I have a Water Furnace ATV040 B110 CLT. A couple of days ago we got home to a hot house, upon looking at the status lights the low pressure  light was on.

I cycled the circuit breakers and it kicked on, but the fan wouldn't run,  so I took it out and opened up the motor. The magnets had come unglued from the shaft.
When I pulled the magnets out I didn't note their placement or direction. I don't know if it matters or not. I believe I have them in right but I'am not 100% sure. Any how when I got it all back together it  fired up and ran, although I don't feel like the fan is pushing as much air.

I thought that the low pressure light came on and shut the unit down because of no air flow, but at least once every couple of days it goes into the low pressure mode. Cycling the circuit breakers makes it come back to life for a while.

My search led to Steve5212's post about his problem except his is the hi pressure kicking it off.

We are having the same weather conditions so I don't know if I am dealing with the dry issues or if I have a air flow problem or something else.

The coil is relatively clean, the filters are clean and the coil is not icing up.

Any thoughts?