Central Air Question

[MuleShack]

The last few days our air conditioner coil in the furnace started dropping water from the inside.

The drain tube coming out of the plenum seems to be working. Once the air is on for a while and the furnace fan runs water comes out into the lower section of the furnace and runs on the floor.

I'm guessing the coil is frosting up and then de-thawing when the fan comes on and melts it. Only way that water can be getting in there. The duct is not condensating so it has to be the coil.

The outside unit is clear of dust and debris and is blowing mildly warm air, nothing serious.

Just wondering what the problem would? Could be low on freon in the unit?

I didn't take the duct cover off to look at the coil but I suppose there could be some obstruction blocking the drain port where it goes out to the hose.

The unit is 8 years old. I believe it is a Rheem and a 2 ton?

[Whoaru99]

I'm thinking something along the lines of partially obstructed drain or maybe leak in the drain pan. Afaik, if it's freezing up then thawing out it still shouldn't leak out elsewhere unless the former is the case.

Sure, low freon can/will cause the evaporator to freeze up but, again, I don't think that in and of itself will cause the water leakage.

Usually you can tell if it's freezing if it starts blowing cold air shortly after you first turn it on, but then after a while of operation the volume of air coming out of the ducts decreases as ice blocks air trying to get though the evaporator. When mine was freezing it would get to the point where almost no air was coming out of the ducts. The fan wouldn't thaw it unless you shut off the condenser/compressor to stop the freezing and ran just the blower but it didn't leak out other than the drain.

Once you get inside the evaporator you might be surprised with a layer of "stuff" in the inlet side of the evaporator and some has fallen off, partially obstructing the drain. Buildup on the evaporator can also contribute to freeze up. Or, maybe find the pan is leaking.

[Macgyver55]

Sounds like the drip pan under the evaporator has a leak, or as previously stated the drain may be obstructed and the water is overflowing the pan.

Its not all that uncommon for the drip pan to rust or crack and develop a leak.

[mikey1685]

Check drain hose pour water down it with a funnel make sure its draining, carefully unscrew the fitting at the plenum that the drain hose connects to.They plug up there a lot. check furnace filter a dirty filter can cause a-coil to ice up, otherwise if its still icing up most likely low on freon. a iced up coil will result in a water leak ., it is possible the pan also has a hole in it.but that doesn't happen to often .been in the business 20 plus years , re post if further ? ill try 2 answer them 4 you

[MuleShack]

I opened up the plenum this afternoon and found some rust pieces at the elbow of the fitting of the drain line. It was loose, so didn't look like enough to clog.

We have an air cleaner and those filters are clean.

The pan itself looked rusty on the bottom but I have no way to tell if it is leaking. I can only pull the cover back a few inches and didn't want to remove the whole back side. I suppose I can pour water in the pan and see what happens to it.

Your right, it probably is low on freon.

[Tom7227]

This happened to me a few years ago. The humidifier uses the same drain pipe although not through the fittings on the A coil. The water from the well was full of iron and the iron deposits clogged the drain pipe. Ended up with a puddle under the furnace. It took a while for my brain to figure it out and then it was pretty easy to blow it out until I could replace the pipe that led out to the actual drain. Doesn't take much to plug up a half inch gravity flow drain pipe.

[Whoaru99]

I opened up the plenum this afternoon and found some rust pieces at the elbow of the fitting of the drain line. It was loose, so didn't look like enough to clog.

Maybe, maybe not. I've seen loose stuff move around and cause intermittent blockages or restrictions.

As mentioned earlier, freeze up is pretty easy to detect. Start the AC, check how much air is coming out of a duct then let it run for a while. Periodically check the air from the duct and if the flow gets less and less the longer you run it then it's probably freezing.

Of course, now that you've been in the plenum you could just let it run then check it. If it's good and frozen you have plenty of time to have a look.

[MuleShack]

I suppose your right, being there is no "pressure" only gravity, it could be enough to prevent drainage.

[hitthebricks]

I had to replace the drip pan for the A coil this year. went to Northwestern sheet metal off Rice street in St. Paul, $175.00. They said the make a lot of these. It took a couple hours to remove and replace but it beat the $1200 I was quoted for a new A coil.

Just a possible solution if this is your problem

HTB