Last year, I fitted A/C to my 1991 1.4 Fiat Tipo, with the larger radiator and condenser from a 1.6 model, trinary switch added. The 2 wire fan was made to run at 2 speeds using 2 relays, a resistor and a three wire, 2 temp thermal radiator switch which are not currently fitted.
No wiring diagram is available for this setup, but I've drawn a diagram of the wiring taken from the donor car with two (Earth?) wires unaccounted for.
Until wiring sorted, fan cuts in at high speed only, to cool A/C condenser and or hot engine coolant.
I'd like the fan to work on slow speed as well.

 

Are you asking for help or just letting "us" know it can be done.? LOL

 

Don't think you will accomplish 2 speeds from a single speed 2 wire fan. Why not just turn it on with either input?

 

The old Buick GN's had a "two speed" fan. Basically two hots to the same terminal with one running thru a big heat-sink resistor, one ground wire...

 

Better to use a PWM controller. Will allow the fan to run at any speed you want. I have something similar on my fuel pump

https://www.summitracing.com/parts/d...jpORoC6mHw_wcB

 

Depends on the fan you're using.

Here are two setups I've successfully wired on two different style s of 2-speed fans.

You can run a 2-relay, 2-speed setup with something like the Taurus fan where low speed activates 1 relay and high speed activates another relay. You just have to tune the PCM so that low speed is off when high speed is on.

Or you can run a 2-relay, 2-speed setup on a Derale fan where low speed activates 1 relay and high speed activates both relays. This is also adjusted via PCM tuning (This is the setup I'm currently running in my LS swapped Wagoneer and my friend's LS swapped Wrangler)