AC unit leaking water from top rubber seal
Condensation forming around the top pipe connections is leaking from the rubber seal and causing premature rust. Installers often dismiss this as normal, but the moisture is corrosive and risks eating through the equipment within a few years.
What the numbers show
Counted from the threads quoted below. How we count
- The most recent one is from October 2026.
- This comes up 18.7× more often in r/hvacadvice than across the site as a whole.
What people tried
Every workaround mentioned in the threads below. We haven’t tested any of them — and nobody here is claiming they worked.
Found another way around this?
Share your steps and trade-offs so fellow engineers don't have to reinvent the wheel. No account required.
- 1Taping up holes independentlyDid this help you?
- 2Adding plumbing putty or sealant around the fixturesDid this help you?
- 3Calling out a different technician than the original installerDid this help you?
- 4Ignoring the issue based on installer reassuranceDid this help you?
- 5attaching a hose to the upper spoutDid this help you?
- 6draining the hose into a mop bucketDid this help you?
- 7installing an attic fanDid this help you?
- 8Using a shop vac to clear out gunk from the condensate drain pipeDid this help you?
- 9Insulating the PVC drain line or sweating pipesDid this help you?
- 10Dumping vinegar down the open PVC pipeDid this help you?
- 11Installing a water sensor to shut the unit offDid this help you?
- 12Using a shop vac on the vertical pipeDid this help you?
- 13Adjusting the angle or pitch of the drain pipeDid this help you?
- 14Clean the coil yourselfDid this help you?
- 15Buy spray made for cleaning the coil and use it from where you took the photoDid this help you?
- 16Replaced the air filter with a new filter from a different brandDid this help you?
- 17Vacuumed or cleared the condensate drain lineDid this help you?
- 18Tried a less restricting filterDid this help you?
- 19Left the fan turned on continuouslyDid this help you?
- 20Checking the drain for clogsDid this help you?
- 21Checking refrigerant levelsDid this help you?
- 22Pouring water into the condensate pan to test for cracksDid this help you?
- 23Inspecting the lineset for missing insulationDid this help you?
- 24Monitoring coil icing and fan cyclesDid this help you?
- 25brush cleaning the coilDid this help you?
In their words
Unedited, grouped by where they were said, most upvoted first within each place, each linked to the thread it came from.
“Excuse me for being VERY dumb when it comes to this. This is in the attic of my house. It was leaking onto the plywood. Am i putting the AC too cold? How can I prevent this from happening? PLEASE any advice is appreciated!!”source ↗
“I have a 2 story house in a humid SE Texas region and my hvac units have been sweating for the last 2 years roughly.”source ↗
“The whole units are sweating on the return and exhaust plenums (sorry if I didn’t say it right. I’m not a AC tech and don’t have any knowledge of it I’m just a defeated homeowner looking for guidance) and condensation is forming on the outside of the ducts.”source ↗
“At this point I don’t know what to do with this anymore and how I can get this fixed.”source ↗
“I found water in the drip pan last week. I determined there was condensation that had made its way out of the condensate pan (obviously lol). When I found it I first checked the drain, no clogs and draining fine.”source ↗
“Tech came and took the cover off, filled the condensate pan with water to the brim, no leaks so no crack in the pan. Any ideas?”source ↗
“The unit is still leaking even though we have a drainage hose hooked up and the filters are cleaned.”source ↗
“How to access the underside of the coil?”source ↗
“One of my indoor units is leaking a lot of water directly onto the air filter, which is located below the evaporator coil.”source ↗
“The water seems to collect into larger droplets on the coil fins and then drops down onto the filter instead of making its way into the drain pan.”source ↗
“One thing I noticed is that there is a lot of water sitting/moving through the condensate drain line on the other system, while I don’t see much/no water in the drain line on the problem system even though the coil is producing a lot of condensation.”source ↗
“There’s plenty of condensation flowing and following the intended path as it should, but I’m getting some additional condensation dripping from the central area of the A coil.”source ↗
“The filter gets wet and some standing water collects on the floor.”source ↗
“Unfortunately we have been fighting with our ac for months. The apartment keeps putting bandaids on the issue rather than fixing it. This leak comes and goes with almost no rhyme or reason. The float switch also fills up randomly, which of course means the unit stops blowing cool air.”source ↗
“I notice a good amount of water is pooling on the filter.”source ↗
“It's coming out of where the rubber is sealing at the top of the pic (circled). It's obviously enough to have caused rust.”source ↗
“I was told by the team doing mine that this is how it is and "You don't get it leak proof" and got an attitude for asking them back to look at mine.”source ↗
“I always call them back for this stuff and they think I'm such a bitch but rust holes in a 5-7 year old hvac are unacceptable.”source ↗
“The water thats leaking out is corrosive and will chew a hole in a couple years.”source ↗
Where this came up
People with this problem also raised
- 48Water keeps getting in the house during heavy rain
- 30HVAC lineset leaking through the roof
- 4Can you service an HVAC system with leak seal in it?
- 14Why is my ductwork dripping condensation inside the walls?
- 2Why does my AC drain line keep backing up and leaking?
- 6Should I replace my HVAC system if the evaporator coil leaks?