> From:    Larry Hinshaw <LHinshaw@EARTHLINK.NET>
> Date:    Fri, 6 Apr 2007 18:23:06 -0400
>
> My son and I are thinking of doing [an A/C system replacement]
> ourselves.... he is a novice auto tech and we have the Bentley manual.
> Can this be done in our driveway or is it best to have a pro do it?

IMHO, you need a pro to start and finish, but the middle you can do
yourself.  The "start" part is to have a shop suck the existing
refrigerant out of the system.  This is partially because it's illegal
to vent it yourself, and partially because you can give yourself a
really nice frostbite if you manage to vent it onto yourself.

Then, it becomes a patented "installation is the reverse of removal"
job.  Some tips: A lot of the fittings are aluminum or otherwise soft;
get the correct fixed-size wrench instead of using an adjustable wrench.
Flare-nut wrenches, that grip the fitting on four sides instead of two,
work well.  Keep crud out of the connections - don't let the hose ends
drag on the ground and so on.  Try to keep the system "closed" as much
as you can - nothing earth shattering will happen in the time it takes
you to unscrew the old hose and screw the new one on, but if you knock
off for lunch or for overnight, you might plug up any open lines (rubber
corks) until you get back to it.

There is some oil that circulates along with the refrigerant and the oil
has to be compatible with the refrigerant.  The new compressor may or
may not come with oil in it; if it has oil there should be a tag that
says what kind it is.  In these latter days it's probably the right kind
of oil for R-134a, but check anyway... if it's not the right stuff, you
might have to drain it out of the new compressor and maybe put in a
little of the correct stuff before you install the compressor.

The "finish" part is to go back to the shop to have them pull a vacuum
on the system.  This may suck out some of the crud and will let any
water in the system boil off.  Then they will fill it with refrigerant
and oil and check for leaks.

Haynes (among others) publish some non-vehicle-specific manuals to go
along with their other manuals.  There is one on welding, one on
auto electrical systems, etc.  I suspect there is one on A/C and
heating and it might be a useful source of additional information.

Matt Roberds