Hot Topics: Leaking Air Conditioner

Hot Topics: Leaking Air Conditioner

Here at we enjoy providing a place where home improvement novices and experts can come together to share ideas and advice. Inside our Forums, users can browse threads to see what exchanges are taking place on a topic of interest or start their own dialogue by posting something for the community to take part in. With over 250,000 members and counting, this resource is quite active so each week we highlight one of the conversations that may just help you with that next DIY project.

You don’t want your AC to break in the middle of summer! When there’s something fishy going on with your AC unit, our members are on the case.

Original Post: Leak from AC

jsnow Member

I have a recurring issue with the AC unit: there seems to be a bit of a leak (clear liquid, possibly water), and it seems to originate in the space between the beige and grey parts, right underneath the black box (the box itself is actually not plugged into power). What could be the cause for this leak?

Air conditioner with a leak

Highlights from the Thread

skaggsje Member

Your condensate pan is overflowing. Probably blocked drain. BTW, the black box is a humidifier.

WyrTwister Member

I would make sure that the water is shut off, going to the humidifier. In fact, if you do not use it, I would remove it and patch the hole with sheet metal.

Inside, it may be insulated. If so, use an equivalent or better insulation on the sheet metal.

As far as the condensate, while you have the hole open, I would inspect the coil, inside the plenum. In fact, make the sheet metal patch removable, as an inspection cover.

Use a wet vac and clean out the coil and plenum, as best you can. If the coil is dirty try to clean it in place as best you can. There are foaming coil cleaning products on the market.

Use the wet vac to try to unstop the condensate drain. Either vacuuming or blowing. Maybe use an air compressor.

Take a level & see if the whole unit is level both ways. A SLIGHT tilt towards the condensate drain opening is not a bad idea.

When completed, check the filter and replace as necessary.

jsnow Member

Thank you! I was trying to figure out where the drain pipe is on the outside - and I think it is the small white one in the picture here, but all of the videos I have seen, the drain pipe seems to be much larger. If the white pipe here is the correct one, how do I clean it? Is there an adaptor for the wetvac that I can use?

AC pipe through wall

skaggsje Member

I would check inside for the pipe. Where it comes out of the duct. See if there is a clean out.

WyrTwister Member

As far as an adapter, measure the Outside Diameter of the white pipe/tubing . Measure the Inside Diameter of the "fitting" on the wet vac hose. Go to the supply store and find the reducers you need. May take more than one. And, maybe, some duct tape . :-)

jsnow Member

Hi, a followup: I contacted an HVAC company, who came and filled up with freon (~3 lbs) but said that may not be the issue since there might be a hole in (I forget which part he mentioned). So that took care of the leak that I described above, but after a couple of weeks, the unit started leaking from the bottom. Any ideas? I am being told that I need to replace the entire HVAC system since it is old, but if there is any way to do this as a repair, that would be extremely helpful.

PJmax Group Moderator

The leaking water is caused by a plugged drain line. There is a pan inside the air handler that catches the water and directs it into a drain line. Look for a 3/4" white pipe coming out of the air handler.... probably on the left side that we can't see.

I see a drain line for your humidifier pointing downwards. You may have a condensate pump that pumps the water to that white line you found outside.

You contractor put in three pounds of refrigerant. That would indicate a leak in the system. The refrigerant has nothing to do with the water leak. He may have told you the evaporator is leaking. Based on the age of the system.... it may be time for replacement.

Look for the white PVC pipe and the pump as shown below.

AC humidifier

jsnow Member

Yes, I went outside and waited for the drain pipe to start draining - and it did; a lot of liquid came out of it in a spur. He checked the drain line - blew in the white PVC pipe and said it was fine, no clog. So I am not sure the drainage is an issue.

If the issue is with the evaporator, is repairing or replacing it an option? How would that compare (cost-wise) with replacing the entire HVAC?

And if I decide to have the AC replaced, does the furnace need to be replaced as well - given what the issue is; or can I request to have only the AC replaced?


Bob14525 Member

As to whether the leak can be repaired, it depends upon where it is and how difficult it is to find. If it's a very small leak, it can be difficult to find. Also, if the evaporator coil is leaking, it depends where it's leaking whether it can be repaired or not. If it's leaking at one of the "U" fittings on the sides of the evaporator, there's a good chance it can be repaired. However, if it's leaking in the main section of the evaporator, where the fins are, it's time to replace it.

The evaporator coil can be replaced by itself without replacing the entire system. However, depending upon the age of the system, it may make more sense to replace the entire system. The reason being, if the system is older than ~12 years old (typical life expectancy of an A/C system), if you replace the evaporator, the rest of the system (compressor & condenser) is still old and can possibly break down.

The evaporator coil or entire A/C system can be replaced without replacing the furnace. However, if your furnace is old or low efficiency (<90% efficient), it might be worth considering replacing it at the same time. About 5 years ago, I replaced my 30 year old furnace (looked similar to yours) with a new 95% efficient furnace. My heating bills dropped by ~25%.

Read more at: //