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Q: Gross smell from the AC

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Every morning when I turn on the air conditioning in my 2011 Camry LX(62k miles), it smells musty. It takes about 5 minutes to go away, but it comes back every morning. The dealer sprayed a chemical in the AC unit, and it worked temporarily, and then after two weeks, the issue came right back. I want to make sure I'm not breathing something unhealthy. What could it be?

It sounds to me like the drain for the A/C system is clogged. When you run the vehicle’s air conditioner, condensation forms on the evaporator, just as it forms on a glass of ice water. The A/C drain allows the condensation to exit the vehicle, but sometimes debris gets caught inside of it and blocks the passage. When this happens water gets caught inside the evaporator box and over time that musty smell starts to form. If this problem is left untreated water can escape the evaporator box and drain on to the floorboards of the vehicle, saturating the carpet and floor mats. I would definitely recommend having a professional inspect the A/C drain for any debris blocking the passage and inspect the floorboards for any dampness. Toyota has a technical service bulletin that also offers to install an insect repellent tip for the A/C drain hose to keep environmental conditions from re-occurring. If the concern can be tackled early on, it may be as simple as unclogging the drain and removing any excess water. If the carpets are damp, a wet/dry vacuum can be used to remove most of the water and you can place black and white newspaper between the carpet and the floor mats for a day or two to help absorb any moisture that couldn’t be removed with the vacuum. If the smell remains after these procedures have been made, the carpets may need to be removed and inspected for mildew and mold.

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