Checking vacuum operated valves (Was: Auto-Temp help needed)

["Dick Benjamin" <DickB@xxxxxxxxx>]

I'm not sure which vacuum check valves you are referring to, can you be more
specific?

There are check valves to stop air from moving in one direction only - these
are checked by plugging them into a source of vacuum first one way and then
the other way.  One way you will feel vacuum at the open end, the other way
you will not, if the valve is working right.  These do not ordinarily fail,
if the system has been well maintained and is not contaminated with
particulate matter - they are very simple devices.

There are also the switch valves, which operate the master power switch and
the compressor switch - these are the valves with wires going to them.
These are checked by applying vacuum from a measured source (one has a
threshold of 10" Hg and the other has a threshold of 2" Hg) and verifying
that you have continuity between the two electrical contacts when the vacuum
is present in the right degree.

You can temporarily bypass the latter two valves by making up a jumper to
connect the two wires together.  This will make the system think the vacuum
is up to threshold, and turn on the system and the compressor.

Dick Benjamin
----- Original Message -----
From: Dennis & Mary Ann Martin <marti595@xxxxxxxxxxxxx>
To: <mailing-list@xxxxxxxxxxxxxxxx>
Sent: Monday, August 26, 2002 9:10 PM
Subject: IML: Auto-Temp help needed


HI:
I am new to this forum.  Can anyone tell me if they have tested the vacuum
check valves in a 1968 or similar Imperial Auto Temp system?  I have printed
out the manuals from the Web site, and my friend (owner of the Imperial) has
the shop manual.  I would like any one with personal repair experience on
this system to contact me.  My friend and I have each invested 30 or more
hours in his 68 Imp. and it still full of surprises and is also not working.
(Needless to say, we are not professionals at this!).

Sincerely, Dennis Martin