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Old 09-10-2019, 01:10 PM   #1
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Magnum MS2012 overtemp / fans not running

Hi, I have a 2014 Tiffin Phaeton with the MS2012 inverter/charger combo. About a month ago, we got an overtemp fault while bulk charging. I did some other searches on here and learned that happens when the transformer or FETs get in the 242 degree temp range. I checked on the MS2012 and noticed that I no longer here the hum of the fans running that I'm pretty sure I've heard before when doing things in that compartment? So I pulled the power, removed the outer cover to inspect the two fans, I even swapped their connections to the PCB board, made sure the blades move freely, etc and no luck.

It seems unlikely both fans would have died? I'd expect if it was a fan problem one would have died but the other would still work right? So i'm hesitant to purchase new ones and replace them, but I will at first opportunity since it's a first troubleshooting step. I'm full time so finding a place or ordering online on the road can be a challenge.

So I cannot help but wonder if there is some other issue. The unit performs fine otherwise.. inverts fine, charges fine although I have to watch the temps and reduce the charge rate when it gets close to 200 degrees to be safe. I haven't had an overtemp alarm since but I can see the box is getting into the 180-190 range for the FET and transformer during bulk charging then it tapers off during absorb charging. I'm also in cold weather now which helps.

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Old 09-10-2019, 02:10 PM   #2
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When overtemp happened, you just need to do a master reset - hold down the small button for 15 seconds and release. That should bring it back working. If need be, call magnum cs they are very helpful.

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Old 09-10-2019, 02:23 PM   #3
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I had the same issue with my Magnum 2810.

I tried everything including resetting the inverter, without any luck. I finally found that both fans werenít working. Replaced them and no more overtemp warning.

The fans are cheap and easy to install. Just make sure you are not hooked up to shore power and power off the inverter, before opening it up to install the new fans.
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Old 09-10-2019, 09:19 PM   #4
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Yes, i've done a reset per the manual.. no luck. I can let a bulk charge cycle happen and can see the temp rise into the high 100s and the fans do not start. I will replace them, but it just seems odd that BOTH would decide to die at the same time.
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Old 09-11-2019, 09:00 AM   #5
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Originally Posted by cmillet77 View Post
Yes, i've done a reset per the manual.. no luck. I can let a bulk charge cycle happen and can see the temp rise into the high 100s and the fans do not start. I will replace them, but it just seems odd that BOTH would decide to die at the same time.
The fans are not the best quality and are not sealed so all the dust and dirt get into the motor. Donít try and get other cheaper priced sealed fans as they may not function with Magnums system. They need to be PWM fans to work. New fans when spun with a finger will rotate at least 10 revolutions before stopping.

You can take the fans out and hook them up to a 9v battery or a 12v source and see if they work. Seeing as you have a 2014 they are most likely not working.

You need a rather long skinny torx bit screw driver (donít remember the size 15 or 20 I think) to release the metal band holding the fans down. Also you will most likely have to remove a large cable going to the transformer to get them out. Take a picture ahead of time so that you get the orientation right. Air sucks in the small end and blows out the large end.

I am about to change the fans in my 2012 inverter as they are getting noisy, did the fans in my 2812 last winter when they failed.

Good luck changing them out.
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Old 09-11-2019, 12:19 PM   #6
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Thanks.. I've got the cover off and can see how the fans are easily replaced. I ordered two from Marine Parts Source for $40 shipped.

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