I have a unit that is installed in the attic and is about 10 years old. My problem is I normally have to go up and empty the drain pan every month or so, but lately it's been every 3 days.

I have cleaned out the drain pipe, poured bleach in it and still no luck. I have checked the outside drain and nothing. It seems to be just draining in the overflow pan under the unit which is a pain because it fills up and hits the overflow switch then I'm back up in the attic with the old ShopVac.

What is my next step? I really don't want to call a repair guy cause of the cost but I am stumped at this point.

3 Answers 3


Take your shop vac outside and hook it up to the drain line to suck out whatever gunk is in the drain line. If that doesn't work, you can also use an air compressor at the air handler end of the drain line to push out the clog. Or get a helper and do both at the same time.

Once it's running clean, you'll want to flush out the drain line with some bleach. Mix a 1/4 cup of bleach in to 2 liters or a gallon of water, turn off the air handler, and pour the bleach water in to the drain. Let it sit for 15 minutes or so, and pour fresh water in to flush out the bleach.


Sounds like the drain line is clogged with mold and mildew. You can have an AC repairman use a 'snake' to clean it out for a small fee (compared to major repair work). It should be done every 2 years at most.

Also, check the pipe outside to make sure it is pointed down. Lizards and other tiny critters might get inside and get stuck but not likely. It the repairman offers to insert a screen filter where the water drips out I would take the offer. It will prevent critters getting into the drain pipe that might get stuck and clog the pipe.

The screen is removed each time the drain pipe is cleaned out. It can be a messy job, and dangerous to the air-handler if you do it yourself, so best to let a repairman do it.


If your system is anything like mine, that pan is actually the secondary drain. The primary drain goes directly from the unit to the outside. In mine the outside primary is on the bottom of the wall and the secondary, which drains the pan, is on the top. I think they put it on the top so that the homeowner knows it's being used.
Rather than guessing, you may want to call in a professional, as @Sparky256 says.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.