# a/c overflow question



## daddyhoney (Dec 4, 2006)

My a/c unit is dumping condensation into the overflow pan and out the discharge tube instead of down the regular sewer vent pipe. I tried to blow out the line with an air compressor but nothing changed. What should I try next aside from calling the a/c company? Thanks, Gary


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## SV_DuckBuster (Sep 18, 2007)

When you blew out the line, did you block the main discharge hole in the condenser? If not, you probably just blew air back into the condenser and not down the drain line. 

You may have to pull the panel on the condenser in the attic and block the main discharge hole. Then blow air again to unblock the main line. Once the clog comes loose, pour a little bleach down the drain line every now and then to keep it from clogging up again.

PS. I cut my 3/4 pvc main drain line and installed a valve between the condenser and the vent so that I can close off the valve and blow out the line. Then open the valve again and all is good. Prevents from having to pull the panel and re-seal it afterwards.


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## carryyourbooks (Feb 13, 2009)

^^^what buster said, plus try using a shop vac to suck out the blockage.


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## fishingcacher (Mar 29, 2008)

carryyourbooks said:


> ^^^what buster said, plus try using a shop vac to suck out the blockage.


That's what I have to do. Just use a rag around the wet dry vac hose to get a good seal on the pipe.


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## tinman (Apr 13, 2005)

*condenser*



SV_DuckBuster said:


> When you blew out the line, did you block the main discharge hole in the condenser? If not, you probably just blew air back into the condenser and not down the drain line.
> 
> You may have to pull the panel on the condenser in the attic and block the main discharge hole. Then blow air again to unblock the main line. Once the clog comes loose, pour a little bleach down the drain line every now and then to keep it from clogging up again.
> 
> PS. I cut my 3/4 pvc main drain line and installed a valve between the condenser and the vent so that I can close off the valve and blow out the line. Then open the valve again and all is good. Prevents from having to pull the panel and re-seal it afterwards.


Not picking on you DB, but don't you mean evaporator instead of condenser? The condenser is the outside unit, or at least it has been for the last 47 years that I have been playing with them.

Tinman


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## GT11 (Jan 1, 2013)

My unit has a little riser pipe on the drain. Last time it did what yours is doing, I poured a little bleach in the riser and cleared itself in a matter of minutes. It is typically algae buildup.


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## SV_DuckBuster (Sep 18, 2007)

tinman said:


> Not picking on you DB, but don't you mean evaporator instead of condenser? The condenser is the outside unit, or at least it has been for the last 47 years that I have been playing with them.
> 
> Tinman


Yes, typing too fast. Evaporator.


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## carryyourbooks (Feb 13, 2009)

fishingcacher said:


> That's what I have to do. Just use a rag around the wet dry vac hose to get a good seal on the pipe.


i use a 20 oz coke bottle, too, cut in 1/2 and duct taped to make a good seal.


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## fishingcacher (Mar 29, 2008)

carryyourbooks said:


> i use a 20 oz coke bottle, too, cut in 1/2 and duct taped to make a good seal.


Interesting idea. Once I hear and feel a thud into the wet-dry vac I am good to go.


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## kneekap (Nov 13, 2012)

Once you get the line to the sewer cleared, the AC guy told me to use some of those blue tablets in the bottom of the coil area to keep the algae down.


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## mike1215 (Jul 16, 2013)

Just run a snake down the main drain line.


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## Coon (Jul 18, 2006)

Check out these products available from local manufacturer Rectorseal...condensate control switches, drain line pump, drain pan tablets and more...

http://www.rectorseal.com/index.php/hvac/


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## HarryK (Jun 5, 2008)

I have same setup with little riser pipe, but my actual drip pan is bone dry and the pipe sending the condensate(seperate from my drip pan piping) away is causing my 2nd floor lavatory sink to back up which tells me that it is clogged in between my 1st and 2nd floor and my A/C unit is in my attic (3rd floor)..am I correct? Why would they plumb it to my lav and not my tub drain...? Also, the drain pipe in the wall is at least 2"...how does that get clogged. It just started backing up couple of days ago and I tried plunging sink to no avail. Will sending bleach solution down my riser pipe do the trick? I am bailing water at a fast rate and afraid that if Im not home it will overflow.


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## Mantaray (Aug 29, 2004)

Try to read through this thread to see if your problem is similar to the one I had years ago. Mont's suggestion helped. I've never had the same issue again but guess I should have kept an eye on it. Good luck!

http://2coolfishing.com/ttmbforum/showthread.php?t=229402


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## mustangeric (May 22, 2010)

HarryK said:


> I have same setup with little riser pipe, but my actual drip pan is bone dry and the pipe sending the condensate(seperate from my drip pan piping) away is causing my 2nd floor lavatory sink to back up which tells me that it is clogged in between my 1st and 2nd floor and my A/C unit is in my attic (3rd floor)..am I correct? Why would they plumb it to my lav and not my tub drain...? Also, the drain pipe in the wall is at least 2"...how does that get clogged. It just started backing up couple of days ago and I tried plunging sink to no avail. Will sending bleach solution down my riser pipe do the trick? I am bailing water at a fast rate and afraid that if Im not home it will overflow.


you need to run a snake through line. give me a shout if you need some advice or help. WWW.yourhoustonplumber.com 832-475-4700


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## Tuff (Nov 29, 2011)

when you get it clear the best thing to do is introduce some chlorine into the system. pouring bleach every so often works, but is a PITA (not to mention the stuff you gotta do to unclog the line if you forget). many years ago it was recommended to find a friend that had a swimming pool that used big chlorine tablets (hockey puck size/shape). one of those tablets/pucks always manages to break in the bucket-put a big chunk in the pan. problem solved.


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