Fridge Circuit Blowing Fuse

[Klompen]

My 2017 SMB is equipped with 2000 watt Magnum Inverter & Progressive Dynamics fuse box (with breakers for a/c side). We have Isotherm 65 refrigerator that has performed flawlessly, but I have a strange problem where the fuse for the fridge circuit blows even if the fridge is turned off.

I first discovered this after the fridge was turned off and the door was in the vent position with the light off. I went to turn on the fridge, but found nothing working and discovered that the 15A fuse was blown. I replaced the fuse and it sat in the same state for several days, but worked when I turned it on yesterday. It ran okay all day yesterday until this afternoon when it apparently blew while the fridge was running.

The only commonality that I know is that internal temps in the van have been 115+ as it is stored in Phoenix. I would never camp like this, but I needed to keep some stuff cold for a couple of days. It makes no sense to me that the fuse should blow with no load on the circuit, and I did not witness it. Is this possible? Any ideas on what could cause this?

[Scalf77]

So if the wire going to fridge shorts out to something, like ground, it would be very possible to blow a fuse when the fridge is not running. I would check the connections to the fridge, and trace the wire from the fridge back to the fuse box if possible. It also never hurts to check the ground side either.

-greg

[ctb]

Did you check for mice/rodent damage? Being stored just wondering...

[posplayr]

I had a recent episode with my Gialand inventor. It would trigger and error when I let it run a low frige load overnight. Turns out the high speed switching network in the inverter was shorting the dc input from the battery. It pulled the battery down to 6v intermittently but was not long enough to blow the fuse.
kind of scary and makes me wonder if the internal fuse is actually in line with the battery.

This was intermittent at first but after 3 days it went hart fail but no blown fuse. You need a digital storage scope on the dc input to see what I’d going on. The voltmeters just averaged it all out and showed 13v.

[Klompen]

I have been watching this carefully over the last few days. I can confirm that the fuse will blow if the 12 volt system is on, the fridge turned off, and the door light off. There should be no draw on that circuit at this point, but it seems as if a draw starts if the temp in the van is too high. This draw is higher than 15A and thus blows the fuse. Yesterday the temp in the van reached 105f with no issues so I don't know what the magic temp is and I don't know what the temp is in the refrigerator compartment. More testing today and I will put a temp sender in the fridge compartment to see the difference between it's temp and the general van temp .

[Scalf77]

Another thing to consider is that just because the unit is off, doesn't mean that the power is going to the. In this case the power is still available to the controller. While the switch is off, their still is at minimal, some etching in the controller that has power before it actually circuit for the on/off switch.

I would try disconnecting the power connection from the unit, and see if the failure goes away. Obviously you may need to meet your temperature condition to precipitate the failure. Obviously, removing the fridge will most likely be needed for access to controller. Take your time, remove the fuse while performing the task and tape off the power connections. While your unit is removed check the cable run to make sure nothing looks out of the ordinary as much as you can.

If you can take a picture of the controllers part number while your in their, as this may be a good reference part number for the future.

Good luck and happy hunting

-greg