Evaporator cleaning

The majority of the comfort does not come from cooling the air. It comes from removing the humidity. That's why air conditioner compressors run in winter when we select the "defrost" mode. It removes the humidity so it does not condense on the cold windshield.

That condensation is the water you see running out of the drain tube and onto the ground just left of and behind the right front tire when the system is running in the summer. That water on the evaporator traps pollen and dust, and those get washed off as the water runs out. When you pull a heater box apart, the only time you will find built up dust is when the system hasn't been working for years.

The only spray you will find at dealerships for air conditioner systems is an odor neutralizer, and that is only used when mold has formed in the heater box due to that condensate not draining freely. The product is sprayed into the vents from inside the vehicle and into the air intake under the hood or in front of the windshield. When spraying into the air intake, run the fan on the lowest speed to draw the spray in.

Evaporators have very little buildup of anything even after twenty to thirty years.

Yup. I agree.

I've never tried getting to an evaporator by removing the bower motor. I doubt it would be that easy. Normally you have to discharge the refrigerant, disconnect the heater hoses and AC lines, then remove the dash board to remove the heater box. Once removed, the heater box has to be disassembled to get to the heater core and evaporator. It's a really big job that most professionals run away from.

You're trying to do something that none of us has ever attempted or heard of anyone worrying about, My fear is you're going to cause a lot more trouble than anything you think you're going to fix. Taking dash boards apart has a way of resulting in elusive squeaks and rattles, and often things that don't work resulting in having to take everything apart again. If you're really determined to find dust to clean, take the side trim panels off and look behind them. Watch out for sharp metal points and screw tips so you don't cut yourself. If you wipe a rag around in those areas, you'll be amazed at what you find in even the cleanest of cars.