This illustration show you guide on how to test and adjust blower motor for Kubota U48-4 and U55-4 excavator.
1 Remove the blower motor’s 1P connector.
2 Switch the starter switch to [RUN] and the blower switch to  (HI).
3 Measure the voltage between terminal 1of the connector on the switch side and ground on the body.
4 If the voltage is different from the battery voltage (DC 11 to 14V),then there is a fault in the wire harness, blower motor relay, the fuse and/or the starter switch.
Blower motor test
1 Turn the blower motor by hand and check whether it turns smoothly.
2 Remove the 2P connector from the blower motor.
3 Connect a jumper lead from the positive (+) terminal of the battery to terminal b of the connector.
4Connect a jumper lead from the negative (-) terminal of the battery to terminal e of the connector for just a moment.
5 If the blower motor fails to turn, check the motor.
More repair case for Kubota,please refer to:Kubota Trouble Repair