Important air conditioner question!

Well, it’s important to me, anyway. :wink:

I live in a duplex that doesn’t have central heat and air (as so many places to live in Nashville don’t, unless they’re new.) I’ve tried using window units for AC, but it never works-- for some reason, I can’t seem to find one that really fits, water leaks in, etc. There IS a unit that was sort of… semi-built in at one point. Basically, they took an air conditioner and then sealed the window completely around it. The problem is that I don’t see any way to really clean it and I’m very nervous about what might be in there (weird mold, etc.) There is so much mold in this area. So I’m really reluctant to use it. Is there ANYTHING to be done about this??? Is just getting a filter going to do anything? What is the likelihood that weird things are lurking in it, just waiting to get sucked into the whole duplex? Is there any way to clean it without taking it out (which can’t be done, so it’s never been cleaned since installation, I’m sure?) All advice appreciated and needed!!

A window A/C is a simple machine. They typically do not use filters. The air is drawn in from the front of the coil; the surface that is facing you. It is drawn through a very small duct and you feel the air coming out–usually above the coil.

The surface facing you is the surface that will get dirty. Take off the grill or other decorative grid, exposing the coil. If the coil is visibly dirty you can take any mild detergent (like 409 for example), dilute it and spray it liberally on the coil. It will run down into the condensate pan. (often called the drain pan) If the coil is very dirty (which will be visibly apparent) you can take a common men’s pocket comb and “comb” the “fins” on the coil. Always comb vertically, **always. ** Take care to not “bend over” any of the fins—they are very fragile and bend over very easily. (and will give you “paper cuts from hell” if run your fingers/knuckles over them) Since the coil has a different “fins per inch”, the comb will not match up perfectly with the coil and you could easliy be bending over fins while you clean/comb the coil. So, don’t comb the coil unless it needs it. If it does, lighty “skim” the surface with the comb to remove the gunk. Refill your spray bottle and spray fresh water to rinse.

The coil sits in a small pan that may not be entirely easy to see. It’s there though. That drain or condensate pan can grow some nasties, like certain bacteria or mold etc. (certainly not extremely common though) From an HVAC supply house (& perhaps from the net) you can get antibacterial condensate drain pan tablets. Once a year (right before summer) put a tablet or 2 on either side of the pan and the water from the airconditioner will melt them & kill the nasties.

This generally isn’t necessary anymore, unless you live in a VERY humid area. Modern window A/C units cleverly make use of the condensate water to improve efficiency. The exhaust fan, which blows air past the hot condenser coils, is arranged so that the condensed water is continually sprayed by it onto the condenser coils, helping to cool them via evaporative cooling. Pretty clever.

Also, most A/Cs do have some sort of dust filter to keep the majority of airbornef crap off the evaporator coils, either a thin foam pad or a fine mesh screen of some kind. Usually, this is fairly easy to pull out and clean, something you should do about once a month during the operating season.

I do very little work with window units. I’ve seen some with filters, some without.

The arrangement you’re describing is accomplished with a “slinger” (which you probably already know) The slinger is attached to the fan blade assembly and the water is picked up and flung against the condenser coil. (improving the efficiency by transfering heat into the water & through evaporation lowering condensing temp & pressure)

I agree that the issue of bacteria is reduced in lower humidity. I have never put those tablets in a window unit, however in a central system the enviornment that the evaporator is in is already wet, dark and inherently humid. (although usually around 55° when the unit is running) When the unit is not running there is almost always some nominal amount of standing water in the drain pan, and it is a decent enviornment for bacteria & mold if there is some food source. To the extent this is/may be a problem it is more common on central systems, and larger commercial/industrial systems. I have seen it however on simple residential systems, although as I said earlier, it’s not extremely common. Common enough in the midwest though that I see pans that need it about a dozen times each year.

One other thing…if you clean your own coil, be careful where you spray anything…and unplug the unit while you’re at work.

This is a VERY humid area-- SO much mold around. So everything I saw mentioned looks like a wonderful idea. I would really like to use this AC unit this summer rather than having to worry about finding another window unit (they just never seem to fit right…) I will say that the few times I tried to use it last year, the air blowing out of it smelled EXTREMELY moldy/musty/mildewy. This is what I so want to avoid. What caused it, exactly, do you think?

Thanks, y’all! :slight_smile:

I don’t know how handy you are, or how strong.

The window unit is sitting in a metal housing or cabinet. That outer cabinet, or shell, is just a retangular metal box, open on both ends.

The air conditioner itself sits on a frame, or chassis, and it slides into the cabinet. It is the cabinet that is sitting in the window, and what the framing etc is up against.

The air conditioner is removable from that cabinet, without disturbing the cabinet, window, or how it’s framed in. The cabinet remains in place.

It slides in and out from the front. (inside the house) If you unplug the unit, you will see 2-4 screws on the side of the cabinet, near the front, that hold the A/C in the cabinet. Remove the screws.

Get a grip somewhere, and tug on the air conditioner. It’s not entirely easy, but certainly doable. The unit will slide out, leaving the cabinet in place. It will weigh around 100 pounds. (?? give or take) It’s best to have 2 people to do this, but it can be done with one strong, agile person.

Take it to the driveway. The coil that faces the interior of the house is the evaporator . There is a very similar coil (the condenser) that faces the outside of the house. You can take a garden hose and clean both the coils. Be very careful not to have the hose on high velocity—you don’t want to spray water into the motor or electrical components. You can use a mild detergent and rinse with water. The drain pan that the evaporator sits in will be easier to see. Clean out the drain pan.

You can do this.

Let it air dry for a couple hours before reinstalling, and powering up. Be careful.