Rick's Free Auto Repair Advice

AC smells bad

AC smells bad vents when blower is running

If your AC smells bad, you have mold/mildew growing in the evaporator coil. Some people hang a car freshener, but that won’t get to the root of the problem. Others spray Lysol into the recycle air intake, but that doesn’t get to the problem either. You need to hit the evaporator coil and coat it with special anti-mold treatment.

What causes mold/mildew on the evaporator coil

R-134a isn’t as efficient as the older R-12 refrigerant. So car makers were forced to pack more cooling fins on evaporators on AC systems. The brainchild engineers that came up with this design was really thinking on his feet. Unfortunately, all AC evaporator coils remove humidity from the air, and that condensation wicks deep into those fins. Turn off the car and let that water sit there and pretty soon your AC smells bad because it’s growing mold.

To make matters worse, many car owners don’t change their cabin air filters on time. A clogged cabin air filter reduces airflow and that prevents the evaporator coil fins from drying off completely.

You need to kill the mold/mildew on the evaporator coil

Kool-it makes an antibacterial spray that not only knocks out the science experiment growing

Musty smell in car

Shoot evaporator cleaner disinfectant directly into the heater case to kill mold, mildew and coat the coil to prevent it from re-occurring

inside your dash, but also treats the evaporator coil to prevent it from happening again soon. The manufacturer says that one treatment lasts a full year. I have no connections with the company, but I have used their product and it works well.

How to use Kool-IT

Locate the AC condensate drain tube. It’s located at the bottom of the heater box and look like a black rubber tube. You’re going to remove it. But first, lay an old towel under it in case the drain tube is plugged. If it is, a lot of water may rush out of the drain when you remove it.

If water comes out, that means the drain tube was plugged. Once the water stops draining, clear out the drain tube using compressed air or a pipe cleaner.

Next, connect the tube from the can of Kool-IT to the drain. Press the nozzle and load the entire can into the heater box.

The product will foam up and fill all the nooks and crannies in the evaporator fins. The antibacterial cleaner will kill and clean the evaporator. Follow the directions on how long to leave it in. Reconnect the drain tube and the foam will dissipate and the crud will flow out the drain tube.

Run your AC at full blast to dry out the evaporator coil. The treatment lasts about a year.

© 2012 Rick Muscoplat

Posted on by Rick Muscoplat

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