I have a 7 year old Lennox electric heat pump that at first kept tripping the circuit breaker. It had just started tripping the breaker this last month. I used to be able to reset the breaker. Now when I try to reset it, it goes back to the off position. One HVAC personnel came out and said there was nothing wrong with the air conditioner unit. Another company said the compressor was bad. Another company said it seemed like the circuit breaker is bad. I had the circuit breaker replaced, but it is still doing the same thing. Every time I try to reset it, it goes back to the off position. The outside unit will not come on. Does anybody have any suggestions?

CB tripped may cause by loose/ damaged wire or defected (pitted) relay

It sounds like you have a short... could be the compressor or could be a wiring problem. Have someone familiar with electrical circuits troubleshoot it.