[DML] Air Conditioning

["David Teitelbaum" <jtrealty@xxxxxxxxxxx>]

It is that time of the year again when we try the A/C and it doesn't
work! I got several off-list e-mails this week and in the interest of
the entire list I will repeat several things. A/C work requires
expensive, specialized tools. You MUST evacuate the system to a hard
vacuum to remove ALL air (non-condensible gases)and moisture. R-12 is
hard to come by and it is a crime to waste it (literaly). That said
there is still some things a DIYer can do. You can get the parts you
need. You can pressure-test the system by using compressed air
(assuming there is no pressure in the system so you are not wasting
any refrigerent). You can remove and replace parts in preparation for
the A/C shop assuming you can make prior arrangements. You can
electrically test the system and repair as necessary ahead of time.
You should insist that the shop checks the oil fill and even replaces
it. They should replace the service valve cores and any missing caps.
They should pressure-test, sweep charge, and then vacuum for at least
1/2 hour, an hour is better. Fill with a measured charge and
performance test, adjusting the low pressure switch if needed. If the
system has ben dead for a long time you "should" replace the dryer.
One of the more common parts to fail besides the service valve cores
to slowly leak is the discharge hose. It is the hose that runs from
the compressor to the condensor core in front of the radiator. On A/C
systems the rule is to do as little and to disturb as little of the
system as you can. If a joint is not leaking it is not considered good
practice to replace the seal "just because". The chances of damaging
the joint are too high. In general you have to be VERY CAREFUL with
the fittings. You wind up using large wrenches because the fittings
are big but you are working with aluminum so it can twist and break
very easily.
David Teitelbaum
vin 10757







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