How To Unclog Air Conditioner Drain
A couple months ago I detailed the travels of Harold the Helicopter’s journey to the bottom of our guest bathroom toilet, and the subsequent DIY plumbing project I undertook to rescue him. It wasn’t exactly a fun project, but I did learn more than I ever wanted to know about the anatomy of a residential commode, and I saved a ton of money I would have had to find a plumber for the effort. When a suspicious drip formed above our back door I knew it was again time to channel my “Tim the Toolman” skills and get to the bottom of it, without searching Angie’s List for an air conditioner repairman. I soon found myself in the attic staring at a nearly-overflowing air conditioner drain pan.
Gain Some Altitude
I suspected a problem with the air conditioner drain since when the drip started it had not rained in a few days. I checked the main air conditioner drain pipe which comes out of the side or our home and noticed it was draining, but not with as much volume as it typically did. In fact, a small puddle had formed in the past and I added a piece of 1″ PVC pipe to extend the drain away from our foundation. I accessed our attic via the garage and found the air conditioner’s main evaporator unit. The pan underneath the unit was nearly full of water, which I knew was a problem. The source of the drip was a secondary drain pipe connected near the top of the pan and running to the back of our house with an exit just above our back door. I was thankful the builder and air conditioner installer put the secondary drain’s exit in a high-visibility spot so homeowners would know there was a problem.
Shop Vac to the Rescue!
I’d been wanting to pick up a small, inexpensive wet/dry vac for small garage spills, and fortunately a local home improvement store had one on sale. I picked up a Stinger-Vac (just a mini Shop Vac) for under $30 and returned home to put it to use. Lucky for me, the Stinger’s hose attached perfectly to the 1″ PVC drain pipe and began to immediately suck out water and sludge that had accumulated inside the pipe. As it filled I simply dumped the water in our yard, reattached the vacuum and started it up again. After a few cycles I assumed I had made a dent in the amount of water from the pan and returned to the attic to view my progress. This time I carried a container of household bleach with me.
Preventive Maintenance
If I had taken this step earlier in the spring I could have probably avoided this near-disaster, but better late than never. I accessed the air conditioner’s drain by removing a PVC cap on the top of drain pipe by hand. If the pipe was properly installed, this cap should only be tightened by hand and can easily be removed and replaced without any tools. I added a little bleach to the drain pipe to clear away any accumulated algae and mildew. Going forward, I will make this part of my checklist to prepare our home for summer.
My total material costs for the project was $32.09 for the Stinger Shop Vac. We had bleach on hand so I didn’t factor this into the cost. The whole process of unclogging the air conditioner drain took about an hour, and saved me from having to make a $50 service call to our air conditioner repairman. For a net savings of roughly $20 I am now the proud owner of a mini shop vac.
If all attempts to unclog the drain fail, it may be necessary to contact a plumber or air conditioner service professional. I recommend checking out Angie’s List to find reviews of service professionals in your area.
Great job! My husband is um…not so handy, but he is brilliant on the computer. We instead befriend handy people and I offer food in exchange for services. I am a crazy lady in the kitchen and I pick people who have wives that don’t cook
Total win-win situation 
@Amy: Way to put those culinary skills to use! Actually, I didn’t use to be so handy either. When we moved to a new town I didn’t have any “handy” friends around to bribe into helping me, so I had to start figuring things out, or start forking over megabucks for repairs. Well, you know me so you can imagine the direction I went!
My husband of 37 years has always been extremely handy, changing the oil on the cars and doing all car repairs, fixing the washing machine & the dryer, which are over 30 years old and running fine. It’s a great way to save money also a lot of personal satisfaction in a job well done.
@Sally: Indeed it does provide satisfaction. I rarely get a chance to get my hands dirty in my full time job, so I enjoy taking on challenges around the house! Some might accuse me of finding things to “fix” on occasion – you know, the whole “sometimes firefighters are arsonists” deal!
The last project I tackled was putting in grout after our ‘professional’ tiler/handyman forgot to do it. Before that I repainted the living room and will probably tackle the stairs this summer. I’ve also re-caulked and weatherstripped the windows. Like Amy, my husband is stellar on the computer, no so much with other stuff.
