I recently purchased a 2012 Honda Civic (~36,000 miles). The AC will intermittently give off a paint thinner or magic marker smell. From what I understand, antifreeze has a sweet smell, and mold or mildew has a musty smell. It does not seem to be either of these smells; magic marker is probably the best description.

I am not entirely sure, but I suspect that this odor is emitted when the AC is recirculating the air. Also, I believe I am hearing a decompressing sound before I get a whiff of the odor, and it usually ends shortly thereafter.

I am just wondering if I am inhaling something unhealthy and if there might be a mechanical issue?

Here is a list of questions I have found from other people who seem to be experiencing the same issue:

Similar "magic marker" description

Describes it as "paint thinner" smell

Any insight would be appreciated.

  • I had a similar problem with a chemical, paint-thinner smell in a car. It turned out that someone at the dealership had left a bottle of tar remover in the car that only dripped when the car moved, producing a smell that came and went.
    – barbecue
    Sep 6 '15 at 21:47
  • I had a problem similar to that once myself - somebody had left a can of spray paint under a seat, and it somehow nestled itself into a position where if a passenger shifted their weight just so, the button on the can was pressed just enough to release a little shot of propellant. It hissed for a moment, then the car smelled like spray-paint propellant for a while. Sep 7 '15 at 14:23

Two things come to mind. Refrigerant or A/C system lubricant oil. They leak out together, there could be a hissing sound while the leak is in progress. Intermittent leaks in the A/C condenser area not common on newer vehicles. If this is a leak, the system will eventually quit working when the gas all leaks out.

Smells are subjective, I would not describe R134a refrigerant as "magic marker" but it does have a distinctive chemical odor.

The oil is not good for humans. The refrigerant gas is claimed to be non-toxic.


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