ESCO Air Conditioning Practice Exam

When the evaporator in an air conditioning system is dirty, it restricts the flow of air and heat transfer, leading to reduced cooling efficiency. This restriction can cause the refrigerant to stay longer in the evaporator coil, resulting in lower evaporation rates and higher evaporator temperatures. As a result, the compressor needs to work harder, leading to high suction pressure and high discharge pressure. This indicates that the correct answer is high suction pressure and high discharge pressure.

The other options are incorrect because they do not reflect the typical symptoms associated with a dirty evaporator coil. A dirty evaporator coil is more likely to lead to an increase in both suction and discharge pressures due to the reduced efficiency of the cooling process.