What is the result of having a dirty evaporator and low evaporator pressures?

When the evaporator is dirty and there are low evaporator pressures, the result often includes low compression ratios. A dirty evaporator impedes airflow and reduces the efficiency of heat exchange, leading to lower refrigerant vaporization rates. Consequently, the pressure in the evaporator decreases, which goes hand in hand with the pressures seen in the suction line leading to the compressor.

The compression ratio is defined as the ratio of the pressure of the refrigerant in the discharge line to the pressure in the suction line. If the evaporator pressure is low due to a dirty coil, the suction pressure drops as well. As a result, the difference between the high-side and low-side pressures decreases, leading to a lower compression ratio.

Low compression ratios can cause a variety of operational issues for the refrigeration system, including inefficiencies and possible compressor problems, as the compressor has to work harder to maintain cooling efficiency. Additionally, the lower evaporator pressures mean that the system is not effectively absorbing heat, further contributing to operational challenges.