Why is cold air blowing out of my AC drain line?
Cold air blowing from the condensate vents happens when the air conditioner is running. While covering these lines stops the airflow, it causes the system's air pressure to create a thumping noise in the drain.
What people tried
Every workaround mentioned in the threads below. We haven’t tested any of them — and nobody here is claiming they worked.
- 1Installing a P-trap in the drain line
- 2Putting caps on the drain pipes
In their words
Unedited, most upvoted first, each linked to the thread it came from.
Where this came up
People with this problem also raised
- 4Water spitting out of pump vent pipe
- 3Why is water dripping from my furnace when AC is on?
- 2Cool air leaking from gap around AC copper pipe in attic
- 4What is this extra pipe dripping into my sink drain?
- 24How to clear a clogged AC condensate drain line
- 5Car heater blowing cold air even with good coolant and thermostat