A/C humming

tropical36 wrote:
Had some issues with our dometic. Story short, after replacing the burnt out fan motor, it still wouldn't run, although the compressor always would. Disconnected the connector from the inside and checked it for burnt contacts or whatever and pulled the 3amp pcb fuse which was OK. reinstalled both and the fan took off????
Have no clue as to why except that it might have reset the control board.
About a year or two ago the old fan motor froze up. Disassembly and some grease on the bearing surfaces cured that problem until now. Did this most recent repair in this campground as I had the new motor on board and so far so good.
As a side note, the fan motor doesn't use a start capacitor and shares the run capacitor with the compressor, so one might want to consider these items in troubleshooting also.

Update:
Last trip out the fan wouldn't start again. Checked it out and it would on med and slow speed, but not on high or auto. So, after deciding we didn't really like the fan running non-stop, I went in for exploratory surgery with the thought of either replacing the high speed relay (there's three), using an external wired to the board or providing a by-pass circuit and choosing either med or low for the fan speed to operate automatically. Turns out the printed circuit itself was severed and appeared to have been burnt open. Did an easy fix by soldering a small piece of #14awg solid copper wire across the gap and it's now as good as new. Just can't believe the relay contact survived and must say the board itself is very well built. This whole assembly might be very useful in case of a new A/C replacement, as I'm not so sure one can buy a new unit that will tie in to the existing system without this add-on for control and the EMS shedding system. It does use telephone cords between the units and the thermostat.