CarTalk.com Best of Deals Car Reviews Repair Shops Cars A-Z Radio Show

Air conditioner drip?

What is the cause of moisture dripping on the floormats after the air conditioner is on a while, say an hour? Can I fix it myself?

The AC evaporator drain tube is clogged. You should be able to clear it from under the car. DO NOT crawl under a car supported only by a jack. Use ramps or jack stands. The tube is on the firewall, low on the passenger side.

The drain tube is supposed to carry the water to the outside of the car, where it drips onto the ground, but if debris such as dirt and leaves gets into the HVAC air intake it can clog the tube. Then the water drips onto the floor.

AC drain tube under engine is clogged. If you can find it, and if you can get to it, you can clear it with a coat hanger. If you can’t get to it, it will need togo on a lift.

I have heard similar questions on the radio show and it seems a blast of compressed air through the drain tube to free any blockages would be step 1. Find a friendly mechanic to do it for you.

I would not recommend a coat hanger. It can damage the drain or it can damage the evaporator unit of the A/C. Comprerssed air is the usual tool. The alternative to compressed air (be careful don’t over do it or you can blow the drain hose off) is string trimmer line from the garden store.