The utilization of air-source heat pumps has gradually increased since the “double-carbon” aim was established, and the impact of a heating system that consists of radiant floor terminals and air-source heat pumps as a heat source is becoming more evident. However, few studies has been done on the use of such devices as air conditioners in cold climates. The heat pump and floor radiation heating system’s existing laboratory (159 m2), the fan coil’s new dehumidification function, the floor radiation, the fan coil as the cold source’s end, the combined use of the two indoor comfort systems, the cold load bearing ratio, and other experimental elements are all used in this paper. The findings indicate that: 1) when floor radiation is used alone, the average indoor temperature during the day is 28.5 °C, the room’s humidity is 56%, the comfort is poor, and the energy consumption is low; 2) when the fan coil is used separately, the average indoor temperature during the day is 27.2 °C, the comfort is poor, and the refrigerant parameters are demanded; 3) when the two are used together, the fan coil is supported by 55% of the cold load, the floor radiation is supported by 45%, the average indoor temperature during the day is 26.7 °C, with excellent comfort.