Tip: The "short-cycling"
Air Conditioner
and other things to keep your eye on!
If your AC is cycling on and off in hot weather and not cooling down your rig,
it's time to look at the
condenser coil and possibly give it a good cleaning.
Here's a typical example of a clogged condenser coil. I installed this new
Coleman 13,550 BTU in the
Spring of 2004. That Summer it performed admirably and I was quite pleased with
it's performance.
When the next Summer of 2005 came around, I noticed on the hottest days, my
rig wasn't being cooled
as well as it had been the Summer before and the inside temp. was reaching into
the upper 80's.
The actual symptom was, when the AC was first turned on earlier in the day,
it seemed to run fine and
cooled well.. As the day grew warmer (into the 90's), the compressor would shut
down even though the
thermostat was still calling for cooling. The fan would continue to run as expected,
but didn't cool my rig.
After a short time, probably 1 to 3 minutes later, the compressor would start
up again and it would again
begin to cool down. The problem here was that the compressor was cycling off
for more time than it would
run. This led to the rig slowly heating up inside because the compressor wouldn't
stay on long enough to do
any good.
In normal operation, the compressor should come on and stay on until the thermostat
setting is satisified.
The compressor should not cycle off and on unless it's because the thermostat
is telling it to do so.
I decided to go up on the roof to take a look and this is what I found. It
only took one year for this
'bio-funk' to accumulate, so guess what that means! I'll be up there every Spring
to clean out that coil
and while I'm up there, I'll be checking the fastening screws, inspecting wiring
and looking for anything
out of the ordinary while I have the lid off!
You can see here just how much stuff was clogging the coil after I cleaned
it. Also, the two tools I used to
do the job. The whole job took about 20 minutes from start to finish.
( That black thing in the lower right corner of the pic is the camera strap.)
Here's another view after cleaning. The fins were actually much cleaner looking
than these pics show.
I hadn't used the flash when I took the pics, so I had to enhance them a bit
with my InfranView to get a
touch more detail out of them.
Here's a shot of the shroud fastening screws. As you can see, they are all
showing signs of corrosion.
These screws are stainless and I'm thinking they are becoming corroded because
of an electrolysis effect
between them and the fasteners they screw into which hold the shroud in place.
They will get replaced
this coming Spring while I'm up there to clean the condenser again. You DON'T
want these screws to
become frozen to their mating fastener or you'll be up there with a Dremmel
Tool cutting them off and having
to deal with pem-nuts that are probably not the easiest thing to find around
here.
After cleaning and replacing the shroud, the AC worked perfectly again and
kept my cab-over at a pleasant
75 degrees in the hottest parts of 110 degree days. I sleep during the day up
there when the outside temp. is
at it's hottest during the day, so this is not just a luxury for me, it's a
necessity, at least until I get a day job!
Thanks for looking,
YoDude
01.04.05