What effect does a zone damper that fails to open have in a heat pump cooling mode?

When a zone damper fails to open in a heat pump cooling mode, it restricts airflow to a specific zone or area of the building. This limited airflow can result in a number of issues within the system's operation. A significant effect of reduced airflow is that it can lead to low suction pressure in the refrigeration circuit of the heat pump.

In cooling mode, the system relies on proper airflow across the evaporator coil to efficiently transfer heat. If the zone damper stays closed, there is insufficient air to absorb the heat from the indoor environment, which reduces the amount of refrigerant vapor reaching the evaporator. Consequently, this can cause the pressure in the suction line (the line carrying refrigerant back to the compressor) to drop, leading to low suction pressure.

Low suction pressure can lead to inadequate cooling performance, and if it persists, it can also contribute to further operational issues within the system. However, it is important to note that while low suction pressure is a consequence of a damper not opening, other choices do not accurately reflect the direct impact of this situation.