The thermal switch consists of 2 wires going into the opposite side of the compressor that the clutch is on. From Volvospeed:
bypass the a/c thermal switch. Took me a while to find it, and even when i did find it, i was nervous about cutting it, afraid i was going to break something... but i said what the hell, my a/c is already broken anyway, lol.

it was kind of tough for my big hands to get to it, but i was able to snip the wires that go into the side of the compressor on the opposite side of the clutch (drivers side of the compressor, included a picture before i snipped it), and i fed the wires to the top (the wires were really really short), then took a wire nut, and tied the two together.

just by doing that, i was able to bring my a/c from working randomly, to working nearly 95% of the time.

Now, its probably a good idea to do the clutch gap fix. i havnt gotten to that yet, but i believe that is also a problem on mine (and most 850's). because my a/c still kicks out at times and blows out warm again, but only under hard acceleration (>4500rpm, or kick down initiated... sometimes it will knock it out, sometimes it wont.).

So basically, the thermal switch bypass worked wonders for me. now i can sit comfortably in stop-and-go traffic without worrying about the a/c.... it blows out ICY COLD even in the 90+ degree heat.

(picture shows the compressor from the underside of the car, which is the easiest way to get to the thermal sensor. Its the little brass-looking piece with 2 wires coming out of it)

The picture is from the under side of the car, very fuzzy, but shows the two wires going into the back of the compressor. "I" would cut the wires with just enough length left to crimp them back together again, just in case??? I like the plastic wire nut to join the two wires heading back to the car, it is much easier to join them that way.


The whole VS topic is here:
http://volvospeed.com/vs_forum/topic/76833-ac-thermal-switch/

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My name is Klaus and I am a V ♂ lv ♂ holic