I have a Rheem 10 Seer heat pump system in Florida. If the power drops or cuts out for a brief moment, the unit will run, but make a noise (almost like a "grinding" sound). I shut it off and restart it after 10 or 15 minutes and it runs OK. Is this something to be concerned about. What if it happens while I am not home? Will it correct itself? Will it damage the unit?

It's not good, but it's not necessarily the AC's fault Older thermostats especially mechanical ones, don't have what I would call the necessary delay where the freon pressure equilizes.

It's VERY hard for the compressor to start under high head pressure. I've seen this condition so bad that the fuseholders disentegrated.

What should happen is that there should be a 2 to 5 minute delay under the following conditions in AC mode:

1. power fail
2. Unit just turned off

A new thermostat with the feature or an anti-short cycle relay should be installed.