I've had the DCC in for more than a year at this point. I have to say, I have never felt a pressing need to go back and install any switch. Fan works great, and the minute max that it runs after shutting off the car sometimes has never drained the battery or been otherwise noticeable. I do love how it starts softly & doesn't spike electrical load like the fans in my other cars do. I'll probably install one in each eventually.
Regarding your comment Zephyr, I am not an electrical guy, but I believe the diodes purpose is to allow signal to run only 1 way, from ignition to the fan. The diode prevents signal from the controller from feeding back into the ignition circuit. So, if it goes full blast when ignition is on and cuts off when ignition is off, then I'd say you have it right. However, going full blast is obviously not the desired operation.
Regarding your comment Zephyr, I am not an electrical guy, but I believe the diodes purpose is to allow signal to run only 1 way, from ignition to the fan. The diode prevents signal from the controller from feeding back into the ignition circuit. So, if it goes full blast when ignition is on and cuts off when ignition is off, then I'd say you have it right. However, going full blast is obviously not the desired operation.


