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From: heffner@bsdpkh.UUCP (Paul K Heffner)
Newsgroups: net.auto.tech
Subject: Re: air conditioning advice
Message-ID: <116@bsdpkh.UUCP>
Date: Thu, 24-Oct-85 22:44:16 EDT
Article-I.D.: bsdpkh.116
Posted: Thu Oct 24 22:44:16 1985
Date-Received: Sat, 26-Oct-85 04:29:29 EDT
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> >I have also heard of a special propane torch head which has an attachment
> >for a hose, used for the purpose of sniffing freon.....
> 
> Aieeee!! This is something you don't want to do! The combustion products
> from freon are quite toxic. All that fluorinated and chlorinated stuff is
> bad news when you burn it.
> 

My father runs an A/C-Refrigeration repair buisness (1-man) and I have
been literally been fixing the stuff as long as memory serves. (It
broke the old boy's heart when I became a bit flipper...)
I've been following the A/C repair discussions with interest and I hope
I can add some useful input. Scott Wilde was technically correct regarding
the burning of F-12 in Propane as it forms Phosgene gas which is rather
noxious. The leak detector device under discussion however, is not likely
to produce enough (given a reasonably small freon leak as the one under 
discussion) to do much more than make you sneeze. As an aside, it has only
been within the last decade that propane torches have taken off for general
refrigeration repair use. Before that it was always acetyline torches for
soldering/leak detecting which never seemed to produce any noticable smell.

Regarding the use dye to find the leak, DuPont was marketing F-12 with
an additive called (I believe) Dyetel. We found this far more desirable
than a dye additive as the additive was suspected to corrode the copper
fittings. Actually the dyes very rarely ever were of use as the freon
has a tendency (spraying out under high pressure) to just dye up the whole
general area and leave a mess. We had lots of luck, however, with the
simplest and cheapest detector of all: Bubbles!! (Childrens soap bubbles)

Bring the system up to a reasonable pressure (50-100 psi if you have 
gauges) and use a small brush to soak the stuff on all the joints you
suspect. Even the smallest leak will produce noticable bubbles. Use a 
small mirror to peek behind the joints as the bubbles will appear usually
at one side of the joint.

Since you have been adding freon for years and not adding any oil, there's
a good chance the shaft seal of the compressor is your (primary) leak as
the system oil recirculates through the system and will escape along with
a leak. Refrigeration oils are specially formulated for low wax and moisture
content. A good mechanic will evacuate the system to remove any air which
might have migrated into the system. An extremely low vacuum on your system
causes any moisture to vaporize and be drawn out. He can also ( If well
equipped) replace the oil (can require a special pump)

Sorry to ramble on so, hope this helps....

						Paul Heffner
					{ihnp4,akgua}!bsdpkh!heffner