Window Air Conditioner Noise From Rain?

May 4, 2011 7:56 AM

Did rain cause my new window air conditioner to make a spattering noise or was it normal operation of the unit?

I live in an apartment and had to ditch my portable air conditioner due to the vibration bothering my neighbors. Yesterday I bought and installed a new Frigidaire 6,500 BTU unit I got at Lowe's. It was working great until about 5:30am this morning when it started making a sputtering/spattering/popping noise every few seconds until I turned it off at 7am. It was not that loud but just enough to keep me awake.

After a little research it seems like the sound was from water bouncing off of the fan blades. I read that newer units use the fan to splash water onto the coils to increase efficiency (here). I am worried that the sound might be part of the normal operation as I know condensers drip water. If that is the case, I will have to get a different unit.

However, it was raining this morning (although I'm not sure if the rain started at the same time the sound started as I didn't notice the rain until I left the house at 8am for work) and I think maybe the rain was the source of the water hitting the fan.

My dilemma is that I can't afford to have another sleepless night. I am willing to go get a different model and install it tonight but I don't know if that will make a difference. Does anyone have any experience with this that can weigh in? Do newer window units make that sound all the time or is the rain the likely problem?

Thanks to anyone who can offer any insight!

posted by flyingcowofdoom to Home & Garden (7 answers total)

It's pretty common for the AC unit's I've had. Making sure it's tilting slightly downward in from front to back helps water drain quicker on some models.
posted by samsara at 8:07 AM on May 4, 2011

Response by poster: Thanks, samsara. Do you mean it's common at any time or just when it rains?

--FCOD
posted by flyingcowofdoom at 8:09 AM on May 4, 2011

When it rains, but also if it's really humid out.

If you're dealing with humidity, you're going to want to powerdown the AC and let it thaw/drain every so often. I had one last year that turned into a solid lump of ice inside.
posted by robocop is bleeding at 8:17 AM on May 4, 2011

It's common for water from the evaporator (the inside coil) to drain to the outside and pool at the bottom of the condenser (the outside coil). It noticeably increases efficiency and reduces the amount of water that drips onto the ground. Usually the drain level is set higher than the fan blades so make sure your drain hole(s) are unplugged and that the unit is sloped the proscribed amount.

robocop is bleeding writes "If you're dealing with humidity, you're going to want to powerdown the AC and let it thaw/drain every so often. I had one last year that turned into a solid lump of ice inside."

This shouldn't happen if your unit is operating correctly. Freeze up during periods of high humidity is often caused by a dirty coil. You can clean the coil by taking the unit to a U-Do car wash and using the spray wand to clean the coil. Direct the spray directly into the coils from the front from 18" or so away and pretreat the coils with some simple green. Also make sure your filter is clean and in place.
posted by Mitheral at 8:28 AM on May 4, 2011

Response by poster: Thanks Mitheral, I will check the drain and the slope. I'm thinking of fashioning some sort of "roof" for it, maybe using a plastic bin lid and duct tape, to prevent the rain from getting inside. Does that sound like a good idea or an idiotic one? Thanks again!

--FCOD
posted by flyingcowofdoom at 8:59 AM on May 4, 2011

That sounds like a good idea actually, might do something similar myself as it's a chore cleaning all the "tree debris" in mine once it comes time to pull it out for the Fall.
posted by samsara at 7:51 AM on May 6, 2011

flyingcowofdoom writes "Does that sound like a good idea or an idiotic one?"

As long as you don't significantly obstruct the vent you should be fine putting a little roof over your unit. But there should be lots of free space, say an opening left, right, and rear at least as big as the vent opening on the top of the unit. And try not to cover it in such a way that flow from the vents is redirected towards the rear coil area.
posted by Mitheral at 1:31 PM on May 6, 2011