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lou’s garage

When my air-conditioning is on I hear a sound from the front to rear on the passenger side of my 2012 Dodge Caravan minivan with 137,000 kilometres on it. Can you offer some ideas?– Bob

Noises will travel through the chassis of any vehicle; trying to ascertain their source can prove challenging.

Have an assistant travel with you sitting in different positions within the cabin, listening and noting where the noise appears loudest.

From the drivers' seat, you are closer to the front HVAC unit and any noise emanating from it should be obvious.

Most Caravans do also have a rear HVAC unit located just above and behind the rear passenger wheel. Toggle the rear AC on and off, listening for any audible changes.

AC systems in general can emanate a variety of noises, anything from a blower motor that screeches due to a failing bearing or a flutter when debris finds its way into the fan.

An air blend door actuator changes the air flow within the cabin and can sometimes get stuck in one position. When frozen, the motor trying to open or close the blend door may do so perpetually, causing a continual clicking noise.

The air-conditioner's expansion valve changes the state of the refrigerant from a liquid to a vapour; an occasional hiss from this device is considered normal.

A defective valve or a system running low on refrigerant may result in an expansion valve that makes erratic, unusual noises.

Lou Trottier is owner-operator of All About Imports in Mississauga. Have a question about maintenance and repair? E-mail globedrive@globeandmail.com, placing "Lou's Garage" in the subject area.

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