Electrically challenged - stumped by fuses (1 Viewer)

[Ocho77]

I have a Dometic CDF-111 fridge as my center console. Power runs from the battery, through a Blue Seas fuse box, then disperses through the truck. The fridge has a GMC 8amp fuse in-line. When I put a 10amp fuse in the fuse block, the 10a blew as soon as I powered on the fridge. I put a 20a in the fuse block and the fridge worked. I turned it off, and when I went to power it on again a few minutes later, it blew the 8a in-line fuse.

1. Do I need a 15a fuse in the block?
2. I'm electrically challenged, so why would the 10a fuse blow before the 8a fuse?

Thanks for any insight!

 

[terrx]

I have a Dometic CDF-111 fridge as my center console. Power runs from the battery, through a Blue Seas fuse box, then disperses through the truck. The fridge has a GMC 8amp fuse in-line. When I put a 10amp fuse in the fuse block, the 10a blew as soon as I powered on the fridge. I put a 20a in the fuse block and the fridge worked. I turned it off, and when I went to power it on again a few minutes later, it blew the 8a in-line fuse.

1. Do I need a 15a fuse in the block?
2. I'm electrically challenged, so why would the 10a fuse blow before the 8a fuse?

Thanks for any insight!

There's a CDF-11 which is spec'd at 2.5A. Is a CDF-111 similar? If 8A fuse came with the fridge when new and your fridge is spec'd at 2.5A or similar, then stick with the original 8A fuse and figure out what's wrong. Try connecting the fridge directly to battery via original power cord with 8A fuse, and see if it runs w/o blowing the fuse. If it does then something is wrong with your truck wiring between battery and fridge when it's mounted in truck. Perhaps too much voltage drop?

 

[Ocho77]

There's a CDF-11 which is spec'd at 2.5A. Is a CDF-111 similar? If 8A fuse came with the fridge when new and your fridge is spec'd at 2.5A or similar, then stick with the original 8A fuse and figure out what's wrong. Try connecting the fridge directly to battery via original power cord with 8A fuse, and see if it runs w/o blowing the fuse. If it does then something is wrong with your truck wiring between battery and fridge when it's mounted in truck. Perhaps too much voltage drop?

You are correct, CDF-11. Small fridge. Thanks for the input! I’m wondering if something isn’t grounded correctly. I despise electrical stuff.

 

[brownbear]

Okay so test one.
1) take a multimeter and put it to ohms, you are going to measure the resistance. a lower number means it shorted to ground and will blow the fuse straight away. to read this you take the meter and put the red probe to the power wire and the black wire to the ground wire first and to the chassis or metal of the fridge that could be in contact with ground.
If you see 1 ohms or .0 ohms it's a short. look at the wires and make sure they are not touching prior to the electronics of the fridge.
I would keep the 8 amp fuse in the in line holder. A new one.
DC motors vary in ohms, as you are measuring thru the brushes and coil etc. SO maybe 5 ohms or so might be normal, maybe even higher like 15 ohms.

You should be able to use a 20 amp in the fuse block and if there is an issue the 8 amp will go first. The manual will say what fuses to use.

Not all fuses are equal. Some are called slow blow. Meaning they can handle a surge or some extra draw of current than their rating. SO yes a 10 amp may fail before an 8 amp if it is this kind.

The meter is the tell tail sign if you have a short.

 

[MoJ]

Is your wiring sized correctly? The manufacturer will spec the minimum. For reference, a larger 50 quart ARB requires a min of 10ga and uses a 15 amp fuse.

 

[brownbear]

Here is a lower amperage chart too.