Our recent projects (my wife usually helps out) have included repainting the entire inside of our house (it was a hideous pale pepto-bismol pink when we moved in <shudder); installing replacement flush and fill valves in the toilets, and swapping out the guts but not the shell of the fan in one bathroom. We probably saved several hundred dollars over the last year doing this sort of thing ourselves. Next up, re-sealing the shower stall in the guest bath (poorly done by the prior owner and now peeling from the walls).
I and several friends of mine have a handyman circle. We all tired of paying such high fees to plumbers, electricians, and the like several years ago. However, some projects, such as any plumbing that involves copper pipe, require specialized skill and tools that are often not as cheap as $30. When one of us learns that skill, we become the trainer for the next project that requires it; once any of us has purchased a tool, we all know it has been purchased and now have it in the common pool of tools we have available. Worth doing with your neighbors, I believe!
Our a/c unit began backing up into the house. We used our bissell steam carpet cleaner to suck out the drain. We used a wire hanger to clear it out and sucked away.
We were elated that we were able to figure out the problem.
We plan on suctioning twice a year from now on.
Great post.
I had the exact same problem last summer, but my clog was in the attic as the drain from the A/C runs into a vent pipe. I wish I had thought of using a shop vac! I ended up using a piece of tubing to siphon the water out of the pan and then removed the horizontal run of PVC to clean it out. Thanks for the tip @ the shop vac and reminding me I need to put some bleach in the drain pipe.
Very impressive! Just a pointer for you (since I have worked for my family a/c company since I was about 10)…the unit it the attic is not the condensing coil, but rather the evaporator coil. The condensing coil is the large one outside.
One more thing…it is ok drain run off to be close to your foundation, in fact it is good for it. It will help prevent foundation cracking.
Another reason the drain can clog up is that the main house plumbing can be clogged also (depending on how it was installed) and that can be as easy as cramming salt, baking soda and vinegar into the bathroom sink attached to the main drain and flushing the line out like that.
@Jane4girls: I’ve made the correction in my copy above to correctly identify the “evaporator” coil – thank you for keeping me straight!
Great post. I love hearing about DIY projects. And I love the pictures.
Not sure this counts as a DIY project, but lately I’ve been darning my socks and fixing other clothing items that need repair. I think I’m addicted now though. I keep looking around for other things to fix. LOL
Be sure to install a float switch in that pan below the evaporator so that if the drain clogs, overflowing into the pan, the float switch shuts off the compressor before the pan fills and overflows onto your ceiling.
In my case, the evaporator was in the basement next to the water heater.
When the drain clogged and pudled water on the conrete floor, I thought the water heater was leaking, and so paid to have it replaced!
Carnival Of Tips – June 7, 2008…
Welcome to the June 7, 2008 edition of Carnival of Tips. We had over 60 great entries this week on:
Business & Career:
Mark Riffey presents The fine line between personal and business posted at Business is Personal.
Raymond presents Work From H…
… A cup or two of Clorox/bleach down the air-conditioner condensation drain-pipe is the best cure & preventative for clogs.
Here in Florida those A/C PVC drain pipes clog regularly; there’s some type of clear fungus/mold (…looks like a jellyfish blob) that grows easily in those wet, warm & dark pipes.
Copper A/C drain pipes (more common in northern states) are toxic to that growth… so it’s not usually a problem up there.
But lots of contractors install the PVC drain-pipes without an access port to dump in the Clorox. You have to add your own PVC T-Connector & port … not a difficult task.
Those ‘Float Switches’ that kill the A/C power when the drain-pipe clogs… are generally a bad idea, unless your Air-Handler unit is in the attic where a moderate water leak could do expensive damage. Losing A/C in Florida is much worse than a little water backup on the ground-floor/garage.
