"Hi Hancock, the rotating roof fans are a nice feature on these K-Line engines. I did not tie the power for the fans into the EER board because I was not sure how much current they drew. For my setup 18VAC goes into a small circuit board for the fans (mounted on the shell) and then DC voltage come out for the small fan motor with pulley. Instead of connecting it to the EER board I took the easy way out and connected the input for the small circuit board to the red pick up wire and the black common wire. The down side is the fans rotate anytime the track has power."
I can't recommend this for all cases because I don't know if it would cause any sort of electrical feedback issue (it hasn't in my experience), but I have wired DC power supply circuit boards to the motor inputs of my TMCC/ERR-equipped diesels so that the power comes on only when the motor is running. The motors for these roof fan features appear to me to be smoke unit fan motors and so they draw something like 5 VDC. The DC power source I have used is a very small board that comes from Ngineering (designed for LED simulator modules) which has an onboard rectifier so can be hooked up to an AC input although the power to the motors is DC.
