On a recent trip I ran into difficulties with my fan controller. I have a three fan set up with two fans wired to one lead and the third on its own. The current control module is fused at 30 amps. It controls the fans by a potentiometer (?) and a relay. The fans are rated at a draw of 5 amps each “at full speed". The controller I want to switch to is rated at 40 amps “at start-up”.

What is an estimate for how much amperage these fans draw at start-up? Even though the fan amp draw may/will be greater than 5 amps per fan, I think I am safely under 40 amps at the start and under 28 amps continuously.

Am I right?

Thanks for any help!

I have similar setup with 3 spal fans. I originally had them wired to a single 30 amp relay which melted. The fans were rated a little less than 7 amps each so it seemed like it would be Ok but running amps is not the same as starting amps and if the fans cycle too quickly well...

I have all three on their own relay now. Overkill maybe but it's not melting anymore.

I think the controller I have been using is undersized electrically. Over time the unit shoes signs of being overheated. The controller I am looking at is rated at 40 amps. I am hoping this will make a difference.

You could have the controller just control multiple relays that way you spread out the load. What I did was use the circuit that ran the a/c fan to trigger the 3 relays. Low amps for the control circuit and only the relays see the load.

I like that idea. It would allow me to isolate each fine and not put such a load on the controller. Thanks!

Glad I could help.

If you still have a working a/c you could split them up like I did and have only one fan go on with the a/c.