Low suction pressure (low-side pressure) is a common symptom in heat pump and refrigeration systems. It indicates that either refrigerant mass flow is restricted, or heat transfer at the evaporator is insufficient.
Potential Causes
1. Low Heat Load (Airflow)
Dirty filters, restricted ducts, or a failing indoor fan motor will decrease heat transfer to the liquid refrigerant, reducing pressures.
2. Refrigerant Undercharge
A leak in the coils or joints reduces the volume of refrigerant, dropping vapor pressure at the compressor suction port.