I have a central air conditioning unit for downstairs and a separate one for upstairs. The upstairs one is a horizontal York split-system AC/furnace system that sits in the attic. A couple of days ago, when the AC was on upstairs, I noticed some water dripping down from the ceiling. When I went up to the attic to check, I saw that the water was coming from the external drainage pan, which had a hole in it. This is a (36 x 8 1/4 x 1 1/2) galvanized tray attached to the underside of the supply duct and has a drain pipe connected to it at one end.

When I took off the pan, I saw that it was all rusted and corroded and had a couple of holes at the bottom. I thought all I had to do was replace the pan, but when I called an AC dealer/service firm, the person I talked told me that a central air unit has two drainage pans--the primary one is inside the unit and the secondary on is outside and serves mainly as a fail-safe device. He said that if the outside pan is all rusted and corroded, that means either the condensate drain inside is clogged or the primary pan is leaking. If it is the latter, the whole system has to be replaced because they don't make spare parts for the primary drain pan. He said he has seen many cases like this in systems that are 15 or 16 years old. But my system is only 10 years old! We bought the house new 10 years ago.

I don't mean to be distrustful, but I don't know much about central air conditioning units and I don't to change out the whole unit if all I need is to change the drainage pan.

Please advice. We have visitors coming in a couple of weeks to stay with us for a few days and the temperature shoots up and the AC is not working, it will be a disaster. If we have to replace the whole unit, how much are we talking about, ball-park figure, for the equipment and the labor?

 

Probably all you need to do is clear the primary drain pan. As you were told, it is inside the fan unit. It sits directly under the evaporator coil and catches the humidity as it condenses and drips off the coil. Every drain is a little different and that makes it tough for me to tell you exactly what you need to do. If you examine the fan unit you will see the drain line where it exits the pan. It will probably have plastic pipe about 1 inch in diameter connected to it. That pipe must run downhill all the way to its end. It should have a trap in it near the unit. That could be made of 90 degree elbows or it could be a formed piece of pipe. Its purpose is to hold a small amount of water to keep air from moving through the pipe. If the end of the drain goes to a location you can access, put a wet vac on it and suck all the water and sludge out of it. If it terminates in a location you can't get at, maybe you can take the cover off of the air handler by the drain fitting and get into the pan from there. It is usually a tight space to try to work but you may succeed. Possibly you could put a flexible hose on the blower side of your vac and blow water and sludge down the pipe to clear the drain. The other pipe at the panis the secondary drain and if you look closely, you will notice it is at a slightly (maybe 1/4") higher location. That drain should only get water when the primary one is blocked. I always run the secondary drain to a small bread pan and put in a float switch that stops the outdoor unit when the water starts to fill the pan. It prevents problems like yours where the secondary drain becomes the primary until it fails. All the while you have no idea there is a problem brewing. If you need more info, post back.

Ken

 

With Ken all the way here. On that over flow pan under the unit up there . Code here is the pipe from it has to run out side over a door or window. So you can see if it is over flowing. This is so, if the overflow switch dont work you will know something is wrong


ED

 

Thanks for the quick response. The insight you provide is very helpful.

 

I have an air handler in the attic with water leaking out at the bottom of one of the ends where the air duct is attaching to it.

I have taped it a couple of times with leak seal foil tape. However it is leaking again. It appears that foil looking end piece with the air duct attached to it is now leaking at another place, seems like there is water inside and it keeps moving around to a different place after taping.

Any help? Can I replace the end piece where it attaches to the air duct?

 

Dont try and tape up the outside of it. Lets find out where or why we have water running out of the blower unit first. Filters clean??blower clean coil there clean. No ice or frost on lines or coil. Drain line clean and clear water running out of it??Pan under the coil clean and clear? unit level up there. When running is the big copper line cold and wet. The small copper line warm to hot???

ED

 

Does anyone know if all central air units have a primary and secondary pan. It looks like my secondary pan is flooding with water and I can see there are two drains on my unit. The bottom pan was filled with water and was leaking from the back-up drain (i think its back up). From reading the precious posters problem, I think my primary drain (the one with the trap) for the internal pan is clogged, but I do not have a shop vac to suck out all the gunk. I have an inflatable bed pump and a leafblower I was thinking of using to blow out any crud in the drain, I am definately no plumber but I feel I can fix it if I get the right pieces. Does it sound like I have a good idea how to fix this and do you think a bed pump would be a good idea to plow out the main drain line?

 

Blowing out usually only puts the blockage back in the pan. Unless you can blow from the pan the same way the water flows. After you get it open, it might be a good idea to put some bleach in there to kill the algae. Only a couple of capfuls would be needed.

Ken

 

I rarely find much success on these forums when things go bad as its usually beyond a simple repair, but i had to give a big shout out to KEN for the suggestion to use the shop vac to try and clear the drains. We had water leaking outside the pan, seeping down into the walls, down stairs again to the first floor. we thought initially it was a bad toilet seal but ultimately heard the drip in the wall and went into the attic to find water everywhere. After a few good seconds of sucking, out came a blast or nasty, orange, corroded looking water with all sorts of orangey silt. Tried it again a few times and got three or four good gushes out of it. For now...i think the problem is solved. We'll probably have our AC service guys come out to do their annual inspection and see what they find...

THNAKS SO MUCH!! if i could post the video of the flood gates opening i would!!
Dave W
Charleston SC