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wiring a fan question

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With the cab that I recently bought and put on, I received a 12 volt fan that mounts inside.  I want to hook it up, thinking it will help with fogging on the inside of the soft windshield.  Is there a good place to hook into for power?  The fan has its own switch, all I need is power and ground.  My older tractors had an auxiliary terminal or even a short wire from the ignition switch for extra things, does the 918 have anything like this?

Any advice is, as always, greatly appreciated!!


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I had a fan / heater.  It was small cheap accessory type of unit.  I wired directly to the battery with the supplied wire and had an inline fuse.  It drew a fair amount of power when using the heater portion, so I wanted a direct battery link.  Just had to rememeber to turn it off when done blowing. I didn't always even use the heat, just the fan most of the time.  I set up a plug, so I could leave the wires in place.   It finally died.  I do neeed to get another as it sure worked well with the anti fogging.  As an aside, this direct wire with the plug also let me charge the battery, when need be, (such as forgetting to turn off the fan) without removing the cab to access the hood in my setup.

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That was my first thought as well, although I only have a fan and no heater.  I got to thinking that it would be nice to only have power when the key is on tho.  When weather gets a bit nicer I may try to chase down a wire off the back of the switch that is only hot when it is on, but I don't want to overload some other function with the fan.  I might just end up going the same as you did.  The fan came with a cigarette lighter plug on it, but I don't want the mating plug hanging on the tractor all the time so I cut it off, now just need to wire it.  

Thanks for the imput!


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The only switched power is the red/white wire that goes to  light switch. I don't think that wire is heavy enough] to carry lights and blower.  If you want to run it with ignition switch, you could use a Bosch relay. The coil draws only milliamps and the dry contacts will handle 30 amps. Then you can tap your fused blower power from the starter solenoid terminal stud.

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My solution is to install the +12v distribution board from the older 7100 series tractors.  It allows for easy hookup of accessories (hour meter, snow blower spout rotators, snow cab lights or wiper, etc).

I documented what I do in my Triad to Command post:

First dismount the interlock relay, circuit breaker, ignition switch wiring connector and unwire the solenoid load side posts:


Prepare the distribution board (Simplicity #1665230):


Besides the "stand-off" washers used to keep the connector mounting rivets (on the backside of the board) from contacting the side of the dash tower, I put a full face plastic insulator against the dash tower.

The holes are still in the side of the dash tower to mount the board:


Mount the board, circuit breaker, and interlock module:


The interlock module is mounted using just 1 bolt (as OEM) to an existing hole just under the hydro lever safety switch. (Later in the process when I went to connect the interlock module to the wiring harness, I decided it was better to reverse the module mounting so that the wires were pointing up and toward the dash tower. I had to expand the mounting hole to 1/4" since only the OEM bolt side had been enlarged)

You can then run a heavy wire from the accessory terminal of the ignition switch to the terminal board to avoid the issue BLT posted about.  The OEM 15 amp breaker provides protection for all accessories wired to the board - if you're running a heater, I would think you'd want to run a direct wire from the battery as Brett suggested.  If you want to have it shutdown, then use a relay to kill the "direct to battery" circuit when the ignition key is "off".


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4 hours ago, Brettw said:

Bill, that has to be the cleanest dash tower I have seen, short of new.  75th Anniversary fresh out of the box?

No, the pics above were after I cleaned it up.  Although the dash tower was the cleanest I have come across.  Might have been because PO had already removed the dead Triad and gas tank.  I'm thinking he blew it out at a minimum:



Even the engine area wasn't too bad:



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