20 Amp Fuse Keeps Blowing for front of house

[ChefChris]

I replaced the exhaust fan in our kitchen with a Dometic fantastic fan, the one recommended online as the replacement and the same brand we had before. Everything seemed to be working just fine when I tested it. However, on our last trip out, we kept blowing the 20 Amp fuse that works the front of house lights, the exhaust fan, etc. Went through 2 of the 20 amp fuses. And it sparked when I changed it.

Curious if this replacement fan might be creating the overload and blowing the fuse and if I should install a larger amp fuse like a 30? I have no literature on the fan except that it was the recommended replacement for the older fan, same brand but 12 years apart.

Thank you!

[Bill]

We need more info.

What year and model is your Trail Manor?
What is the mfr and model number of the original fan?
What is the mfr and model number of the replacement fan?
Where did you see the replacement info? Was it on the Dometic site?
By any chance, did you reverse the connections to the replacement fan?

Do not increase the fuse size.

Bill

[ChefChris]

Hiya Bill-

We have a 2014 2922KS
Manufacturer and model of the fan was a Fan-tastic Vent Corp Fan (beige plastic blades) factory install I'm assuming from 2013 as that was the date on the old unit. P/N: 4019-09 12VDC 2A
The replacement was: Dometic K8017-00 Fan Blade and Motor Assembly - Standard Vent
I google searched for replacement for the unit and that was what I found to be the best option with what was available online.
Did NOT reverse connections when the fan was installed. It worked for a few weeks prior to our trip.
We did have other electrical issues on the trip, the AC power outlets went out until I reset the GFCI. Blew 2 of those 20A fuses that work the front of house.
We were under generator power most of the trip.

[Bill]

Well, all of those things sound right, so I see nothing suspicious there. I do see some indication that the fuse in the old fan was 2 amps and the new one is 4 amps, but that is not enough of a difference to cause the 20 amp circuit fuse to blow. And apparently the fuse in the fan did not blow - only the 20 amps main circuit fuse went out. That fact, plus the delayed appearance of the fault, suggests there is a pinched wire or intermittent ground contact somewhere in the fan assembly or its supply wiring.

My best suggestion is that you dismount the fan again, and make sure all the wires are in place and not nicked. As it goes back together, make sure that all of the electrical parts, especially the tab on the fuse holder, plus the wires going into any wire nuts or connectors, do not come into contact with any metal parts of the fan frame or the opening in the sheet metal of the ceiling. The fact that it is not exactly the same assembly, and is perhaps slightly bigger (based on the larger fuse rating), suggests that there might be enough of a physical size or fit difference to cause an intermittent short of some part to ground. I hate intermittents.

Just for the fun of it, you might remove the fuse from the fan's fuse holder, and continue your trip. If the 20-amp fuse pops again, it pretty well indicates that the fault is not in the fan, or its small extra current load, but in the installation.

Good luck.

Bill

[Wavery]

Just keep in mind that the grounded wire could be anywhere in that 20A circuit.

You are absolutely right to go to the fan installation 1st. Just don't get so hung up on that that you might miss something else. There's a lot of stuff on that circuit....... overhead lights....kill switch on bathroom folding wall..... I think, the toilet..... radio antenna and possibly other culprits, including the wires going up the lift arm to the roof. A quick look around could reveal a different issue.

[rickst29]

Originally Posted by ChefChris

Hiya Bill-

We have a 2014 2922KS
Manufacturer and model of the fan was a Fan-tastic Vent Corp Fan (beige plastic blades) factory install I'm assuming from 2013 as that was the date on the old unit. P/N: 4019-09 12VDC 2A
The replacement was: Dometic K8017-00 Fan Blade and Motor Assembly - Standard Vent
I google searched for replacement for the unit and that was what I found to be the best option with what was available online.
Did NOT reverse connections when the fan was installed. It worked for a few weeks prior to our trip.
We did have other electrical issues on the trip, the AC power outlets went out until I reset the GFCI. Blew 2 of those 20A fuses that work the front of house.
We were under generator power most of the trip.

The OEM 'fan-tastic' vent over the stove is a 12 volts DC fan. You're talking about multiple failures of a 20A automotive-style ATC fuse in the upper right fuse board, right?

The WFCO's circuit breakers for 120 volt AC, and the GFCI WITHIN THE TM are purely 120-volt AC power, they should not have any interaction with a 12-volt DC failure.

A DC fuse should fail whenever 12+V leaks hgh current to the skin. But high DC current from the "+" side of the batteries or converter , either running appliances correctly or "leaking out" badly, goes to the TM frame and reaches the battery '-" from there.

If there was any interaction with re-setting a GFCI (especially an external cmapground or garage GFCI), then an issue has probably also occurred with the power converter.
- - -

If the problem is purely DC, then it before at your your fan replacement. Isolate the problem this wasy:

Steo 1: remove all connections fro the new overhead fan
Step 2: Turn off all ceiling and exterior front shell lighting, using their switches.
Step 2: Put in yet another 20A DC fuse. Did it blow right away?

If so, your problem is in the 12V wiring to reach the front shell ceiling (before any ceiling appliance). Issues with flexed cable going up and in the shell, when raising and lowering lift arms, are not uncommon. Try disconnecting at various points, to determine whether the problem occurs going up the lift arm, or only within the ceiling, or before you even get to the lift arm.

Step 3: If the fuse did not blow, try turning on a ceiling lamp. That should work OK.

Step 4: Only now, and very carefully, test the leasd wire voltage into your new fan unit (before connecting those leads), With the fan totally turned off, connect "-" (grounding). Only then connect 12V+", with the fan turned off.

Did the fuse blow, merely by connecting supply wire? Fan is defective.

Step 5: Turn on the fan. If it pulls nearly 20A and blows the fuse, the fan is again defective.

[rickst29]

(Aside: In any case, I fell the variable and reversible maxxfan products, with rain-resistant covers, to be a better choice).