On our first 70 degree day my 1995 850 turbo wagon coolant the coolant at stop lights. I had a shop install a new coolant temp sensor and thermostat and radiator hoses for good measure and asked for electrical troubleshooting on the fan not coming on. They said the fan doesn't work on low speed, will need new one at ~$500. I'm confused as to how the unit can be bad if it the high-speed still works.
I read-up here and after a bit of testing, it turns out my 5-year-old aftermarket fan only turns on with 12v applied to the high-speed female lead from the fan assy. Nothing happens when 12v is applied to other female lead instead. I suspect this means my fan assy. is still good and I should fix it, not throw it away, but I need some suggestions on where to go from here. I have yet to cut into the wiring harnesses but I can only suspect that I have a broken wire on the low-speed circuit, yes? Are there other things to consider/test? I am a beginner at this kind of thing so any advice on theory as well as test strategies would be greatly helpful. Thanks all.