Heat sensor switch on a/c - is that a ground?
 

82 240D W123
The heat sensor switch on the a/c receiver-drier that turns on the auxiliary fan to cool the a/c condenser. Does that just connect the circuit when hot and disconnect when cold? It's just a ground wire connection for the circuit (or relay circuit), isn't it?

Part number 0065451424

Jim

Looks that way to me but I'll let you decide.
https://www.startekinfo.com/StarTek/outside/12265/disc_2/program/ETM/123%20turbodiesel_2.pdf

Indeed it appears that it is a ground. Thank you for the schematic. Also appears to have the alarm rig that I asked about in the other thread. I had no idea this car had an alarm but apparently it does, although I'm not sure it has all the components.

The switch you show does indeed complete a ground, thereby activating at 100c the aux fan by way of the aux fan relay. However this switch senses engine coolant temp.

The switch that senses R12/134A temp at the receiver/dryer has 2 connectors to complete the circuit and activates at 62c the aux fan thru the same relay.

Thank you. I'm gonna have to trace these wires, I've re-rigged it twice lol.

Your car may vary. That temp sensor on my 1984 300D has a much smaller screw and 2 terminals. I recall one terminal goes to ground. It is on the coil- side of the fan relay, which you find mounted on the top inner fender driver's side (under plastic cover). A 2nd relay there actuates the AC compressor clutch.