What can a restricted drier cause in a heat pump system?

A restricted drier can cause lower than normal suction pressure in a heat pump system because the restriction impedes the flow of refrigerant. The drier is designed to remove moisture and contaminants from the refrigerant, but when it becomes clogged or restricted, it can create a bottleneck. This bottleneck leads to inadequate refrigerant flow into the evaporator coil, ultimately resulting in reduced pressure on the suction side of the system.

As the evaporator coil requires a certain volume of refrigerant to absorb heat and maintain proper operation, any limitation in the flow can prevent it from reaching the necessary levels of heat exchange, thereby leading to lower suction pressure.