Window A/C - maintainence

Anyone here have window air conditioning units in their home? Is there any maintainence that should be done before the hot weather gets here other than cleaning the filter (and removing the outside cover - don't ask)?

Clean it really well. It can get some moldy mildew crap that can wreck your sinuses if you're not careful.

If you have an air compressor, I would blow any dirt out of the fins and housing.

I like to take off the inside cover and spray down the inside fincoil liberally with spray Lysol.

thanks for the help. I have two, one on the second story - so sounds like everything I need to do can be done from the inside. Great because I hate ladders.

I would definitely take the cover off and you'll have to pardon me as I always get the condenser and evaporator coils confused but I believe the outer most one is the evaporator (correction police please LOL !) and the inside, side of it, will accumulate a layer of dust that can become a thick felt and block the fins. Compressed air is ok to use but too much pressure you will bend the fins. Sometimes that layer is firm and air won't move it, so use a hose. Do be cognizant of the capacitor terminals, do not touch, and or any electronics if it has any like for the control panel, remote etc. I discovered this on mine last year and cleaned it but good, it took a little time but it gets complete air flow now.

I find with black mold the cause is obviously condensation in the cold air duct, most likely from being shut off after running in high humidity, I used to crank mine, (as my end of the house just gets hot from this time of year until september) then shut it off, room nice and cool all night. Bad move, the duct was covered with black mold, and its Styrofoam, hard to clean, I carefully sanitized it with a house hold cleaner and wiped it clean, upon inspection a few days ago, no mold. I run it thermostatically now and let the compressor kick on and off, set the fan on low and it does not build up condensation, trapping moisture and creating the mold problem, that duct needs air flow to dry properly in my opinion.

The condenser coil usually is easy to vacuum or blow out with low pressure compressed air, this year cleaning my window unit was easy, last year I literally took it all apart, its an '02 kenmore, 8000 btu, I really like it, I did have to replace the dual capacitor, local supply house had one real close in spec's and size it was 12 bucks, can only imagine what a service call would have cost for a cheap part like that. I've kept 'er running and cooling 10 years now, and I cannot say how long that coil looked like it does in the photo, just that I caught it in time and it seemed like common sense to look these over and clean annually.

Mine did not have a weep hole and I am not sure why, but disagree with it, just seems to want to rust out the housing and whats near it so I protected the coil and let the condensate out, the old units always had them, maybe I am wrong or indifferent, why would the evaporator coil need to have the bottom immersed in water. It said not to drill a hole but that seems to be due to puncturing the coil, so of course that makes sense, but at least it won't rust out, hold stagnant water and make a mess when you take it out in the fall.

This was really caked on there could have been years worth, til I finally decided its good measure to clean these, this would have had to shorten the compressors life if I understand correctly.

I have 2 , 1 in the bedroom (2 or 3 years old) and 1 in the living room New last year. Both were cheap ones from Wally world. My feeling with them is they work leave them alone. If they croak I'll just replace them. All I do is put a cover over them for the Winter.

I use many window units in rental properties. Also have cotton wood trees, so in a year my condensors look like yours. To solve this problem, I cover the outside of the A/C with aluminum window screen and drill holes so the water can"t be splashed against the condensor. About once a month, I take a wet rag and roll the lent off the screen. This saves me a ton of time from taking units apart every spring.

Before someone yells at me for drilling holes, I know the water does some good as long as it doesn"t cause the crap to collect on the condensor. I drill holes to prevent the rest of the A/C from rusting too.

So in theory, the evaporator water does some good, but in MHO it does more harm than good.
George

Hi George ! About the same time last year you mentioned this and the window screen. I think much of what was on this one, may have been from NJ as it was in my home there when I bought it, but after 1 season here, after last years cleaning, I did not have any screening on the cover vents, darned thing was clean! I think we have those trees here, but not nearby maybe a few miles away near the river, used to be an island in the river that was left alone for 100 or more years and there was some big trees on it, was a cool place, but they leveled it and put condos in 5-6 years ago, I recall all the lint or fuzzies in the air, we don't seem to have that here thankfully, but that screening is an excellent idea, I put a makeshift one on my tractor as the grill was gone before I got it, sure catches goldenrod fuzzies and keeps the radiator clean, cool etc.

