We have a Jenn-Air dual fuel downdraft range purchased in 1992. Still works well but switch that controls fan and oven light on top of stove broke. Part is no longer available but they tell me that I can use a single switch to operate fan only. My problem is which wires to use. Old switch had 4 spade terminals (male), Blue, Red, White and Brown ( both white and brown had 2 wires into single spade terminal.
Can you tell me which wires to connect to make fan work? Oven light will still work from door switch.

To make the fan work connect the red and blue wires. For the light it is the white and brown wires.

I had the same issue with the fan and searching for years I never came across another switch like it. Then I finally ordered double pole double throw rocker switch from Galco part 54-052-NTE. It is a much bigger switch, but I just hogged out the metal in the cover with a dremel and a bit that looks like a milling bit. After the hole was made large enough, I installed the switch and put back the bracket that holds the cover in place with the 2 push down tabs. I re-installed the switch but first the 2 spade connectors for the brown and white wires had to be replaced to the larger ones so that they would attach to the new switch. Now everything is operational again. You need the double pole double throw switch to isolate the 2 circuits. A SPDT won't work.

Good luck.