I did an electric fan swap from a 940 into my 1990 740 GLE 16V, using the big radiator, and the stock Volvo relay. This is a very easy swap. The relay has two wires coming out of the middle which are grounds used by the 940 ecu to turn the fan on, one at high speed and one at low speed. I hooked these wires to temp sensors, one in the radiator and one in the lower radiator hose, like a 240 turbo. The low speed wire is on the lower radiator hose. On each sensor, i took the other connector and sent it to ground. Main power wired to the battery+, Done! Now the fan turns on if either sensor reaches it's temp setting and completes the ground circuit.
Much quieter car now- and it runs cooler with the big radiator. Anybody with an engine driven fan should do this swap.
Also put a late 940 intercooler in at the same time. Wonder why?