John Deere 7220 Ac fan motor failure

[gwwhitaker1]

I have a 2007 7220 tractor and the ac fan blower motors both stopped at the same time in the middle of a hay field. All the fuses and relays checked ok. I disconnected the plug at the motor and I have 12 volt at both terminals that come from the fan switch thru the resistor when the switch is in the off position. When the switch is moved to any of the three run positions both terminals going to the motors have no voltage. When I put a 12volt test light on the terminal I can hear a relay making contact. I suppose it is grounding thru the test light. Where can I find a wiring schematic for this circuit.

 

[Tx Jim]

JD 7220 technical manual

 

[Zebrafive]

I don't have the tech manual, so this is ONLY how I THINK your system works.
There should be TWO relays: a fan relay, and AC relay (for compressor clutch)
There should be THREE fuses: One for EACH fan (TWO), and one for the AC clutch
The AC relay and fuse will not affect the fans, so we will not worry about them.
When the KEY is ON the Fan relay will be powered. This will then power the two fan fuses. (and the AC relay, but does not affect fans) So check you have 12 volts at the two fan fuses (not that they are good, but they are powered) if not powered suspect the fan relay.
If the fan fuses are powered, you should have power to both fan motors.
The fan switch connects the fans to ground. There are resisters to give three lower speeds. Resisters are not used for high speed. So even if the resisters are bad, high speed should still work.

I suspect any of the following:
broken wire(s) or bad, loose connector(s) between fuses and fan motors, or fan motors and fan switch.
bad ground connect to fan switch
bad fan switch
bad fan relay


I doubt both fan motors failed at the same time.

 

[gwwhitaker1]

I know where the relays for the motors and the ac clutch are located and will give both a check with 12v across 85-86 to check continuity across 30 and 87. I will also jump across 30-87 as I have constant voltage at 30. I also have voltage at 85 on both relays with key on. If ok there I will check voltage on both sides of fuse with fuse installed. I will also check both motors by wiring them direct to 12v and ground as I have heard that the motors JD uses develop flat spot on the commutator that are dead. If everything ok all that is left is the fan switch switch or broken wires. I didn't realize the fan switch was providing a ground for the motors. I will let you know the outcome. Thanx.