I am using a Highway 22 system, which as I understand it comes with a 40 amp fan relay (or fuel pump...but I have it wired to use for the fan).
I had sent an email to the fan mfgr asking what the 3 wires from the fan are for. (No docs came with the fan). Below is their reply:
What kind of relay system are you using?
The gray and brown are hot wires (2 speed motor) and black is ground that needs to go directly to the battery (core support and frame are not good ground).
Most of my customers tie the 2 hot wires and use it as an all time high speed with my FR-70 wiring kit and temp. switch. You would need a 70 amp relay, 10 gauge wires and a fuse or circuit breaker of no more than 40A.
That information makes me uncertain about using the relay in the Highway 22. Can I just replace the 40 amp relay in it with a 70? What about the circuit breaker comment?
BTW...I do plan to wire in a trinary switch.