For this call I performed an evaluation. The breaker was tripped due to incorrect breaker size for one set of heat strips. I suspect that the two heat strips with power were unable to maintain heat during cold temperature while the heat pump went through its defrost control cycle. I disabled one of the 4 heat strip and reset the breaker. There was a 30 degree split on emergency heat and I set the defrost cycle to 90 when originally set to 30. Thank you for choosing comfort experts, have a great day!