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Discussion Starter · #1 ·
My 1990 JD 9500 has the variable fan speed not working. I removed the motor from the gear, the gear moves freely. I tested the motor by hooking it to a 12v battery, and it spins forward and reverse by hooking it normal and also reversed polarity so I know it's ok. I removed the fan switch from the right arm console, the switch ohm checks good for fast and slow speeds so it's ok. I checked the circuit breaker in the main fuse/relay panel, the circuit breaker has power through it. I cannot identify which relays are for the variable speed fan, the circuit panel only shows circuit numbers under the relays, and the owners manual does not show what each relay is for. Any help will be appreciated, I will probably be going to the JD dealer for a wiring schematic.
 

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I had the same problem on a 9760 and my fix was putting a brand new circuit breaker in it was located right under the sample door. I did all the same things you did and everything was good. Had JD come out and they said I needs a new circuit breaker. put a used one in for $800 and that fixed it.
 

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southsask9400 comment on there being two relays hits home as we had an issue with one of our 9600's a few years ago as the fan speed would increase but not decrease. It turned out to be the relay for speeding it up. I am not even sure if the relay even had failed, it may have been a poor connection but regardless it was the relay circuit that gave the problem. As everything else checks out I'd mark those two relays as Southsask mentioned so you know which spots they came from and pull one and install a known good one and see if you get some action and go from there.
 

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Discussion Starter · #8 ·
The K9 and K10 were the correct relays in the main panel for the variable fan speed, I removed those two relays and temporarily jumpered the 30 terminal to the 87 terminal for troubleshooting one at a time ( sending power down to the variable fan speed motor) I found one faulty relay right next to the motor, and also a poor connection in the connector next to the motor. Variable fan now works, Thanks everyone for the replies!
 

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Does it rotate the fan motor screw one way and not the other ( speed up only or slow down only ? )

If that is what its doing, as what was previously stated you can take a known good relay and swap it into locations K9 and K10 to experiment with. What I discovered and I guess this isn't just our combine then, K9 speeds up the fan and K10 slows it down which is the exact opposite of what the book says so I have a feeling its an error in the book. By the way the page in the owners manual is 95-2 where it lists the relay location codes and what functions each controls.

Also if your fan won't go up or down in speed, make sure the screw is not butted up against one of the stops and jammed as that sure can happen, or that the nut has seized onto the screw.
 

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I know this is an old post but I'm having the same problem exactly how do you chk the ohm? to see if the switch is good. Or can i just swap it with another switch and c what happens
to test Ohms, use the upside down horseshoe on a DVM.

When switch is open, its usually shown as a OL on a meter. It will be the same reading you get as not touching the meter probes to anything.

When switch is closed, it should read 0.0-1.0 on a meter. It will be the same reading you get when touching the meter probes together.

The fun part is figuring out which terminals on the switch are the correct ones to test...for that you need the schematics.

A rule of thumb on a typical SPDT rocker switch is that the middle terminal is common, and if you rock the switch one way, the opposite terminal should connected to the common. Example, push the switch up, the common and bottom terminal should connect.
 

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I should have mentioned in my last post that I didn't even comment on the dash switch because its more likely to be some other electrical or mechanical issue vs that switch, not to say it can't fail. Some years ago when I first had the issue crop up, I had a mechanic very familiar with this series drop by and the first thing he did was pull the circuit board which goes to show those relays can be a sore spot or even the connection they have on the socket of the printed board due to any moisture that may find its way into that housing in the grain tank.
 
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