What does a dirty evaporator in an air conditioning system commonly cause?

A dirty evaporator in an air conditioning system significantly impacts its performance. When the evaporator coil is dirty, it restricts the airflow over the coil, leading to inadequate heat exchange. As a result, the refrigerant does not absorb enough heat from the indoor air, which causes the temperature within the system to drop.

This poor heat absorption can lead to both low suction pressure and low discharge pressure. The low suction pressure occurs because the refrigerant is not able to evaporate properly due to the lack of heat exchange, which means less refrigerant enters the compressor. Consequently, this reduces the overall pressure in the system. Similarly, low discharge pressure arises from insufficient refrigerant vapor being compressed by the compressor, which translates into lower pressures in the discharge line.

In short, a dirty evaporator adversely affects the essential functions of the air conditioning system, leading to the combined issue of low suction and low discharge pressure.