The inside unit on our lennox heat pump is working including the fan but the outside unit is not running at all. Every time that you kick the breaker on, it throws again. At the moment the breaker is off but the outside is humming. I have kicked the breaker on and the fan in the stop of the unit will go around a few times and then stops when the breaker throws. As far as we could tell when we were using the heat setting of the heat pump it was working fine, but stopped after we switched it to the a/c setting. I was wondering if the outside unit has a reset button that may need to be pushed for the compressor in the outside to start working?? Oh yeah, I have changed the air filter, so I know it's not that.

Sounds like a dead short somewhere,, could be contactor,, could be locked compressor,, could be a burned wire end on the compressor,,