In Wall A/c Unit - General Maintenance

[Andrew B.]

I have an in wall A/c unit in my personal home, and I'm curious if anybody suggests any type of annual maintenance to keep them running properly? DIY or professional suggestions are both wanted. The reason I ask is because my unit leaks water when it gets really humid (thank you North jersey weather). it only happened once this year, and once last year but I'm curious if there is a general maintenance step I could be taking that could keep this from occurring.

[Matt R.]

So, like a window air conditioner, but installed in the wall instead of a window?

Normally these are meant to slope towards the outside a little bit, so condensation will head for the outside.  The water from the evaporator (inside coil) normally drips into a tray, or a channel stamped into the steel on the bottom of the housing.  It then runs towards the condenser (outside coil).  On many models, the condenser fan is designed to dip into the water at the bottom, which tends to fling the water at the condenser, helping cool it off and work better.  If there's too much water to get rid of that way, it's meant to drip from one of the outside corners, sometimes from a drain hole in the sheet metal.

You might look around the edges of the unit, inside the house, for the mounting screws / clamps and make sure those are tight. If it sits on a brace or bracket or stilt outside, you might make sure that it allows the unit to slope away from
the house.  If you can reach it from the outside, you might (gently) poke a toothpick into any small holes near the bottom corners; sometimes they get plugged up with mineral deposits from the evaporated water, or leaves, bugs, mud, etc.  Or, apply a vacuum cleaner to those holes to see if you can suck out the crud.  Don't use a screwdriver or anything real sharp to poke with - you want to avoid poking a hole in the refrigerant (Freon) lines, which will be close by.

Other than that, clean the filter!  Often it won't be a replaceable filter like a whole-house furnace would have, but a piece of wire or plastic mesh that you slide out of the front of the unit, wash, dry, and reinstall.

If you get funky, musty smells, unplug it, and take the entire plastic front off of it.  You will see the evaporator coil taking up most of the front.  Put a plastic trash bag on the floor underneath it, and then hose the coil down well with your favorite multi-purpose cleaner (Windex, 409, Fantastik, Spic n Span, or equal), and maybe use a sponge or a wad of paper towels, gently, to wipe it down.  Don't bend or crush any of the thin aluminum fins on the front - just wipe it gently to get off any surface crud.  Let it dry, put it back together, and run it.  It will smell like the cleaner for a bit, and then it should smell better in general.

You can kind of do the same thing for the condenser, but it's usually harder to get to, because it's behind the outside sheet metal.  You can use a vacuum against the outside to get a little bit of dirt, leaves, bugs, etc out of it, which will help some.

If it has a cord and plug - it's not hard-wired - crank down the thermostat so it comes on and stays on for a while.  After 5 or 10 minutes of running, feel the plug and along the cord.  A little warm is OK but if it's really hot, replace either the outlet (if the plug is hot) or the cord (if it's hot along the cord somewhere).