Electric fans

[cycleguy55]

Sorry to revive an old thread, but I have a problem with my fans.

Setup: Dual fans (unknown manufacturer), with an adjustable controller. As I posted above, the controller drives the fans through a pair of 40 amp relays. The fans will run after I shut it off, presumably until it's cooled enough for the radiator probe to tell the controller it's cool enough. Like many of these, I have an override switch on the dash so I can cool it down a bit before getting to my destination and shutting it down. That switch has an light to indicate when the fan is running.

A couple of days ago I went to a Show and Shine and, when I got to my spot, the fans ran a LONG time - MUCH longer than they ever have to my recollection even though I had the fan override switch on as I waited for entry and access to my spot. Other than that, everything was fine. When I drove home, I turned the fan override switch on just over 1/2 mile from home. I didn't notice the fans running while driving, but they certainly ran normally once home.

Today, I ran errands and again, turned on the fan override switch for the last bit before going home, but no fans. After I shut the car off the fan override LED remained on, even with the ignition off. Hmmm.... very interesting. I've disconnected and reconnected the battery, and the LED comes back on when the battery is reconnected.

At first I thought the fans had failed - but they're dual fans and it would be a freaky coincidence if they both failed simultaneously.

Then, my thought turned to the relays but, again, dual relays. Regardless, why would the LED light up if were the relays? Unlikely.

So, my thought now is that the fan controller has failed. I haven't tested it yet, but it has power even when the car is off in order to keep the fans running, and the override switch is connected to it through the relay connections.

Does my logic compute? Are these simple fan controllers subject to failure?

P.S. I just turned the dial on the controller a few times, reconnected the battery, and the override switch LED is no longer lit. Turned on the ignition and the fan override switch and there's no fan operation. I haven't tested for power at the relays or the fans yet, but fully believe the problem is with the controller and I've ordered a replacement.