Residential Air Conditioning Systems Mechanic (313D) Certification 2025 – 400 Free Practice Questions to Pass the Exam

When the thermal expansion valve (TXV) is adjusted incorrectly, it can lead to an imbalance in the refrigerant flow within the system. A TXV's primary role is to modulate the flow of refrigerant into the evaporator based on the cooling demand and the temperature of the refrigerant entering the valve. If the TXV is set improperly, it can restrict or allow too much refrigerant into the evaporator.

If too little refrigerant enters the evaporator due to incorrect adjustment, it can cause the evaporator to starve, resulting in inadequate cooling and a drop in the refrigerant temperature. This, in turn, can lead to insufficient lubrication for the compressor, which depends on a gas refrigerant for proper operation. At the same time, if an excessive amount of refrigerant enters, the evaporator may flood, causing liquid refrigerant to make its way back to the compressor. This can lead to a condition called liquid slugging, where the compressor attempts to compress a liquid instead of a gas, which can cause overheating and potentially severe damage to the compressor.

Therefore, the risk of overheating and damage to the compressor highlights the importance of proper adjustment of the TXV to ensure optimal operation and protect the integrity of the system.