From: John De Armond
Newsgroups: rec.outdoors.rv-travel
Subject: Re: Air Conditioner Compressor question???
Date: Thu, 31 May 2001 12:37:52 -0400

LOCOMOTIVE2506 wrote:

> As noted, there won't be any service fittings. Take it to an AC person that
> knows what they are doing. They will install new service fittings on the
> piping, evacuate it, refill the freon and check for leaks with a very sensitive
> Freon sniffer. Almost guaranteed they will find a small leak around the heat
> exchanger at one of the solder fittings. Since the compressor is running but
> not pulling a full electrical load then most likely the compressor is OK and
> youv'e just developed a leak in the Freon system. A new compressor can get real
> spendy, been there done that.

To add to this, make sure the service guy does NOT try to use a
"saddle valve" type of service fitting.  This device is similar to
the piercing valve used to tap water lines to get a little water for
an ice machine hookup.  It clamps around the refrigerant line and a
little sharp bolt punches a hole in the line.  It works at far as
that.  The problem is, the valve never seals perfectly to the pipe
and so ALWAYs leaks, if not immediately, then after a number of
expansion/contraction cycles.  A lot of less than honest service
techs use them because they know that the valve will guarantee an
annual service call to recharge the system.

The proper way to install a service fitting involves using a saddle
valve to tap the process fitting (a stubbed off tube sticking out
the side of the compressor. to remove the remaining refrigerant.
Then the end of the process tube is cut off and a pigtail shraeder
valve is hard soldered to the tube.  The system is then pumped to a
vacuum and re-charged.  This type of valve, which comes with a cap
that positively seals it off when not in use, will be as hermetic as
the original system.

There is another tap, not commonly used on small systems because of
the labor, called a "solder saddle valve".  This valve works similar
to the saddle valve above but is silver-soldered in place instead of
clamping.  This valve works as well as the pigtail shraeder valve
but it requires a lot of labor to install properly.  Because a main
refrigerant line must be heated red hot to solder the valve in
place, the system must be pumped down and then filled with an inert
gas (argon, nitrogen, even CO2) before soldering.  The inert gas
prevents the inside of the pipe from oxidizing and throwing off
scale particles.  If the freon isn't removed, it will break down
under the heat, yielding hydrofluoric and hydrochloric acids,
neither of which contribute to long system life.  The only time I
used these valves is on the rare system that doesn't have a process
tube.

This sounds much more complicated than it is.  The big thing is to
make sure the service guy doesn't try to use a saddle valve.  If he
doesn't know any better, find another tech.

John