What can happen in an A/C system containing moisture at the hottest part of the day?

In an air conditioning system, the presence of moisture can lead to significant problems, especially when operating under high temperatures. When moisture is introduced into the refrigerant circuit, typically from the air or leaks in the system, it can migrate to areas of the system where temperatures drop. The thermal expansion valve (TXV) is a critical component that regulates refrigerant flow and can be susceptible to freezing under certain conditions.

At the hottest part of the day, when the system is working hardest to cool, moisture that has entered the system can condense and freeze in the TXV because the temperatures are sufficiently low in this component to create frost. This ice buildup obstructs the flow of refrigerant, leading to a drop in system performance.

The accumulation of ice at the TXV can inhibit the refrigerant from circulating properly, which can lead to inefficient cooling and potential system damage as increased pressure builds up within the system. If the TXV is completely blocked, it can lead to significant issues, such as the compressor potentially overheating or even seizing due to constant high pressure and inadequate refrigerant flow.

This context helps underscore why moisture presence can lead to freezing issues at the TXV, impacting the overall function and efficiency of the system.