DCC Fan Controller--Fan Runs After Key Off Adjustment?

FastDriver · Aug 1, 2025

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.

AeroCoupe · Aug 1, 2025

I have a DCC and Mark VIII fan on the Coupe and when I turn the key on it starts the fan softly runs pretty slow until the car builds some heat. Shut the car off and it spools the fan down over about a minute and like FastDriver I have yet to notice a drain on the battery because of this. I'm pretty sure you have done so but go back over your install and just verify you have it per the instructions. The temperature sensor has to be near the outlet of the radiator for the fan to operate as intended. If the temp sensor is faulty then I want to say it will default to running at 100% but I cannot confirm this.

ZephyrEFI · Aug 1, 2025

Yeah, that is how it operates. It's no more than a minute that it continues to run. I guess I'm just a bit paranoid about my battery because of how it can lose charge just from sitting (I'm talking months). I feel like if it's died once, it's more likely to do it again. In the past, the car has sat a lot more than I intend that it will once I can use the car the way I've always wanted. If that makes any sense, haha. But I've had batteries die from sitting during warm months too, not just winter. I don't know if that's typical or not, but I've checked for excessive current draw and there really isn't any. Mostly, I guess I just don't trust batteries. It's a known fact that they aren't made as well as they were in the past, lasting 3 years rather than 5 or more.

I hear what you're saying though. Maybe it's a control thing. I MUST HAVE CONTROL. haha

FastDriver · Aug 1, 2025

Draining a battery repeatedly absolutely kills it. In both turbo cars, I've got the batteries mounted in the cabin & a cutoff switch behind the license plate. Both of those batteries are 10+ years old, at this point, and still working fine. They're top-dollar NorthStars, though.

Since I'm an idiot all the time, I'll leave the parking lights on at work, or the GPS on after driving home. I smoke the battery in my daily all the time. Fortunately, Walmart has a pretty lenient battery warranty exchange. I pretty much just show up with my 9/16" wrench, 10mm socket & ratchet, receipt, and swap it over in Walmart's parking lot every few years. Honestly, I'm pretty impressed with EverStart cheapos. They punch way above their weight class.

Bottom line, if your car sits long enough to drain 'em, get a cutoff switch, get cheap Walmart versions, or put 'em on a battery tender that will monitor and trickle-charge as needed (CTEK 8-stage deals are my personal preference).

JD1964 · Aug 3, 2025

I have a DCC controller too. Mine also spools down over a short period of time after shutoff.

ZephyrEFI · Aug 3, 2025

FastDriver said:
Draining a battery repeatedly absolutely kills it. In both turbo cars, I've got the batteries mounted in the cabin & a cutoff switch behind the license plate. Both of those batteries are 10+ years old, at this point, and still working fine. They're top-dollar NorthStars, though.

Since I'm an idiot all the time, I'll leave the parking lights on at work, or the GPS on after driving home. I smoke the battery in my daily all the time. Fortunately, Walmart has a pretty lenient battery warranty exchange. I pretty much just show up with my 9/16" wrench, 10mm socket & ratchet, receipt, and swap it over in Walmart's parking lot every few years. Honestly, I'm pretty impressed with EverStart cheapos. They punch way above their weight class.

Bottom line, if your car sits long enough to drain 'em, get a cutoff switch, get cheap Walmart versions, or put 'em on a battery tender that will monitor and trickle-charge as needed (CTEK 8-stage deals are my personal preference).

So, you must've never tried the green wire thing, huh? I've reversed the diode, but I'm still not sure I want to try turning it to run to see what happens... I feel like I'm sort of committed to though, since I ran this wire intending to be permanent, so I did a really nice job, haha.

And I wonder what the yellow wire is for. I hate that the information isn't just available. Nope, it's a secret. The FAQ section you guys were talking about before doesn't seem to exist anymore either. I mean yeah, it probably won't hurt my battery to just leave it alone, but ggggrrrrrrrrr....

FastDriver · Aug 3, 2025

Nah, man. I've been daily driving for more than a year. It seems fine to me. I'm kicking that battery's ass, but I don't think it's the fan. I just accidentally drain it a few times a year.

ZephyrEFI · Aug 7, 2025

Well, I waited a week for an answer and haven't gotten one yet, so we're going to live dangerously. I turned the diode around and turned the key to run. Nothing happened. So far, so good. Started the car and turned on the A/C. Fan comes on at 50% as expected. Go for a drive. When I got back, with the engine running, the fan kicked on. I turned off the key, and bingo! Fan turns off! I am happy!

JD1964 · Aug 10, 2025

ZephyrEFI said:
Well, I waited a week for an answer and haven't gotten one yet

I’ve emailed him twice and got an answer both time but I seem to remember it taking longer than a week. If he does eventually answer, post back and tell us what he said.

ZephyrEFI · Aug 10, 2025

JD1964 said:
I’ve emailed him twice and got an answer both time but I seem to remember it taking longer than a week. If he does eventually answer, post back and tell us what he said.

Will do.

DCC Fan Controller--Fan Runs After Key Off Adjustment?

FastDriver

I was uncomfortably high & wearing a helmet

AeroCoupe

lube between the nut and the face. I know my lubes

ZephyrEFI

Active Member

FastDriver

I was uncomfortably high & wearing a helmet

JD1964

there is enough sticking out to grab on to

ZephyrEFI

Active Member

FastDriver

I was uncomfortably high & wearing a helmet

ZephyrEFI

Active Member

JD1964

there is enough sticking out to grab on to

ZephyrEFI

Active Member

Similar threads

DCC Fan Controller--Fan Runs After Key Off Adjustment?

I was uncomfortably high & wearing a helmet

lube between the nut and the face. I know my lubes

Active Member

I was uncomfortably high & wearing a helmet

there is enough sticking out to grab on to

Active Member

I was uncomfortably high & wearing a helmet

Active Member

there is enough sticking out to grab on to

Active Member

Similar threads

Privacy & Transparency

Privacy & Transparency