AC drain line maintenance

Bleach kills organic stuff, does nothing about mineral scale and dirt deposits though. Vinegar can help some but it's slow. I had a similar issue a few weeks ago, started seeing water bubble from a seam in the condensate pan under the evap coil. I had to use my shopvac to dislodge the crud that had built up, looked like dirty sand, then flush with 30% vinegar, then use an adapter off my air compressor to make sure the line was blasted clear. The shopvac method is pretty safe, an adapter is about $15 or you could just tape a piece of hose or pvc up.

Do yourself a favor and make sure your drain line has a slight downward slope to wherever it drains and, if you really want to fix it, reroute to the shortest possible place to drain. Mine drains to a garage sink 6in vent only about 5 feet away.

I adopted this method after my drain line plugged solid 15 years ago:

Every two months, 1 teaspoon chlorine granules (made for spas/hot tubs) into trap, flush with water, then 1/4 teaspoon granules in trap.

I also added a Rectorseal drain trap with a high level switch; shuts down the a/c before the drain pain starts to fill up.

I use a couple cups of vinegar monthly during the cooling season (March-Nov) poured into the vent tube. I started using the industrial strength vingear (49% acetic acid vs household vingear, 5% this past year, buy at Home Depot)

But when I have had a blockage in the past, I will use bleach, and the bleach has cleared the stoppage. But that procedure maintains the condensate line downstream of the vent tube. I’ve been fortunate enough though not to have a blockage between the cased primary drain pan beneath the evaporator coil and the vent tube.

The best to way maintain the entire condensate line is to use the enzymatic “anti-slime” tablets placed the primary drain pan twice a year. What’s HVAC techs do with annual or semi annual maintenance plans. You have to remove the cased evaporator coil cover to do this, usually not that big of a deal particularly if it’s every accessible and you have a large attic (assuming it’s not in a closet), but a little more work/time than pouring vinegar down the vent tube. Often time the cover is taped along the seams (mine is) to prevent cool air leakage, so you need to remove screws & tape, and then re-tape with proper HVAC tape (not regular duct tape).

This a good anti-slime tablet used by HVAC techs



I have given though to installing a IFlow unit (it’s an easy DYI). Reviews are pretty good, it seems to be the most convenient product if it works as advertised.

IFlo Automated HVAC Drain Line Cleaning System

Easy DYI install (check YouTube) and really not that expensive. I’d prefer to install the Pro model which is powered from the air handler/furnace control board as opposed to batteries.

Bleach, espically routinely using bleach will greatly reduce the life of the coils. Hot water out of the tap twice a year. If it gets clogged use a shop vac first, suck it out both ways then if still necessary blow it out.

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What is a good schedule? Monthly?

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Vinegar once a month; about a cup will do. I also pour a cup down the washer drain line.

Fumes. Chlorine gas will attack aluminum.

Also why you shouldn’t use bleach to clean your outside coils.

I clean my coffee pot with 50/50 water and distilled regular strength vinegar every 2 months. I pour the 50/50 down my drain line after.

2 cups of 50% vinegar (get on Amazon or Home Depot) a couple times a year. HVAC guy said it's way safer than bleach, which can damage things. I don't even flush it.

Stuff is potent. I'll put it in the bleach, fabric softener, and detergent trays of the washer and an Affresh in the bin, and run a cleaning cycle and It's like brand new.

Great to put in the fabric softener tray for mildewey smelling clothes/towels too. Knocks it out.