Preformed heating maintenance on heat pump system. Confirmed thermostat heat anticipator was set correctly Mercury thermostat is working at this time within a couple of degrees of actual room temperature. Confirmed electric heat is working within manufacturer specs 34.8/31.7 Double pole contactor has failed causing loud buzzing noise while energized. Quoted customer and made repair while onsite today. Confirmed all high and low voltage is good and tight. Took amp draw on blower motor and found within specs 2.8 Blower wheel is clean and balanced. Evaporator coil had small amounts of debris on edges was able to brush clean. (Pic of existing filter in photo)Filters provided for customer DONT fit this type of application and should be a washable cut to fit style due to mounting to back of louvered door for electric furnace. Checked refrigerant levels and found within manufacturer specs 55/250. Took amp draw on compressor and found within specs 11.6 Amp draw on condenser fan was within sp