Car Doctor Q&A: Rinse and Repeat

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This week, AAA’s Car Doctor John Paul diagnoses a heating and air conditioning issue that only crops up after the car goes through the car wash.

Q. I have a weird problem: the heat and air conditioner in my car works great until I go to the car wash. After I go to the car wash the heater fan — even on high — has very little air blowing through the vents. After a couple of days the blower fan goes back to normal.

Do you have any idea what is going on?

A. If your car has a cabin air filter it is possible that the filter is getting wet/soapy and blocking the air flow of the filter. Next time this happens take out the filter and see if it’s wet.

Replacing a cabin air filter is easy. We’re not sure of the model of your car, but it’s easy enough to find a video by searching YouTube. Here’s a more general video from Advance Auto Parts:

It may not indicate that anything is wrong. What could be happening is that the climate control is actually sucking suds into the climate control air intake during washing and eventually clogging the cabin filter.

Next time you wash your car or go through a car wash, set the climate control to the recirculate (recirc) mode and keep the air conditioner shut off. This may solve the problem.

John Paul is public affairs manager for AAA Southern New England. A certified mechanic, Paul tests dozens of new cars each year and also hosts a radio show on AM 950 and 550.