Got a weird one. Kenworth T800 Just about all components replaced including motor. Good ground at the motor. 25 amp breaker replace with a 30 amp. It runs for an hour or two then pops the breaker. Motor stops then starts for a few seconds and then the breaker pops. Wondering if someone has run into this before Thanks! Rob
Haven't run into that exact scenario... but sounds like a wire in harness is shorting out after warming up.... maybe... what does the T800 use for speed control?
Resistor located in the heater box on right side by the right kick panel next to door.
It has a 3 speed switch and the resister was replaced
If it was mine to fix I would be putting an amp clamp on the blower wire at the breaker and watching it from time to time to see what it does. I have a big ole Fluke 381 or whatever for starter motors and such, but I have found this little one http://www.extech.com/display/?id=14179 is good for reading things like pesky battery drainers in the 4A mode and in the 80A mode it would be perfect for this job. If you can't see exactly what is happening then you are shooting in the dark.
After this last winter I don't trust Paccar much on blower motors. Got one that was the wrong rotation, Got another that was a multispeed motor for a truck that had a resistor. took a while to get both worked out.
I have this Innova, advertised https://www.amazon.com/Innova-3347-Digital-Multimeter-Probe/dp/B0015S9SWW to work with any digital meter.
Was the 25 amp the original and what belongs there, if so I would put that back and not go to 30 amp. Just find the shortening out or it's overloading trying to run cause it's seizing up and grabbing more amps to do so. Or as others are saying the resistor...
Original breaker was 25 Motor was replaced last year. Pretty sure it's the same problem but will check. ( I didn't do the work) Not much time to tear things apart Just hoping someone may have had a similar issue. It's not a dead short, those are "easier"