[...] to install a programmable thermostat, but have been a little intimidated by the thought of any DIY project that involves wires. What can I say, I’m a chicken when it comes to anything electrical. [...]
i need to get one of those mini shop vacs! what I do IS take the garden hose and fit it to the pipe outside and run it into the pipe and it has helped – the sludge loosens up and runs out….slowly sometimes….I think the shop vac might work better…but the hose works too…..(you might have to do it a few times during the season….I am alone here in FLA and its terrible when I see the water on my laundry room floor! I always think it might be the washer or water tank…but its always ( so far) the clogged A/C …Now I am going to pour some bleach in there….now does anyone know how I can fix the door handle that fell off of my sliding doors?? HELP!! the screws are stripped. I hired someone a few weeks ago to fix it and now its worse…..I will have to figure it out myself and save some $$
Thank you so much for this post. We had a clog in our air conditioner drain and were unsure how to proceed. After my husband had poked around to no avail, we were about to call our plumber, but I decided to make a quick search on the internet. I found your post and my husband followed your advice. You really don’t want to know what came out of our drain. Now, the clog is gone and my husband is so happy he didn’t have to call anyone. Again, thanks.
you put bleach in your AC system?
@jauques: Not in the system itself, rather in the line draining from the catch pan to the outside of our house.
Thank you for your post. We just used our shopvac to get the water/sludge out of the pipe and then poured hot water and about two cups of bleach down the drainage pipe. Thanks for saving us some money on the repair man and for saving me from using up all my towels every day!
@Thankful Central Floridian: So glad you found the post and it helped! I looked around for help when I ran into trouble and couldn’t find much. Fortunately, my AC guy was willing to talk me through it on the phone without coming out for a repair charge. I decided to pass the info along to others to hopefully save them some money, too.
Ok, I have tried shop vac and putting bleach down drain and have not been able to keep from ac draining into secondary drain. Do I just keep doing it or is it time to call someone. Our drain flows into bathroom downstair sink. That is where I have been trying to suck out drain. I can look down pvc pipe and tell water is backed up. Any ideas?
@18option: If you have a plumber’s snake you may try running it down the drain to remove any large blockages. You might also want to use the wet/dry van to vacuum out what is standing in the pan to return the water level below the mark where it runs to the secondary line.
If you still don’t have any luck you may need to contact your AC service provider, as the drain could be clogged at the connection to the overflow, or it might be a more serious clog. Good luck!
I have a central Florida AC unit too and I was told just today by an AC company that owners should flush the condensate line with warm to hot water and vinegar every month!
After reading several posts online I see that it is important and I partially drained the line.
There seems to be some disagreement about the use of bleach in PVC though.
Any thoughts?
BeDammit
@BeDammit: I have since discovered some of the same concerns with bleach. Vinegar is probably better for your environment, depending on where the line drains out. For instance, ours spits out into the yard where I’d rather splash a little vinegar. Good suggestion!
Re: How To Unclog Air Conditioner Drain
I thought the water on our garage floor was from the car a/c until I realized otherwise!!
This was a great tip, THANK YOU !!
I would add that I have a Ridgid shop vac with a 2 1/4 nozzle, so I fashioned an “adapter” out of a Sam’s Club drinking water bottle (the hour glass shape). I cut the bottom off the bottle and found this was a snug fit on the shop vac, with the cap end of the bottle being an equally snug fit in the drain pipe PLUS I had the added advantage of being able to SEE exactly what was being sucked out of the drain line.
Thanks again.
My father-in-law has a secondary drain ( air conditioner) that drips a lot of water onto his backyard lawn. He likes to catch it in a bucket to use to hand water his plants. My question is this…
Can my dog get sick from drinking this water? Is this water contaminated?
Sincerely,
Linda
@Linda: I’m not sure about the possible contaminants in the water, but it’s possible the water is not safe as it may have various components of the air conditioning system in it – freon, pipe debris, rust from the pan, etc.
My drain is clogged as well, however the primary drain goes to a bathroom sink, and the secondary drain (where water is now dripping out) sticks out of the roof on the second floor. Any idea on how to unclog a primary drain that goes to a sink?
