A typical A/C service/checkup call will typically include the following:
-Freon Level check
And a few other items, depending on the company. I’m going to show how to do what I consider the most important part of the service – checking and cleaning the coils.
If your coils are dirty or clogged, there will be reduced airflow and you may notice the unit freezing up regularly.
The main cause for the evaporator coil to be clogged is the lack of an air filter, or one that hasn’t been changed and is allowing dust through. Anything floating in the air that isn’t caught in the filter will stick in the coils, and cleaning the coil is a lot harder than changing an air filter.
Start be finding the indoor unit (Central Heat/A/C). It will probably look something like the picture below and will be found in a basement/attic/crawl space/garage or even a closet. Note that some units are all one piece, but I’ve been seeing those less and less lately.
This picture doesn’t show the whole thing, but gives you a good idea.
Before you start – Make sure to cut all power to the unit as a safety precaution. While not entirely necessary, I also fin it easier to clean the coil without the fan running.
Now take off the panel(s) that cover both coils. The coils can be found with the help of the copper tubes that will go into the unit. These lines carry refrigerant and connect directly to the coils. The lines can be seen in the top right corner of the picture above.
One the panels are off and the coils visible, the fun begins. I recommend using a condenser/evaporator coil cleaner which can be purchased in an aerosol can at most hardware or refrigeration supply stores. Start by following the directions on the can – if the result is not satisfactory, then get a soft bristled brush and start scrubbing (being careful not to bend any of the thin metal fins).
The ends of the coils.
The top of a partially cleaned coil – you can see the shiny silver part up front and the back is still caked in dust.
This coil has just been cleaned.
This is the back side of both coils. Rarely will this part be dirty, because they typically clog long before the dust/dirt reaches this side. Notice the bubbles appearing – that’s a good sign. It means the liberal amounts of cleaner applied to the other side have finally penetrated through.
That’s mostly it – Here’s a picture of the brush I use for cleaning them-it’s just a soft bristled cleaning brush taped to a rod to make it easier to stick into the unit:
Many units have a place up here to add a second air filter. If yours does, now is an ideal time to install/replace it.
When you finish and put the panels back on, check for area where they don’t seal together and allow air into the unit. That can cause problems with freezing down the road. If you can’t get everything to seal properly, just attach it and use duct tape to seal any gaps. This is probably the closest use you will ever see the “duct tape”s original intended purpose. I also choose to close the unit back up with self tapping metal screws instead of the ones I removed, as I can get as good or better seal with them and they’re more convenient for me to replace when lost.
One last thing on the indoor coils- the stuff in this picture stays in the attic all the time. That saves me from hunting or having to purchase tape/cleaner halfway through the job.
To clean the outside coils is much easier and really never needs done. Most people only choose the clean them so they stay shiny, so I won’t explain in detail how to do it. In short, remove any panels covering the coil, spray cleaner on and let soak according to directions, and hose the coils off.
While I’m at it, here’s a way I found to store extra air filters: