Today I showed up for an evaluation on the 15-year-old York heat pump system the unit was previously freezing up before the homeowner turned the thermostat to off and fan on however when I arrived it was 72° upstairs and the outdoors unit was continuously running this is due to a failed contactor welded set replaced the contactor and got everything operational as it should be however there was an arc flash whenever I opened up the indoor unit I was unable to find anything that was loose or burnt and I was not able to recreate the issue I also recommended replacing the defrost control board for the outdoor unit as a preventative measure but all we did today was replace the contactor