From: John De Armond
Newsgroups: rec.autos.tech
Subject: Re: AC leak
Date: Fri, 25 May 2001 23:32:36 -0400

Robert wrote:

> Yes it does, the shrader valve should not leak at all. The valve is easily
> replaced but any remaining freon should be evacuated first. Of course it
> will have to be evacuated and charged again afterwards. It should also be
> checked again for leaks.

No, the system does not have to be pumped down to change a bad
shraeder valve core.  All that is required is a core removal tool
and about 10 minutes.  Here is a picture of mine:

The operation is simple.  The device is attached to the shraeder
valve. The core removal rod is pushed down on the core where it
snaps in place.  The knob on top is turned counter-clockwise to
remove the core.  The removal rod is withdrawn until it hits the
stop.  The isolation valve on the right is shut.  This isolated the
space containing the core from the system.  The compression nut is
unscrewed and the rod assembly is removed.  The defective core is
removed from the rod and a good one is snapped back in.  The
assembly is inserted back in the tool and the compression nut is
threaded but not tightened.  Crack the isolation valve for a second
to remove air from the tool. Tighten the compression nut.  Open the
isolation valve.  Push the rod down until the new core contacts the
threads in the fitting.  Tighten it down.  Remove the tool.  Check
for leaks.

Easy as that.  Replacement can be done faster than it takes to read
the procedure.

If one needs to add or withdraw refrigerant, one can do that while
the core is out through the gas port.  Leaving the shraeder core out
gives much better flow, very important for evacuating the system.

Any refrigeration mechanic worth his salt will have one of these.  I
got mine from Johnstone Supply (a national chain HVAC supplier) for
about $30.  The manufacturer is:

C&D Valve Mfg. Co.
Box 13250
Oklahoma, OK 73113
800 654 9233

From: John De Armond
Newsgroups: rec.autos.tech
Subject: Re: AC leak
Date: Sat, 26 May 2001 04:03:19 -0400

AC/DCdude17 wrote:

>     Do you happen to know any auto HVAC shop whose willing to do the valve
> replacement, then top off the lost refrigerant to the point forming doesn't
> occur in check window?

Since I have no idea where in the whole world you live, the answer
is no.  If you happened to be in Cleveland, TN, I could do it for
you.

>I got ripped big time by a dealer.

Mistake #1.  Taking non-warranty work to a dealer.  They have the
highest labor rates and they're under the most restrictive work
rules.

> They pumped down the whole system, filled it with specified capacity of
> the system and charged me for the FULL capacity.  All I needed was top
> off.

That's the official procedure - recover the old refrigerant and
reload the system by weight of refrigerant.  And thanks to the
lobbying effort of the service industry PAC (MACS), it is either
illegal or in a grey area to reuse the recovered refrigerant.  (One
can legally reuse it but only if it is recovered in a separate
container and only if it is put back in the same system.  That's not
going to happen in a busy dealership.) I imagine the dealership is
required, if not by the factory then by liability concerns, to
follow the official procedures.  Independent shops are not.  Just
think of how many different petty chickenshit things people sue
dealers and manufacturers for, trying to get something for nothing
and then you'll understand why the dealer has the policy.

Like any independent mechanic, I can use whatever technique I
believe offers the customer the best deal.  In this case, that would
be to replace the valve core and then top the system off.  If the
system was empty, I'd evacuate it and then charge by weight using
the specification for your individual car.  But I can also charge
using the sight glass.  And if you don't have one, I can charge
using my ultrasonic stethoscope to listen for the cessation of
bubbling in the expansion device.

You really have only a few options.  You can go to the dealer and
pay the price.  You can find a good independent mechanic.  That
takes a lot of work and you may have to find a different mechanic
for different kinds of problems.  Or you can get a green card so you
can buy freon, learn about refrigeration (or whatever system is
giving problems) and do it yourself.  The latter is the only way
you'll ever really know it is done right.

John