Popping fuses like popcorn

[beast]

Ok, so I've connected a vmax battery to a blue sea 100A fuse block. Positive side of battery goes to a battery switch, then a 100A fuse, then to the fuse block. Negative side of battery goes to vehicle chassis. As does the negative side of fuse block. There is only one thing wired to it: a maxair fan deluxe. Max draw: 12.5A. Currently popping 15 and 20 amp fuses when battery switch is turned on. Have tried attaching fuse block to negative side of battery, same result. Put fuse before switch, same result. Wires from battery to fuse box are 4AWG on pos and negative. Ground wire to chassis is 2AWG. not sure why I keep blowing fuses, could use some help please!

 

[abnorm]

You Probably have a SHORT in the Fan to fuse block circuit …….You didn't tell us about these wires..….insulation on the positive is cut or stripped and touching metal ? pinched ? Bad Fan ?

 

[beast]

The wires on the fan are attached to the fuse block with crimped on circle connections. It could be a short in the fan, I suppose, I didnt check that

 

[highdesertranger]

remove the wire from the fuse block that goes to the fan, does it blow the fuse now?

if the answer is no, reconnect the fan wire and disconnect the wire at the fan. does it blow it now?

if yes the problem is in the wire to the fan.

if no then the problem is in the fan.

highdesertranger

 

[beast]

Good advice sir. I'll try that today, and let you know. Thank you much

 

[beast]

Ok... so first off, thank you hdr for the advice. I figured out it was not my setup, and began checking my wires back to the fan. And found my problem. Fun fact about maxair fans: wire color scheme does not follow normal 12v circuit colors. What that means is: the black wire should not be attached to ground, and the white wire is not +12 volts. Indeed it is the wire scheme of an AC circuit where black is death and white is neutral. Upon switching my wires, my fan now works beautifully. ?

 

[MikeRuth]

Glad you found the error, What that also tell's us is that the MaxAir fan has no REVERSE POLARITY protection!

 

[beast]

Well it kinda does... it blows the fuse. Kind of a pain on the a$$ more than anything. Lol

 

[B and C]

It also means you can't put a switch on it to reverse it. I'll stick with my fantastic vent.

 

[maki2]

there is a youtube video that shows putting a reversing switch on the the Maxxair fan but I have not watched it since I don't have a Maxxair.

 

[beast]

Theres a button on the fan itself for intake and exhaust... no need for a polarity switch, guys... lol

 

[highdesertranger]

not all are reversible or should I say do not have a reverse switch built in. especially the older ones. also the design of the fan blade has a lot to do with it. some blade designs can't reverse air flow simply by reversing rotation of the fan. highdesertranger

 

[B and C]

I guess they have some kind of a circuit board in them then that would cause the fuse to blow. Mine is simple with only a thermostat, three speed switch and a reversing switch. Oh, forgot the switch that turns it off if the lid is closed.

 

[tx2sturgis]

Indeed it is the wire scheme of an AC circuit where black is death and white is neutral. Upon switching my wires, my fan now works beautifully. 

Generally speaking, any RV interior 12v device with white and black wires, such as fans, lights, pumps, etc, will follow residential wiring color codes. Black will be hot, or live, (in other words, positive) and white will be neutral, ground, or negative.

The color code for the fan should be spelled out in the manual that came with it.

 

[B and C]

The lights in my van have black and white wires. The black is ground (normal 12V stuff) and the white is hot.

 

[tx2sturgis]

For old-school incandescent fixtures it really didn't matter which way they were wired. And if you upgraded to LEDs, many new replacement LEDs have universal or automatic polarity.

But if you use a circuit tester, or carefully look at the fixtures, I believe you will find out that the metal socket base itself is connected to the white wire, (negative or ground) and the socket center pin (positive or hot) is on the switched black wire.

Newer (as in recent, or new in box) LED fixtures, fans, etc (for interior RV use) will often have a polarity (but not always) and will normally be set up for: 

black=positive and white=negative.

Obviously there will be exceptions out there in the wild.

 

[B and C]

Mine is the exception then. I replaced the incandescent 1141 bulbs with LEDs. Since replacing the bulbs, I have tapped off the light connection to add some 5V USB plugs.

 

[tx2sturgis]

I didn't include this, maybe I should: The black=hot and white=neutral is a 120v residential standard that got carried over to RVs sometime in the distant past. 

Way back in the day, many RVs had BOTH 120v lighting AND 12v lighting. I don't think it's done anymore, but many classic RVs have both types of interior lighting, and of course, the wiring to the outlets, the 12v bulbs, and the 120v bulbs was standardized (if you want to call it that) to a black=hot and white=neutral (or return).

 

[66788]

It also means you can't put a switch on it to reverse it.  I'll stick with my fantastic vent.

My MaxxAir vent has about 10 fan speeds, forward and reverse.  The vent cover supports are dual and won't rip off like single supports.  Here's the biggie in my book:  the screen and fan blades are removeable from inside the vehicle for easy cleaning.

I initially bought a Fantastic Vent for my first build, the one with reversing and the remote, but didn't use it after seeing the benefits of the MaxxAir.  The red headed step child sits unused in my mini storage.  I've bought only MaxxAir from then on.

 

[B and C]

My screen comes off on the inside. It is either held by 6 or 8 ecrews. As mine is from 2000, the fan blade does not come off for cleaning but the newer ones do. I keep hoping it breaks so they will send me the newer model.