It's a "pressure sensor" or "limit switch".
> 2) the unit is bad and needs replacing. What should I ask for? Does anyone
> on the list have one? How much?
Ask for an "A/C pressure switch"; Peugeot has their own name for it,
something like "tri-switch." It contains two pressure sensors, and it
prevents the compressor clutch from engaging when system pressure is too
low or too high. If you know its pinout (see wiring diagram), you can find
out what it is telling your A/C system by testing it with an ohmmeter.
> 3)Any recommendations?
Either you have too much or not enough refrigerant, or the switch is bad.
So much for useless advice :-) .
If the A/C system hasn't been serviced recently, you probably don't have
too much refrigerant :-) . That suggests that you have a slow refrigerant
leak, or your switch is "crying wolf" (signaling a nonexistent problem).
I'm not aware that these switches are prone to failure, so if the A/C
hasn't been disturbed in a long time, you most likely lost some
refrigerant. The official way to diagnose this is to attach a standard
refrigeration gauge set (hi/lo gauges) to your A/C system, and see what
pressures you have. If your pressures are O.K., you need a switch; if your
pressures are low, you have a leak, and you need it fixed, plus more
refrigerant. You already know how to deal with that.
The switch screws onto a schrader-type valve stem; when the switch comes
off, what's underneath looks like a tire valve. You can change it
yourself. The switch unscrews, and the schrader valve inside closes and
keeps the refrigerant in the system. Well, mostly; you'll lose a tiny bit
of refrigerant when you take the pressure sensor off.
You can either 1) diagnose the problem with refrigeration gauges or 2)
try replacing the switch and "see if it works." The most likely cause,
IMHO, is a slow leak. If I'm right, replacing the switch won't help.
If you're a really crazy do-it-yourselfer, you can get the license (it's
US$20 and *really* trivial), buy the tools and refrigerant, and fix it
yourself. I have. (You really can use an old refrigerator compressor as a
vacuum pump.) However, I would not recommend this to ordinary, sane
people. If you're truly insan-, um, "interested," start by studying
www.autofrost.com :-) .
> Thanks
You're welcome.
Good Luck,
stuart hastings