A Basic Clean for Outdoor AC Units

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Introduction: A Basic Clean for Outdoor AC Units

With summer approaching soon comes the time to turn on the AC to keep the house cold. You might notice that your electric bill spikes up more than expected or that your house is just having trouble staying cold. If it's been more than a few years sense your last AC unit cleaning (or you cant remember ever having them cleaned) then its probably time for a clean. It's a fairly easy process so save some money by doing it yourself!

Step 1: Safety First

Whenever doing ANY work with electronics its important to turn the electricity off and check voltage on the unit with a multimeter. Again, DO NOT WORK ON LIVE ELECTRONICS. For this particular project the risk isn't as much to do with shock (though this still exists and adding water to the mix is even more reason to be cautious) but more to do with fear of the unit turning on and spinning fan blades. Most units should have an electronics box near the unit on the outside of the building. Open it up and flip the switch to the OFF position.

Step 2: Tools and Equipment

The tool list for this project isn't a long one. A ratchet set, flat head screwdriver, a multimeter, and maybe a mallet are all you will need. I prefer using a ratchet set over the flat head simply because I find flat heads tedious to use.

Step 3: Disasemble

The metal shielding surrounding the unit needs to be removed. Go around the unit removing the screws holding the shield on and once they are all removed it should come off with little trouble.

Step 4: Clean the Unit

Using a garden hose with low/no pressure spray the outside to remove buildup of dust, dirt, leaves, and whatever else is stuck on the side. The units pictured are extreme examples of buildup. Much less buildup can still cause issues in cooling. Start by spraying off the outside at an angle and the buildup will come off in a 'Peeling' fashion. Then finish up by spraying from the inside out to clean out debris stuck within the fins. (When the buildup is high the fins wont allow enough water to get through to effectively clean the outside without first spraying the outside) While the unit is open I clean out any debris that has built up at the bottom of the unit. Continue spraying around until the unit appears clean. Use very low pressure to avoid bending fins, just an open hose end should do.

Step 5: Reassemble and Cleanup

All that's left is putting the unit back together, cleaning up, and turning the electricity back on. You should notice an improvement in cooling in your house and you didn't have to spend $100+ to get it.

Step 6: Notes

Final notes: Not all units are the same. This second unit pictured is different in that the side shielding is "capped" by the top piece instead of screwing into the side. Your unit will more than likely differ slightly from the two pictured but the concept is the same regardless of the unit.

Also, this is a very basic cleaning of the units. It will improve efficiency greatly in the unit. However, a good professional service will be much more thorough.

Read comments below for additional ideas anddiscussion

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    41 Comments

    I really appreciate the time taken to write this informative post. Regular maintenance of electronic device is really important, having an annual air conditioning repair and cleaning services of professionals such as estesair.com, http://www.amtekair.com/ and many others can keep your system work more efficiently working for long duration.

    Now, everyone go take your units apart... I need the extra money.

    No No No! First of all as a HVAC technician you learn to never trust the breaker. I see it from time to time that you turn off the breaker and the unit still has 240 volts or more. This Instructable is not recommended for people who don't have a good understanding of electricity. The condenser fan has enough power to slice off fingers or break an arm or wrist. Also throwing water into the mix your asking for an accident. We USE multimeter's to double check the power is off.

    The condenser fan blows upward sucking dirt, grass clippings, and other particulates into the coil from the outside in. So you spray from the inside out to flush it out and not lodge something in deeper.

    To do this we generally take the top or the fan off. Problem is that the wires go to the contactor and to a capacitor. There's a possibility that contactor has 208+volts, and the capacitor can still deliver a massive shock even if the power is off since it can store a charge. Again a multimeter is a must and good understanding of electricity. When your putting the fan back in make sure there are no loose wires to get caught in the fan; use zip ties.

    Also the use of caustic sprays to clean condenser coils are not recommended because it can potentially strip protective oxide finishes causing the metal to further deteriorate. Not to mention if you don't completely rinse it off that too will eat the coil. The caustic coil cleaners are designed for your evaporator where the metal is thicker and condensation will further rinse off anything you might have missed.

    In order to prevent breaking your warranty use a solution of simply green or a detergent to clean really dirty condenser coils and stay away from acids and bases unless it's your evaporator.


    And OMG no, you don't need a ratchet set and god forbid a mallet. First and foremost you need a multimeter, set of nut drivers, needle nose pliers, Flathead/Phillips screwdriver, and some zip ties to tuck away extra wires. I'm considering making my own instructable where I'll show how to clean and check all the component to make sure nothing will break down in the summer.

    I have something better, as far as safety. I stood over my A/C installer and demanded they install a 240 V AC plug on the A/C unit, that plugs into a socket on the breaker box. Now when I need to do repairs or maintenance, I can unplug the unit and know it's dead. This is the same form of safety that is routinely performed when repairing vacuum cleaners, power saws, and the like. I am not comfortable working on any equipment that is hard-wired to the line through a box. One bump of a lever, or a sticking switch, and you're live! I have never seen electricity "jump" through a plug that has been pulled!

    Before the wet cleaning is performed, a shop vacuum should be used to remove leaves and other dry matter, both inside and outside the unit.

    Im surprised your installer obliged as that is against electrical code and would be failed by any inspector. A/C units are to be hard wired, Just as hot water heaters are, with a means a of disconnect, within sight.

    It is not against electrical code. The installer put in the disconnect box as usual, per code, but instead of hard-wiring the A/C unit, he put a socket in the cutoff box, and a cord/plug on the A/C unit. Read the rest of the comments on this subject! The first thing that is repeatedly mentioned is don't trust the cutoff switch! (I have seen one pole fail to disconnect because it rusted out). A plug, when removed, can always be trusted! I demanded the same for a bandsaw at work.

    Yeah, its against code, and no creditable installer or company would do that. Key word there is creditable.

    That is 100% against NEC and would fail an inspection. I have never seen an disconnect fail. The approved disconnects actually remove the contacts from the box creating a visible air gap.

    I've got to agree with you 110% as I noticed many of the things of you pointed out. I like this site for "ideas" but that sad fact is many people either give wrong instructions that could cause someone to damage their equipment, items, etc. or simply give instructions that are against code, or flat out dangerous. I notice this especially on projects that have electricity, building something that uses electricity, or adding extra electricity to something, etc. etc. Maye one day I'll have the time to go through everything electrical on this site that's done wrong, and do a write up with the correct way to do it. LOL!

    As I mention in mu 'ible I just use water and no corrosive cleaners. This is intended to be a basic cleaning that most people can do at home to improve their cooling output and not as instructions on a full professional service. I appreciate your comment and I'd love to see an instructable on how to do a full service. As for my choice of tools; I prefer a ratchet to a flat head because of convenience and a rubber mallet is very handy when trying to get the top back on on 'Lid' style units. If you do not need a mallet then of course thats fine. I just happened to find it useful so i mentioned it as an optional addition.