Dripping noise from the bathroom vent when the air conditioning is on?

Question

At times when the air conditioner is running there is a dripping noise coming from the fan unit in the bathroom that is close to the furnace unit. As soon as I turn on the fan the noise goes away. It only takes a second. There is no sign of water or water damage, but I am afraid it could be where I can't see it. Any ideas what it could be that is causing the noise?

Answer 1

Water dripping off the coils. Really check that it is dripping into the drain line here. Just take a good flashlite and go up there and inspect what you can see. This could be a problem that will not rear its ugly head until you see the mold growing out of the wall. Hopefully all you will see is water dripping into a drain or just a tube running outside with no water stains.

Answer 2

The noise is normally the condensation line from the ac that is dripping into the pea trap of your sink.  It usually isn't anything wrong, it is normal for the ac to create condensation.  The only problem is that it will drive you crazy.  If you call an AC guy, they can normally fix it by making the line not drip directly into the standing water of the pea trap, thus eliminating the noise.  The water will still be running into this drain pipe, but you won't hear the dripping noise.  

A totally seperate problem is water dripping from your secondary condensation line.  This is normally outside in a place that you will see it dripping so that you can call to have it fixed.  

IF WATER IS DRIPPING FROM YOUR OUTSIDE CONDENSATION LINE, YOUR MAIN CONDENSATION LINE IS CLOGGED UP AND YOU NEED TO UN-CLOG IT!  If you don't take care of the problem then you could have serious water problem from the drain pan in your attic.