Thanks HeatMan, for those clarifications and corrections.

"HeatMan" wrote in message
link.net...
Not too bad. You have the basics right.

But....

"Kelly Jones" wrote in message
...
I can't stand it....


I know how it must feel - overwhelmed by the technology that goes into
the
modern house. But service contracts (in my humble opinion) are just
get-rich-quick schemes perpetrated by the unsruculus on the ignorant.
You
can't do anything about the unscrupulus, but you CAN do something about
the
"ignorant".

There are many sources of information today about the systems in a
typical
house. You should have no problem finding the information you need to
evaluate the problems you may encounter with any particular home system.
Whether you choose to do the repair work yourself or contract it out is
of
little consequence and is a matter of personal taste. But you should be
prepared to deal with any system failure in your house. To do that, it
only
takes a little knowledege. To wit:

Air conditioning units (and heat exchangers) are simply oversized
refridgerators and work on the following principles:
Heat is pumped from one location to another by applying work. We know
that
it takes a lot of heat to convert a liquid to a gas. If we allow a
liquid
substance to rapidly expand (increase in volume) then the substance will
absorb a lot of heat from the surroundings. If we then get rid of the
heat
the substance will change from a gas back into a liquid and it can be
pumped.

Pretty good expalination.

The evaporator coils are the mechanism for rejecting the heat. The
overall
efficiency of the machine is related to how well we can reject heat.
Therfore we need to keep the evaporator coils as clean as possible.
Anyone
can clean the coils. Just don't damage them.

Wrong. Right idea, but wrong part. The condenser coils are what rejects
the heat. If you read the paragraph above this last response, you see
what
I mean. As a liquid boils off, it evaporates. Real close, good thoughts.

Further, the compressor (which pumps the liquid) must be kept
operational.
Keep dust and dirt away from it. Keep the refrigerant charged so it
doesn't
run all the time, and keep watch for any evidence of leakage at the
shaft
or
the fluid connections.

Still close. The compressor is actually a vapor pump and it's the big
black
(usually) thing inside the outside unit. It takes the low pressure, low
temp refrigerant and turns it into a high pressure, high temp refrigerant.
The condensr coil 'condenses' it from the vapor to the liquid. Pretty
good!

If you are not comfortable doing the work yourself, that's OK, just make
sure you get a reputable service technition. But my main advice is to
try
to understand how the unit works so you know what can go wromng and what
you
are paying the service technition for. If you can do that you won't
need
to
pay for a "warranty".

Amen!

You looking for work? You've got a better grasp of the refrigeration
circuit than some techs I know....

There are a few tasks a HO can do. Change the filters with a good quality
filter, keep the area around the condenser clear of bushes (Manufacturers
say 36", I think 18" is enough). Keep the grass clippings off the outside
unit. Once a year, use a shop vac to clear the condensate lines. (Ask
your
tech how to do this) These things will save you money in the long run.