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airheatman, HVAC Technician
Category: HVAC
Satisfied Customers: 8327
Experience:  Furnace, A/C and heat pump specialist.
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Hi, thanks in advance for anyones help! We moved into this

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Hi, thanks in advance for anyone's help!

We moved into this house 6 months ago. Yesterday, for the first time since we moved into this house, we noticed a wet patch on the ceiling of the top floor.

When I went up there and took a look I found that there was water leaking from the bottom corner/edge of the evaporator unit.

There does not appear to be an external drip pan underneath the unit so the water is merely dripping onto the drywall that forms the ceiling. We have cut a hole in the drywall for the water to drip straight down through the ceiling and into a bucket on the floor. In this way we hoped to stave off any further damage of the ceiling drywall.

Today we had an A/C repair guy come over, and he gave a diagnosis of a replacement of the coils being needed and quoted about $1,500 to do the job. While I am not an A/C repair man, the diagnosis seems to be different than what I was assuming was likely -- that there is a partial blockage of the outlet of an internal drain pan to the PVC pipe that eventually exits outside the side of the house.

The A/C is still blowing strongly with cold air, and the leakage does not appear to be freon -- it is water condensation, I think.

I have a photo that I will upload if Just Answer allows me to do so. Thanks for your help, guys!
Hello.My name is XXXXX XXXXX I will do my best to help.Troubleshooting often requires meters and test equipment.Let's get started and see what we can do!
My first assumption would be as you stated, as stopped up drain.However if you have had a tech check that out, you may have a rusted pan in the evaporator coil. If the coil pan is indeed rusty, replacement will probably be necessary. Also there should be a secondary metal pan built to go under the coil to prevent overflow from wetting ceiling.Also would request drain float switch put in main drain so it will shut unit down if drain stops up rather than allow it to continue making water.
1500 is probably a somewhat fair price, but if you have doubts about the hvac guys honesty, I would call for another company to give a second opinion as well as a quote if coil is indeed bad.
Customer: replied 4 years ago.

That is a very old coil. The galvanized nipple is also characteristic of coil having a metal drain pan. The tech is probably right on with his diagnosis. Your pan is most like rusted through and coil will need to be replaced as a pan will not be available.
When replacing, request that secondary pan and drain float switch be added.
Customer: replied 4 years ago.

How do I know it's not merely a blockage? How would I access the pan to check whether it is a blockage?


Also, I am concerned about "spending good money after bad." If this is a major job costing $1500, should I be considering updating the evaporator to something newer rather than spending $1500 to keep an old, old unit going?


Thanks for your help!

You can take an air tank and disconnect drain and blow it out. If drain is clean (I would suspect the ac guy did this) and you still get a drip, pan is most likely rusted out. You would have to dismantle the coil to actually get to the pan.
In actuality if you can afford to replace the coil and outdoor unit with a higher efficiency system that would be wise , but expect to spend at least 3000 to 4000 to do this.
Customer: replied 4 years ago.

Thanks! The part that confuses me, however, is this:


Last night when it cooled off... I turned the A/C off all night. When I couldn't bear it anymore today in the heat I turned it back on, and it was at least 5 cycles of the A/C going an and off before the leak start again.


So the water problem occurs periodically, not all the time. If the problem were rust, whose location would likely be at the bottom of the pan (not on the side 1" from the bottom), the water would leak whenever the A/C unit is running. But that is not the case. the water leaks just periodically when the unit is running after about five cycles. That suggests an overflow, resulting from the exit being largely, but not completely, blocked.


What do you think?

This does sound like an overflow issue since it seems pan has to fill u p before the drip starts. I think I would get a second opinion before replacing the coil. But the coil is very old and a rusty pan would not surprise me.I have seen the pan rust in corners, at actual drain nipple etc, but I do agree that you would seem to get water shortly after it starts making water. I strongly suggest that second opinion.
Customer: replied 4 years ago.

I do greatly appreciate your help! Nearly done then :-)


Ok, what would I expect to pay for:


1) Overflow issue/blockage?

2) Replace coil?

3) Replace whole evaporator?

4) Replace whole system including outdoor unit?


We currently have 4 ton unit which is honestly a little underpowered for this house in Los Angeles.

Blockage issue around a hundred bucks. Coil is the entire evaporator (Called an evaporator coil). That normaly runs between 1200 to 1600, which is in price range he quoted. New evaporator and outdoor would be in 3000 to 4000 range (depending on size, brand and SEER) And if you decided to replace furnace also, another 2,000 for furnace.

Customer: replied 4 years ago.

Got it! Thanks for all your help :-)


You have been fantastic and will get glowing feedback and a tip ;-)


Also, along the lines we are currently thinking now, it seems indicative of a partial blockage of the drainage line to the outside of the house along the side of the house. The water that drains there appears to be not as much as I would expect but significant enough that it IS clearly draining.


If there is a partial blockage of this drainage, it would make sense then that the backup when the A/C is periodically cycling during the heat of the day that the partial blockage causes an eventual overflow, but when it's left off for a while, it drains sufficiently so that when A/C is turned back on it takes several cycles to overflow again.


If there is a blockage of this drainage as opposed to a blockage at the evaporator to the PVC pipe, what is the best bet to get the drain cleared?


I've heard about a product named Mighty Pump -- are you familiar and would you recommend this sort of approach?

Drain should be blow from inside to outdoors, I like to cut the pvc pipe and insert a hose attached to a nitrogen tank and open the nitrogen gauge to purge the line.This will guarantee there is nothing left in the line.It can be spliced with a tee to reconnect which allows a place to pour bleach to help keep it cleaned out. I would suggest even if drain turns out to be the issue rather than the coil that you get a secondary pan under the coil and a float switch in the drain.They actually make a TEE float switch which you could use when reconnecting drain after cutting to blow it out.
Customer: replied 4 years ago.

Ok, last question... LOL...


The blockage is likely to be at the exit of the pan.


How can I gain access and poke my finger in the hole and clear the blockage?

My suggestion is to purchase a few fittings like an elbow, tee and coupling. Cut drain close to the existing elbow and unscrew it, Then you can take a skinny screwdriver and poke in the nipple to make sure nothing remains in the drain where connection is at coil.
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