Radical Idea ? Cleaning A/C coils inside Heater box
 

(W124) Ok, I know I will sound like a crazy question. I have terrible allergies, and some contamination in the A/C Heater Box. You know the score. I have tried running Ozone trough the system, and that did help. Tried every spray can and foam - for years - with no real improvement. Even tried the $100 Liqui-Moly Compressor-based system...long tube with tiny spray nozzle, shoots disinfectant through all the ducts.

Great idea, but still won't get deep into the tiny A/C coils.

There is currently NO complete solution to the problem So I don't use the A/C or heater.

My (possibly 'hare-brained') idea...Since the heater box is "water-proof" - to "some" degree - 'sealed', with a drain (at bottom)....my idea was: Fill the entire box with 1-2 gallons of cheap Hydrogen Peroxide...fill it up over the top of the coils. Peroxide will kill (oxydize) every organic molecule in there (mold, etc). I've used it for years to wipe out allergens, fogged it even. ... Let the box drain out... then run the heater for 30 mins. It's shouldn't corrode or rust anything as long as it's drained and dried fairly quickly. Question is: "Would it mess up any other part of the A/C mechanically?" It's just a sealed, waterproof box with a coil and coolant pipes, right?

Any help would be appreciated. Summer is coming!!

It's not a sealed box. Good luck filling it. Bad news for you too: EVERY A/C IN EXISTENCE has mold and mildew in it. It's part of the territory, you make a wet environment, nasties grow. Depending on how much you want to tear your car apart, you can maybe fit an HVAC box from a late 94/95 model with the cabin filter, but that's the most you'd be able to do.

Radical Idea ? Cleaning A/C coils inside Heater box
 

Use a foaming cleanser. It connects to the drain tube and fills the entire AC system with cleansing foam. I use two cans. The stuff that comes out is gross.


Lubegard 96030 Kool-It Evaporator and Heater Foam Cleaner https://www.amazon.com/dp/B0007PHD0S/ref=cm_sw_r_cp_api_i_.kRTEbZJ0P31S

GM once had a kit (probably 30 years ago now) that could be added to their cars to run the heater fan for a certain amount of time after the car was shut off to dry out the evaporator. It was brought out to be added to cars whose customers complained of AC odour.
Perhaps after you have the system cleaned out, you could rig something similar to limit growth.

MB dealerships use a cleaning kit consisting of a flexible wand and an air-filled container which applies the product directly to the evaporator by removing the evap temp sensor. It works very well......

I love this product an also viper foaming coil cleaner in a can, it is a lot of product but you will need to work up something to get it in there

Rick, slightly unrelated but do you have personal contact information for helping me with that W124 wiper mod with the VW 99 relay?