In chilly winter weather, a heat pump blowing cold air is probably not what you want nor expect. Heat pumps provide year-round comfort control by consolidating both air conditioning and heating modes into one unit. In winter, the temperature of circulating air must be appropriate to keep the house comfortably warm and energy efficient. If that’s not happening, here are some of the reasons why the unit might be blowing cold air in winter heating mode.

• The thermostat setting is wrong. In cold weather, the thermostat controlling the heat pump should be in heating mode and should also be set to “Auto” instead of “On.” If the unit is in “On” mode, the system fan will keep circulating air even during brief intervals when the heating function has temporarily cycled off. Cooler air may be temporarily noticeable circulating into rooms. This may cause the mistaken assumption that there is a defect in the heating system. Keeping the thermostat set in “Auto” mode avoids this.
• Mechanical issues. Certain mishaps with heat pump components can cause the system to blow cold air while in heating mode. Chief among these are a loss of refrigerant due to leakage somewhere in the system. Alternatively, the reversing valve that controls refrigerant flow may have become damaged or completely failed, causing the direction of flow to be incorrect for heating mode.
• Defrosting function. Frost may form on the heat pump’s outdoor coil when the unit is in winter heating mode, impairing the efficiency of heat extraction from cold winter air. To defrost coil ice, the unit automatically reverses refrigerant flow at brief intervals to heat the outdoor coil. For that short period, the heat pump actually operates in air-conditioning mode. Cooler air may therefore be briefly noticed coming from HVAC vents. If this normal function seems to be activating too frequently — or the defrosting period continues for too long — have a qualified HVAC technician check the unit.

If your heat pump is blowing cold air in the winter when what you want is comfortable warmth, contact the heating professionals at Jackson & Sons.