Gentlemen, I have not been able to locate any electronic control modules in my system. As Mike stated, my system is a mechanical loop that runs from hydraulic pump on motor, to fan motor, and then into switching valve mounted on fan motor. Out of switch valve it then runs to wax valve, then back to fan motor, then returns to tank reservoir. I am also thinking that switch valve may not be operating properly. Another thought is that the #4 lines from switch valve to wax valve and then back are not big enough to relieve pressure to slow down fan. Am thinking about replacing lines with #6 line to get more flow away from switching valve. Regarding switch valve, I have not been able to locate any info. All I can find is the complete fan motor assembly with switch valve installed. I would think that the switch valve would have a rebuild kit, but so far have been unable to locate one. My Saur Danfoss fan motor # 551-1-01303-210 is available, but would be nice to locate a rebuild kit, as complete fan motor assembly is $1,400.00. Again, thanks for any help, Frank.