"88accord170+" <brianedearden@hotmail.com> wrote in message
news:1154454293.808296.209670@b28g2000cwb.googlegr oups.com...
> After I had the AC retrofitted to r134 and charged, a year later it
> doesn't work. Alsoo have problems with the fan switch. i learned that a
> loss of pressure(below a certain point, in the system) will disable the
> compressor from engaging(for those who were wondering) it does that to
> "protect" itself. All i know is that i measure high pressure when the
> compressor is off, and I measure low pressure when it's on. This seems
> backwards to me. could i have a blockage, how can i remove one. also
> when i added refrig, it did not seem to last more than a month +or-.
> PLEASE HELP, MY CAR IS COOKING ME ALIVE!
>
As the others say, it has a leak. The reason the pressure drops so much is
that there isn't enough refrigerant available to flood the evaporator.
Without refrigerant to evaporate the compressor pulls a vacuum on the
evaporator. Usually that causes the compressor to "short-cycle" - run a
couple seconds, release for a couple seconds, over and over.

With anything resembling a proper charge the low side port (where you are
connected, I'm sure) will read somewhere above atmospheric pressure while
the compressor is running. With the compressor off, the whole system will
read a higher pressure if there is even an ounce of refrigerant; in each
case the pressure corresponds to the vapor pressure of R-134a at the
temperature of the part you are measuring.

Bottom line - you need to take this to a pro at this point. You definitely
have a leak - it may be where it is impractical to do a "real" repair, like
the evaporator, or it may be a seal or hose. If it's the evaporator ask
about adding a sealant. Pros hate the stuff because it can gum up other
things and/or not work, but if you accept it as a gamble.... Keep a good
thought that it's a hose or seal. When the leak is fixed and the proper
charge added you should stop cooking.

Mike