My last question is whether it is common for the protector to trip or
whether the fact that it tripped (or tried to) indicates another problem.

Matt

It is very common for it to trip if power is removed from a running
compressor and then re-applied without waiting a few minutes for the
pressure to equalize.

If you reapply power before the pressure equlaizes, the compressor
motor cannot start so the motor will be powered and not turning and it
draws an excessive current that will burn it out in a handfull of
seconds. The protection device is designed to open the circuit in a
second or two.

The protection device will cool and reset itself automatically after a
minute or two.

Almost every refirgerator and air conditioner works this way.

Caution, do not drill into the compressor, it is hermetically sealed.

If you found a replacment protection device, buy it, replace it and
consider that you have done a great job.

Before you buy a new replacement protection device you can bypass the
old protection device just for a short test and verify that the
compressor works etc. but DO NOT use the unit that way. Do not remove
and re-apply power without the protection device in place.


Mark