I need help figuring out what my AC is doing

EddieWalker · Aug 22, 2017

I have a ten year old American Standard AC system with the filter at the bottom and the return air coming in below the filter. I do not have a pan. It sits off to the side of my garage. Over the last couple of months, it's periodically flooded the floor with water. I've tried cleaning the coil, and removing all the crud from the V shaped tray under the radiator looking thing that drips water into the tray. From the tray, there is a 3/4 pvc drain line that goes into a 4 inch sewage line that goes into my septic tank. The slope of the drain line is fairly steep, so water should flow through it quickly. I add a shot of bleach to it every month when I change the filter.

I cut the drain line, unscrewed it and put a section of flashing under the hole to drain the water. I wanted to see if I could get it to flow without restriction and allow my floor to dry out. It helped for awhile, but then the water stops flowing and I'm flooding again. The filter is soaked. The water is everywhere.

I took of the front panel and the water is less then halfway up the V shaped plastic trough looking thing that catches all the water.

While watching the water through the opening, I can see it dancing around in there. I can stick my finger into there and it gets wet with just a small amount of water coming out, but that's just temporary. To me, it seems like the fan is pulling the water up and out of the V shaped trough and spreading it all over the place. After ten years of no problems, why would this start this year and how do I fix it?

I do have a great AC guy who I will call to come out if I have to, but I would really like to be able to do this myself. Just to understand what is happening would be great!!!!

Sheldon Hamblin · Aug 22, 2017

It sounds like there is a hole somewhere in your collection point. With mine it was a pan. Yours may be in the V trough.

wthompson · Aug 22, 2017

It should have a pvc trap similar to what is used on a sink drain which lets the water flow while the fan is on. or is the plastic pan is cracked?

coolreinfarm · Aug 22, 2017

Your problem as I read it is there is a high negative pressure in the return, it could be the return grills in the house are clogged with dirt or the evaporator coil is not as clean as it should be. Just because the coil looks clean on the surface it could be clogged between the the tubes inside. If a flashlight or a drop light is put under the coil and very little light is visible on the other side then the coil is dirty and possibly causing your problem. Since this is in your garage, and your able to contain water you could hose out the coil, or get your HVAC buddy to remove the coil and clean it
outside. One word of caution about the existing drain line, it should never be connected to a septic line even if there is a trap, when the A/C is not in use the small 3/4 trap will dry out and sewer gas will migrate into the ductwork. Good luck

Redlands Okie · Aug 22, 2017

Has little to do with your problem but the bleach you pour in for cleaning or other cleaners that run down the pan and into the septic tank is hard on the enzymes and septic tank health

EddieWalker · Aug 23, 2017

coolreinfarm said:
Your problem as I read it is there is a high negative pressure in the return, it could be the return grills in the house are clogged with dirt or the evaporator coil is not as clean as it should be. Just because the coil looks clean on the surface it could be clogged between the the tubes inside. If a flashlight or a drop light is put under the coil and very little light is visible on the other side then the coil is dirty and possibly causing your problem. Since this is in your garage, and your able to contain water you could hose out the coil, or get your HVAC buddy to remove the coil and clean it
outside. One word of caution about the existing drain line, it should never be connected to a septic line even if there is a trap, when the A/C is not in use the small 3/4 trap will dry out and sewer gas will migrate into the ductwork. Good luck

This makes sense. I'll take a look at it and see if I can clean it.

Thank you!!

topbuilder · Aug 23, 2017

"it should never be connected to a septic line even if there is a trap, when the A/C is not in use the small 3/4 trap will dry out"

True. The common fix for this problem is to tie into a sink drain after the P-trap.

EddieWalker · Aug 23, 2017

The PVC is new. I replaced it thinking that might be the problem. Even without it attached, water does not come out of the drain hole. You can see it inside there dancing up and down, like a giant vacuum is sucking it up and out of the V shaped tray. The tray is thick plastic and does not appear to have a leak. Water is in it , but it's not draining out of it through the drain hole when the fan is running. I turn off the power and the water drains right out. The fan seems to be too powerful all of a sudden and sucking the water up and out of the tray.

Here in Texas, the AC runs for ten months. Then I have a fire to keep warm for the two months of winter. I've never smelled anything related to the septic tank come out of the AC, and I have trouble believing that the water in the trap will dry out when the temps never get out of the 50's for the two months of winter.

Egon · Aug 23, 2017

Where does the fan get it's air from?

coolreinfarm · Aug 23, 2017

You have to have a deep trap on the condensate line when the coil is before the fan, that prevents air being sucked back through the drain line, without it no water will drain. Seems that the negative pressure has increased past what the trap can hold. Check everything in the return air side of the system including the evap coil.