2000 Saturn wagon. I need to recharge ac, but I can't get compressor to run
to suck in the R-134. I found what appears to be the low pressure switch
(jump switch-engage compressor, right?), but it has 3 wires. ??? Any
clues?

Thanks in advance,

TC

You need to evacuate the system first, then using a vacuum pump get all the air out. Make
sure the system holds vacuum and then put your 134 in. The vacuum will draw enough in to
start the compressor. Correct amount of 134 is 24oz. You will never know how much is in
your system if you don't start empty.

Steve

On Mon, 23 Jun 2008 06:54:38 -0400, "tom creech" <tcreech (AT) neo (DOT) rr.com> wrote:

6 North Hill Dr
Ballston Lake, NY 12019
518-877-5528

I believe that the three wire pressure switch gives a linear voltage output
proportional to pressure. goes to the BCM.
first make sure that you didn't loose oil from the sealed system. If there
is any chance of an oil leak - you will see oily coated A/C hoses or
fittings - you must replace the oil with the correct type (PAG). A UV Dye
tracer will help you find any leaks.

Generally, you take the gauge / hose adaptor and connect to the LOW side of
the compressor. Bleed out any air in the hoses by cracking the can tap valve
slightly before making connection to the car. Open the can tap and let the
R-134 feed into the system. It's a slow process as the liquid in the can has
to boil off to charge the system. Some folks are tempted to invert the can
and feed liquid instead of gas. This is really bad to do as it washes
lubricant from the compressor and can cause problems when trying to start
the compressor. Normal pressure with the compressor running is 45psi. You
should be able to get enough pressure by just connecting a can to enable the
compressor to run. May need to sit a few minutes to equalize and the
computer to register. Also try putting the selector switch to defrost which
should force the system on.

"tom creech" <tcreech (AT) neo (DOT) rr.com> wrote