ESCO Air Conditioning Practice Exam

A rise in evaporator pressure causes the automatic expansion valve to begin to

1. Close

2. Open

3. Operate normally

4. Shut down

The correct answer is: Close

When an automatic expansion valve is installed in an evaporator, it is designed to maintain a specific pressure within the evaporator. This pressure helps to determine the temperature within the evaporator, which in turn affects the overall efficiency of the system. A rise in evaporator pressure would indicate that too much liquid refrigerant is flowing into the evaporator, which could cause the system to become overloaded and potentially damage the compressor. The correct response, therefore, would be for the automatic expansion valve to begin to close, limiting the amount of liquid refrigerant allowed into the evaporator and helping to maintain the proper pressure and temperature within the system. The other options (B, C, and D) are incorrect because they do not address the potential issue of too much liquid refrigerant entering the system, which is ultimately the main concern in this scenario.