I have a couple of small through the wall ac units. They are the 9000
btu single room style bought a discount type stores. Athought I clean
the manufacturers filter routinely, it looks like quite a bit of
dirt/dust is building up on the radiator? (coil?) directly behind the
filter on the return air side. I am temped to blow it out with air,
but that strikes me a maybe just driving it deeper. Is there a way to
do this without removing the unit?
You can clean the AC fins using compressed air if:
1) You use reverse air flow - shooting compressed air
in from the clean side. If you can't get access to
reverse flush, then you can experiement with hitting
the fins at a very oblique angle - you are hitting
the fins sideways. This isn't as effective, but better
2) You don't smash the fins with high psi air.
I use a special kind of blow gun with produces
a very high volume of air with a much reduced
psi. Available at Harbor Freight and other outlets
for compressor items. The barrel of the air gun
has openings at the base to entrain ambient air
(suck in outside air) as the compressed air moves
through the barrel. This entrained air greatly increases
the volume of air and also slows down the airflow.
3) You lightly loosen the debris carefully with an old
soft toothbrush or some other very soft brush.
Obviously, you should brush with the fin direction
and not against it.
I'd suggest picking up an inexpensive fin straightening
tool (also available at Harbor Freight). Have it handy to
touch up any areas where you accidentally smash the
fins. You can also straighten them with an old knife,
but thats pretty slow.
Blowing it out with compressed air is better than no service. but, if you
want it really clean, you need to disassemble the unit and use professional
I've cleaned out a LOT of window or wall units. Probably over 100 of them --
compressed air doesnt do it.
I used to unplug the A/C unit and use a hand spray bottle filled with water.
Holding the spray bottle 1" away from the fins - I would spray the fins
starting at the top & working my way down. My theory was that the water
would flush any dirt off the fins & there was no problem with the small
amount of water used as the A/C units are designed to drain condensed water
off the fins to the outside (provided it is installed correctly with a
slight slope to the outside).
I would do the same to the exterior fins - but in that case using a garden
hose. Amazing how much gunk collects on the fins over a season.
Let it sit for 1/2 hour to ensure the water is drained and away you go...
I also do this to my central air outside condenser unit each year - making
sure I don't have so much water pressure that it would deform the fins..
Last spring, after much flushing of the fins I tried spraying the fins with
some 'Siege' - which is a air filter degreaser chemical. MAN - there was
tons of dirt that came off when I again sprayed the fins. I guess the dirt
is not dislodged by just water alone. Because of this - it might help you
to use a small (very small) amount of dish soap (or Siege if you have it) in
the water you spray on the coils. Then rinse with clean water (you don't
want your A/C blowing bubbles afterall.
By the way - Siege is also great for any type of cleaning you need to do
around the house (and no, I'm not a salesperson for it - just a BIG fan of
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