Hello Billy NY,

The coil that gets hot is the condenser. The cool coil is inside (the evaporator). Cleaning the coils will certainly help the thing work better. Drilling holes, or pointing the think to the ceiling is NOT necessary. Condensate accumulates in the outside coil pan. It helps keeping the system cool, and therefore more efficient. Make sure the condensate path is open between the front and rear coils. Otherwise the unit will short cycle, and not cool properly.

Guido.

I hose off the out side coil on the one in my computer room. Worked for a guy one time who did AC units and he said it was a good idea to clean the outer coil at least once a year if not more. Plus clean or replace the inside filter

IMHO, putting plastic cover over metal is a formula for causing rust. Ask anyone in the A/C repair business and they should tell you the same thing. Plastic only traps moisture. A/C should vent and dry out. So why cover them up? You don't cover them 9 months our of the year, why winter?

Buy not cleaning the condensor, you may burn out the compressor. There is always the remote possibility you could cause a fire. I knew of a person that this happened to.

Also know of a person who was mowing and blew all the crap from mower towards a new A/C. What a mess. Condensor was choked.
George

I believe the cover is intended to cut down on the cold air entering the house. Also thinking you wouldn't want rain getting in there and then freezing up. I put a cover on the outside and then cover with blankets on the inside to prevent drafts from the cold.

(quoted from post at 16:48:57 05/23/13) Is there any maintainence that should be done before the hot weather gets here?

Click to expand...

All the crud should be removed from the bottom of the case and the coils cleaned. At the minimum carefully use a vacuum with brush on the coils. The best is to use a specific coil cleaner chemical. In between would be to wash them off with a detergent. At my work place (University) I had 2 windows units to keep the equipment cool in the summer months. The UMRs (Utility Maintenance Repair) guy was suppose to cover them for the winter and clean them in the spring, but he/they never covered them and only cleaned them when they were so dirty they stopped working. One summer, out of desperation, I loaded up a spray bottle with detergent and water and proceeded to spray the coils on the dirtier window unit. I had no way to thoroughly rinse out the detergent. When I turned it on there was a flurry of bubbles blowing outside, it was on the 3rd floor. I'm sure you use a similar maintenance procedure on your tractor and combine radiators, don't you?

Front to rear condensate path open: adding that if it's not open and your AC is pretty level, it will run out the front and your carpet will get wet. BTDT

Didn't know it was clogged. Not clogged any more.

Condensate is picked by the slinger ring on the condenser fan and blown across the coils. The heat of evaporation of water is enormous and greatly aids in the efficiency of window AC units. Cooling the high pressure liquid reduces the head pressure on the compressor since pressure and temp are directly related. It takes watts of power to compress freon at high head pressures. The lower you can get it the lower the wattage required to compress a given volume of refrigerant.

What you pay for this efficiency is that the water that is slung on the condenser coil is wet and as the condenser fan blows air across the coil, any dust in the air mixes with the water and makes goo, like in the picture.

So, every year or so, depending on your situation, the unit needs to be removed and washed out as some have mentioned. If you don't clean the coils you reduce the air across the condenser which means you don't cool the high pressure freon as you should and the overall system heat goes up driving your light bill up and your cooling ability down. It's no big deal for an entrance level fixer upper. Just be careful with the coils and get the short screws back where they were. Short screws in the right places don't punch holes in refrigerant lines.

To clean the condenser effectively you need to get at the inside of the coil meaning you need to remove some sheet metal. Be extremely careful in cleaning the fins as they are very fragile and the spacings as you had when the unit was new need to be maintained (no smashed fins) to allow for proper air circulation and efficiency. Also take care to maintain the sealed system intact so that you don't open any seams and cause your freon to leak out. No freon, no cooling.

Mark

The cover keeps cold air out of the house. The front of the AC is open to the house. The biggest source of rust is in the condensation water developed as part of the refrigeration process.

Most ACs are protected to a degree from this known source of rust.

Mark

Mark, thanks for the details on the basic principle of how the A/C works. I always wondered how these darned things do what they do to cool air and make things comfortable.

