What are the strange noises coming from my car’s air-conditioning system?

Let’s try to track them down
by Joey Bernardez | Mar 9, 2019
PHOTO: Pixabay

A reader has sent in this question: What could be the source of strange noises coming from my car’s air-conditioner? Limited as we are with the data provided, I’ll try my best to give you a diagnosis.

I’m assuming this sound is from within the confines of the car’s interior. Otherwise, you’d probably be asking about a sound coming from your engine bay. Since this is coming from the inside of your car and you say it’s coming from your air-conditioner, I can surmise that it’s caused by the evaporator, the evaporator housing, or the fan. These are the only parts of your air-conditioning system that are in the interior of your car. Moreover, only the fan can make a sound because it’s the only one with moving parts. This is assuming that what you’re hearing isn’t simply something that’s come loose and is rattling around.

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I think I’ve heard similar sounds before. I rode in a friend’s car a long time ago, and as he turned on the air-conditioner, it sounded like there was water sloshing around behind the dashboard. With a quizzical look on my face I asked what the sound was. He jokingly replied: “May washing machine sa likod ng dash. Naglalaba ako.” We both laughed, but I never forgot the incident and wondered about that sound. As I learned the ropes of car maintenance, I found out what was causing it.

The evaporator has an evaporator fan. That’s what blows the cool air into your cabin. That fan, combined with the water from the condensation that fails to drain out, can produce a sound much like a washing machine’s. When the water from the condensation fails to drain out of the evaporator housing and collects within the housing, it can slosh around as the water hits the fan.

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That fan can also produce a rattling sound if it becomes unbalanced. You’ve heard electric fans that have gone out of balance, right? An evaporator blower can do the same thing. Fan blades can become brittle and chip off, causing an imbalance and triggering a fan to rattle. These sounds can be avoided with preventive maintenance.

Have the air-conditioner cleaned every other year and it should be fine. This will prevent clogged drains so that water from the condensation that the air-conditioner produces can drain out. Also, make sure the fans are working.

Hope this helps. Let’s tackle the possible noises coming from the engine next time. Thanks for writing in!

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PHOTO: Pixabay
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