My line from my exterior AC unit is dripping at the furnace. The dripping over time has caused rusting and we've had to replace the control board under it. It appears the root cause of the problem wasn't fixed. The pipe drips when the AC is running. I have re-insulated it (before it looked like it had poor insulation) and it is still dripping. Is there anything else I can do to fix it? Is there a proper gasket to put on the connection of the pipe to the side of the furnace that I need?

I've checked the condensate drain line and it appears it's working. I opened the furnace and there is some standing water in the pan but nothing high enough to reach this line where the water is coming out. The metal pipe on the right is the condensate drain line, and the two pipes above to the left are the lines to the AC. The larger line is dripping water.

Water under AC line

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1 Answer 1


I can think of two sources for this water: (1) condensate water overflowing from the a/c evaporator coil collection tray (2) water condensing on the cold low pressure (suction) refrigerant line and flowing down.

I think (1) is more likely.

  • 1
    Although I agree with the 2 items but it is totally feasible to have condensate form on the low pressure line and melt in between cycles I see this regularly where critters have chewed through the insulation or it was not in good shape from age, or lack of insulation from the original install.
    – Ed Beal
    Jun 7, 2019 at 19:27
  • I ended up cleaning the parts of the pan I could reach(it was extremely dirty) and snaking the condensate line. Also poured vinegar in the pan and saw it come out the line. Put it all back together and still appears to be leaking. I did all I could in my abilities going to have hvac come out next week.
    – jrowe08
    Jun 7, 2019 at 22:25

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