So in essence, more modern units went with the slinger so that it cools the condenser more efficiency by making use of that condensate in the pan. However like you say, that creates the problem above which does as you describe, makes the compressor work harder to compress the refrigerant, if those coils are hotter because the air flow is restricted by the felt like sheet of dust, like in the photo.


What I wonder is, like the old units and they worked fine, maybe more wattage but still, is this "slinger design" that further cools or consistently lowers the coil temperature further than the previous designs that did not sling water on the coil, really any better, given the propensity to collect dust and do the above, mind you which was years worth, maybe since new. I would imagine one seasons worth may or may not be nearly as much but after some run time, its likely to still coat enough to restrict the air flow and then you are no better off than if it was not slinging water because the coil is not 100% clean. I would assume there is some loss built into the coil size and or how the unit is built. I am now wondering should I silicon up the weep hole or just leave as is, its nice to know the coil stays clean, per the almost nil accumulation from last season, it needed almost no cleaning at all, seems to me you are right the increased dust accumulation, all makes sense now, thanks for posting this !

This has turned into quite the informative thread- THANKS EVERYONE!

Texasmark hit the nail on the head as far as what the slingers do on the condensor fan blades. Actually the older versions also had slingers and did this to an extent but still had a drain extend out the back for the majority of condensate to flow. The manufacturers do not care if they develop a machine that needs to have a higher degree of maintenance to maintain the rated efficiency....all they care about is the efficiency rating as it is tested in laboratory conditions. Kinda like gas mileage estimates in a car or truck !!!!

The dirty condensor (outdoor) coil is responsible for rejecting the heat transferred (via the refrigerant) from inside the house plus the heat of compression added to it by the compressor. As stated by Texasmark, the pressure and temperature of all refrigerants is directly proportional and it requires more horsepower (wattage) to do the work at the higher pressure caused by the airflow blockage created by the crusty dirt accumulation on the coil.

Efficiency goes down dramatically, the system runs too hot because of the high head pressure, the compressor begins running hotter because the warmer returning refrigerant doesn't cool it properly and eventually the compressor will cycle on its external thermal overload (internal on most single phase compressors of a capacity larger than around 12,000 btu). It becomes an endless circle unless it is kept fairly clean by annual cleaning.

WWGrainger will sell a acid based coil cleaner called "Foaminator" for around $14.00/gallon. It will foam profusely and force unbelieveable amounts of unseen dirt from between the fins. It is to be diluted and sprayed on with a pump sprayer and rinsed with a hose. It is friendly to the environment. Works wonderfully, just follow the directions.

George Marsh hit on a solution.

Slinger rings have been on AC's for as long as I can remember and that's back to the mid 60's when I used to moonlight at an appliance repair shop. They'd run a spring special on window units, Gulf Coast where AC is an absolute necessity and lots of older houses without central. Come to your house, pull your unit, take it to the shop, clean and repaint as necessary, return the same day. Did a good business.

I have resolved myself to the fact that every 2 years the units will get pulled and cleaned. As a result, I have reduced the size of my units to get the weights down.

Now here's the kicker.

In one area of the house I have a current electronic controlled, not manual like not too many years ago, 15k BTU that is doing a better job of cooling than a 24k that I replaced for a lot less money to operate. In another area a 10k has replaced a 14k with the same results. I have a 2400 sq ft house and with power at about 11 cents a kWHr my power bill in the summer runs around $130-150 during July-August.

House is well insulated, lots of trees and by using window units rather than a central unit, the cycle cooling efficiency is much better and there is no loss to duct work in the attic which amounts to a lot. Don't believe me that attic losses are high, when your central unit kicks on, what comes out of your duct first? Hot air. Then by having numerous area serving units, if you aren't using an area of the house you don't have to pay to keep it cool. Just turn off the AC.

For me, there is absolutely no comparison between the performance of the new electronic and the older manual controlled units. I can give it to you scientifically if you want it as to why.

Mark

I just pulled my current light bill which shows usage for 12 months. Last year my kWHr usage was:

June 704
July 979
Aug 1267

Cooking and heating are propane. This includes a 175w Mercury Vapor area night light that runs dusk to dawn.

Mark

Thanks for the tip on Foaminator. Have a WWG in the nearest town.

Mark