Rick's Free Auto Repair Advice

AC smells musty

Get rid of musty smell coming from vents when blower is running

If your AC smells musty, you have mold growing in the evaporator coil. Forget about Lysol, it’s not a permanent solution. You need a special anti-mold treatment.

The cooling fins on an R-134 A/C system are tightly packed to get maximum cooling in a small heater box. The brainchild engineer that came up with this design was really thinking on his feet. Unfortunately, all that condensation wicks deep into those fins and pretty soon your AC smells musty because it’s growing mold. You can spray a can of Lysol into the fresh air intake on your car and it will help, but only for a short period. You really need to attack the problem.

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’m have no connections with the company, but their product works well.

Find the drain tube from the evaporator/heater box and remove it. If a lot of water comes out it means the drain tube is plugged and you must clear that before proceeding with the repair. Insert the tubing from the spray can of cleaner and depress the nozzle. That’ll fill the entire evaporator with foaming antibacterial cleaner. 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.

A clogged evaporator drain can make the problem even worse. If the mold gets bad enough, the slime clogs the drain hole and turns the whole evaporator box into a swimming pool of toxic sludge. So make sure you snake out the evaporator drain before attacking the rest of the mold problem. Run your A/C. If you don’t see a puddle of water under your vehicle, you’ve got a plugged drain. Use a pipe cleaner to clear it. Then inject some clean water to flush it out. You might be tempted to add some bleach to the flush water, but don’t do it! Bleach is very corrosive to the metals in the evaporator.

© 2012 Rick Muscoplat

Posted on by Rick Muscoplat

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