You've already checked the fuse, that's always the first thing.

Jumping the switch on the thermostat housing doesn't prove an a/c fault at that switch should only work at ~105degC and will turn the fan on full speed,not low speed which is what the a/c turns on.

Is your A/C cold when driving? If it isn't then you may not have enough gas in the system to trip the pressure switch to turn the fans on. The fans shouldn't run all the time when the a/c is on.

I think your model has 2 speed fans. Check the fuse in the relay for the aux fans. Also check the balast resistor for the aux fans, they burn out eventually.

Get back to us with what you find.

__________________
Alex.

MB Tech
Sydney, Australia
Volvo 122S
W201 190D 2.5 manual
W202 C240
W203 C32