Good evening all! Got a Komatsu PC300-6 that I am attempting to fix the A/C blower motor on and the fuse labeled "Radio, cigar lighter, A/C panel, Heater, Window Washer, Knob Switch, auto lubrication" blows immediately on insertion. To find the problem, I disconnected the batteries then connected my meter to ground and to the load side of the fuse and set my meter to Ohms. There is a 3.1 ohm load currently in that circuit. I have disconnected everything I can find which is the radio, cigar lighter, and window washer and the load did not change. I have no idea what the A/C panel is since the panel is all mechanical except for the blower speed control which I have also disconnected. Not sure what the "knob switch" is either and my machine doesn't have Auto Lubrication that I know of. So basically, my question is what is the A/C panel, Knob Switch, and Heater listed on that circuit? I have disconnected other random plugs to see if I can eliminate the short, but nothing has changed. Any help is greatly appreciated!
To be accurate, you must swap the meter's probes to measure twice because the circuit has some diode components. There may also be a shorted circuit diode. See 02 attached files for more details.
Where did you find the wiring diagram for the machine? Everywhere I have looked they want money for it and I'm skeptical about doing that. I do know when testing in Diode Mode, the polarity would be reversed at the probe. Unfortunately the meter I have at my house doesn't have Diode Mode. The Ohm mode reading is the same on either polarity.