Outer Limits 4x4 Board

I've got a 1990 Ford Maverick> Now the air-con is nice and cold and still runs on the old gas. My question is in relation to the 4 wires which come out of the reciever/dryer. The relay for the elec air-con fan relies on two of these wires to earth the circuit therefore connecting batt straight to fan. Now this switch doesn't seem to be working as when i bypass these two wires and earth it the fan kicks in, i'm not game to unscrew switch because i will loose the gas i suspect. Does anyone know what might be the problem or how crucial is it that this electric fan works anyway.

Thanks

Temp switch, brings in fan when refrigerant gets to certain temp.
I wired my fan to come on thru a relay when aircon clutch on so it always ran with aircon. Helped a lot in slow bush work.
Leave switch in its fitting.

Bazzle