and manufactured by NipponDenso, Denso US here, was the source of the horrid mold and mildew odors that customers were complaining about. So they came up with a solution, embed an anti-bacterial chemical onto the evaporator's cooling surfaces, KILL them suckers before they multiply.

How did they do THAT?

They coated the entire evaporator surface area, all 10,000 square inches, with a PORUS nylon film, dipped it into the anti-bacterial chemical and until the chemical leached out of the pores no mold or mildew could survive, let alone thrive.

But just guess what the result was once the chemical leached out of the pores? Now you didn't just have 10,000 square inches of surface area, you had 10,000 square inches of SPONGE covered surface area.

From about early January and into the fall or 1992 the LS400 remained parked becuase it couldn't be trusted not to suddenly and spontaneously, without any warning or indication whatsoever, completely fog over the front windshield.

By the fall of 92 I had analyzed the system well enough to begin to understand what was happening and I began religiously opening the sunroof and windows slightly each and every night once it was in the garage.

There remains a flaw to this day with the entire Lexus product line, or any automatic climate control system designed by NipponDenso or Denso US. They simply don't seem to grasp the laws of physics as they pertain to the occassional need to quickly defog/demist the front windshield and keep it defogged/demisted. More about this later.

Another aspect of the operation of the 92 Lexus, and actually many other modern day vehicles, even my 01 C4, is the fact that the A/C compressor remains operational even with outside temperatures below freezing.

The only reasonable explanation for this was given to me recently by a Porsche factory representative. He said that it is Porsche's method of suppressing the horrid mold and mildew smell, if the A/C evaporator surfaces are kept coated, continuously, with a thin film of moisture, then that that covers and suppresses the mold and mildew bacteria and thus the smell of their chemical "out-gassing".

Help for Ford and Maxda owners.

On browsing the internet you will find that Ford, if you complain mightily, will "cure" the mold and mildew odor problem by installing a product like, or maybe this actual product"

http://www.airsept.com/eed.html

I understand that many Saturn models come from the factory equipped with an equivalent device.

Mazda, in australia, still makes use of the anti-bacterial chemical coating as I described earlier, so for you Mazda owner's maybe you should be prepared for episodes of sudden windshield fogging and heavy mold and mildew odors once the chemical leaches from the "sponge".