Last night my husband and I noticed our AC wasn’t working as it normally does do I suggested changing the filter. It was absolutely filthy, but what made us more upset was the fact it was soaking wet. We turned off the AC and I did a little research on why water would be dripping and we figured it was the drain pipe (even though I regularly put bleach in at the T – actually did it on 6/10/09 same as the last filter change). Anyway, my husband and I set off into the night with a flashlight looking for the exterior drain and we couldn’t find it. there are no exterior drains coming from our home besides the one for the hot water heater relief valve. We decided to do the shop vac at the T to see if that would help. We ended up with approx 2-3 gallons of water and trash. Should we be concerned that we are unable to locate the exterior drain? Or should we just continue to use the vac at the t pipe inside if this happens in the future?
@Rebecca: While it’s good you were able to put the shopvac on the “T,” I worry that you may be pulling any blockages back up the line. If you can’t locate any exterior drains check around bathroom sinks – builders have been known to drop them there (see a couple examples in comments above). It might be possible to loosen/detach the AC drain line from the primary sink drain and shopvac from there. Bleach or vinegar with a warm water flush should help as well.
Great tip! I’m renting and i just noticed that my lease says I’m responsible for dealing with A/C drain line clogs! I about freaked out until I found your post.
Now, mine’s a little tricky. The system is old, and the drain pipe is PVC and comes out of the unit (in the garage), then disappears down into the slab. The whole system is sealed and glued (I assume by pvc glue), so there’s nowhere I can access the line to try sucking anything out. Should I cut into the PVC pipe and try to suck/snake it out? Just had a baby and it’s August in central FL so AC is pretty important. Thanks!
Tom in WP – Mine goes straight into the floor too, but I do have an access port for pouring bleach in. My husband and I looked at every other drain in the house, even behind the bathtub, and the drain pipe doesn’t connect to any of them. we believe it has it’s own drain. I unclogged ours the other night by pouring about 1/2 cup of baking soda followed by 2 cups of vinegar into the T pipe (after I used the shop vac on it). I can’t remember the website I got that tip from, it may have been this one, either way, it worked perfectly!!! It might be a good idea, if you are going to have to cut into the PVC anyway to add on an access port for bleach or baking soda and vinegar so you won’t have this happen again…if you are planning on staying in the same house for a while. Good luck.
FIXED – Sorta…
Tried shop vac sucking and blowing on any and all available pipes exiting the house – no dice.
Then, escalating the destruction, I drilled a good-size hole in a high point on the drain pipe near it’s exit from the AC unit. I figured if I was going to wind up cutting the pipe off, this couldn’t hurt. No water came out, so I stuck the curly-q end of an undone wire clothes hanger down the hole – it came out wet and covered in goobies. So I bent a 90deg bend in the other end of the wire hanger, shoved it into my drill, worked the rest of the wire hanger down into the hole, and commenced to give the begoobied pipe a good internal scrubbing. poured some water down in the drain pan, and it drained right out – success!
I did pour some chlorox in there too, and will add some more later, along with some hot water and vinegar and baking soda.
$0 total out-of-pocket expense so far. Thanks for all the help!
@TominWP: Nice job! Hope the fix holds up so you can avoid paying for any repairs.
I found water dripping from both the pipes outside our house and the one upper on our front door. Any one here have an idea why this happened? I have tried the tips suggested here before and it worked but not this time. Any suggestion will be greatly appreciated.
Binxz
I have had continuing problems with our AC units in the attic draining through the same drain as the upstairs sink. I was putting algaecide down there once a month, forgot last month and it backed up into her sink. I am guessing there is a trap below her sink on the first floor that is getting clogged? I have a snake I run down there and it clears the clog. I like the baking soda and vinegar idea, this creates a foaming? How often do I need to do this? Our AC runs almost year round in Houston.
Here is a story.
My Inverter Air conditioner has 2 drains out that drain to a downpipe connected to the guttering. Well the downpipe got clogged and the water went up the drain pipes of the air-con into the unit and leaked all over the floor in the house.
After removing the drain pipe from the down pipe (to stop the flood inside the house) I am scared to even start the air-con in case its electrics have been damaged.
I wonder if the water that went inside it will just drain out again.
I plan to let it dry out for a month. And then turn it on.
I wonder if I can claim on insurance if it doesn’t work anymore.