It's starting to hot in Texas. I have a refrigerated air window unit in my office so I don't have to cool the whole house down to remain comfortable while answering iFixit questions. It has a removable plastic filter on the inside of the house that can be removed and washed. Behind that are the radiator coils. Those are dirty and I would like to clean them without making a big mess. Does anyone know how to do this and any other yearly maintenance things I need to do before starting it up for the year? To start use a vacuum cleaner with a soft brush hose attachment to get rid of the loose stuff. Then you are going to want to use a degreaser/ cleaner to spray on the evaporator. I would suggest a foam based one such as this to keep the mess minimal. You may notice the product I suggested is self-rinsing, which means it will only need wiped off. To wipe it off between the fins use a fin comb. Fin combs come in different sizes and styles. To pick the proper one measure the number of fins per inch and purchase one that has the matching comb.

Most of those are plastic. I could not find one like mine which is more like a disposable razor with different sized interchangeable blades. is uv air purifier safeI've got 10 combs/blades for mine. air purifier dogClick here for an example of the plastic one I have. do air purifiers help with cigarette smokeThey seem to be coming in some kind of a rotating circle set up now. These can also be used for straightening out bent fins. They also make universal fin combs. Please click here for an example. The universal ones do a good job for cleaning ( I have one for that purpose only.), if the fins are not bent, I would not recommend using one to straighten bent fins. You will want a bucket of water and some paper towels for cleaning the comb between strokes.

Insofar as recommended maintenance. Clean and straighten out the inner and outer fins on both the evaporator and condenser. That will ensure good air flow and efficiency. Clean the fan blades and if the fan has an oil port add some oil (3n1 electric motor oil). If you have a clamp on amp meter use it to compare the amperage draw of the unit to the rated amount on the specifications plate provided by the manufacturer, if there is more than a 25% difference you may consider having it professionally serviced - if you are not happy with it's performance. Freon systems are closed systems and if they are leaking it is most likely through a compromised piece of metal or a joint. With age compressor motors do tend to draw less current, so a difference in plate rating and actual current draw does not always indicate a loss of freon in the system. You can do what is called a wet bulb test. Use a quick reacting thermometer where the air is coming in to be circulated. Take another quick acting thermometer, wrap it's sensing part with a wet paper towel, place it where the air is leaving the unit to "cool" the room.

Let the AC run for 10 minutes. There should be approximately a 20F difference between the two if the system is in good order. I don't think it can be done without some mess ... condensation has probably glued the dirt/dust to the coils... Take it outside to brush and wash/rinse with soapy then clean water would be, IMnsHO the best way. if you have to do it inside you might get by with putting down a tarp (or using bathtub/shower stall) and using a hand pump up sprayer (like for liquid weed killer, or deck wash/sealant) to get some pressure behind the water. These units (all AC units actually) lose freon (coolant) as the molecules are so small they pass through most rubber hoses & seals - that affects efficiency of cooling. Take it, or call an AC specialist to come over, who can run a pressure test and top off the coolant (which also contains pump lubricant). As always "if this answer is acceptable"... you know what to do. Apartment complex I was at... Mexicans Really Good at these tings...

Pull unit, unplugged, hose down. let dry over night make sure is dry. Mine cleaned nicely three times last summer & one before. Dusty here in Arizona. Use a can of compressed air. Always be careful not to bend or displace the fins on your coils. If the fins are not damaged do not touch them with anything. Cleaning your air filter regularly and checking your coils twice a year are two of the most essential preventative maintenance tasks you can perform on a window unit Properly taking care of your air conditioner coils increases the air conditioners usefulness and life expectancy.  Getting down the gritty details of cleaning your air conditioner might not be as difficult as you might think. Much of it is routine maintenance you would be doing in part anyway, and a few cleaning tips you can easily master will help the chore even easier. You Will Need a Few Items Coil cleaner (this can be found in most hardware stores) Compressed air in a can Step 1 – Remove Debris and Trash

In the area of the yard around the air conditioners housing, make sure there are no debris or excess dirt.  If the air conditioner sits at the corner, especially there will be a collection of dead leaves, broken branches and other similar trash that should be picked up on a routine basis as it can clog up and cause problems with the air conditioner.  It can also make the area look more inviting to small wildlife like snakes or mice. These tiny pests can make a mess and chew on wires if they try to make a home in the air conditioning housing.  Snakes in cold weather will look for someplace warm and dry to curl up so if you live in an area where these reptiles are known to inhabit keep an eye out for them. Step 2 – Turn Off the Power Before going out to clean the coils, turn off the thermostat.  Wait a few minutes to make sure it cycles down then turn off the power from the main switch outside.  This will keep you from getting a very nasty shock if you accidentally touch anything. 

Powerful voltage surges through the machine and you don’t need to experience anything other than cool, crisp air.  Give the electric current a few minutes to dissipate before removing the housing. Step 3 – Remove the Housing To remove the housing start by using the screwdriver to take out the screws being careful to put them in a container or bag so as not to lose them then carefully lift the grill off and set it aside. Step 4 – Blow Out the Coils Locate the air conditioner coils. One of the reasons you should never use a hose to clean the grill will become apparent the second you see the coils.  It is natural for dust and dirt to accumulate on them, and if they get wet from the hose water you have a cloggy, messy hard to remove crusty crud all over the coils.  Holding something over your nose use the compressed air to carefully blast and blow out the dust and dirt then use the small brush to really clean them out as best you can.  You might have to give more than a few blasts of air followed by scrubbing to really clean them if they have not been maintained well.