Why is my air conditioner condensation pan overflowing?
Condensation drain pans fill up and overflow repeatedly, forcing people to constantly shop vac standing water to prevent property damage and leaks. Because the underlying causes are hard to pinpoint, homeowners and renters get stuck dealing with recurring indoor flooding.
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.
Why is my air conditioner condensation pan overflowing?
- 1Having the landlord or an HVAC company clear the drain lineDid this help you?
- 2Putting preventative tablets in the panDid this help you?
- 3Installing a kill switch to shut off the system when water builds upDid this help you?
- 4using a shop vac to remove standing waterDid this help you?
- 5cleaning grime and clearing pipesDid this help you?
- 6pushing PVC pieces around the P-trap to tighten fixturesDid this help you?
- 7Take the trap and turn it up a little moreDid this help you?
- 8Checking if a p-trap is located further down the line in a crawlspaceDid this help you?
- 9Pulling the safety switchDid this help you?
- 10Clearing the main drain line using a shop vacDid this help you?
- 11Calling an HVAC professionalDid this help you?
- 12Killing power at the outdoor unit to prevent floodingDid this help you?
- 13Having maintenance clear the drainDid this help you?
- 14Using pan tablets to keep the drain clearDid this help you?
- 15Refilling the refrigerantDid this help you?
- 16cleared the clogged drain line going to the sinkDid this help you?
- 17considering drilling holes in the drain pan and bending sheet metal to create a custom trayDid 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.
“For the second time we got a leak caused by the condensation pan filling up.”source ↗
“Trap might not be deep enough and the air suction is holding the water in. Can cause big floods from roof top units into the ceiling.”source ↗
“Is this amount of standing water normal to have in condensate pan? It is always like this, even when it is not running.”source ↗
“just a month ago this pipe just started leaking a lot when our AC runs. Confirmed it stops when AC is off.”source ↗
“Our drain pan has been filling up recently where I've had to shop vac the standing water twice in the 2 weeks so I've been trying to determine the root cause and apply a fix”source ↗
“I don’t understand is this normal or is there an issue with the draining and water backing up?”source ↗
“there is a constant stream (not a drip) when the AC is on”source ↗
“Water does drain from it. But the pan always has about a half inch to an inch of water.”source ↗
“What other things should be looked at as to why the humidity is always so high. The AC seems to dehumidfy very poorly.”source ↗
“A new wet spot appeared on the ceiling and I went in the attic to check and it's coming from the ac.”source ↗
“the tray underneath the coil is very wet and rusted so I'm thinking of drilling some holes for the water to drain into and bend some sheet metal into a tray underneath and hook that to the drain line going to the sink?”source ↗
“When the AC is on it just blows air straight into the hot attic. Should that be capped?”source ↗
“My relatively new house had a leak by the AC unit today.”source ↗
“Today the pan was full of water but when I pulled the safety switch out it didn’t seem that high and the switch did not shut the unit off.”source ↗
“They said it happens when it real humid outside. I live in south Florida, 70% humid is considered a dry day here.”source ↗
Where this came up
People with this problem also raised
- 47How to clear a clogged AC condensate drain line
- 2Is air conditioner condensation normal or a leak?
- 15Why are my new gutters leaking from behind?
- 3Why is a puddle forming from a pipe outside my house?
- 13Why is my AC air handler wet and smelly?
- 2Why does my evaporator coil drain outside instead of the bathroom?