Technician A says that checking ambient temperature as part of an AC performance test is unnecessary. Technician B says that if the AC compressor hasn’t been operating, the high-side pressure should be high and the low-side pressure should be low. Who is correct? A. Technician A B. Neither Technician A nor B C. Technician B D. Both Technicians A and B
The correct answer and explanation is:
Correct Answer: B. Neither Technician A nor B
Explanation:
Let’s analyze both statements in detail:
Technician A says that checking ambient temperature as part of an AC performance test is unnecessary.
This statement is incorrect.
Ambient temperature is crucial when performing an air conditioning (AC) performance test. The reason is that refrigerant pressure and system performance are highly dependent on the surrounding air temperature. For example, on a hot day, both the high-side and low-side pressures will be higher than on a cool day. Manufacturers typically provide pressure and temperature charts, and without knowing the ambient temperature, you cannot accurately determine if the system pressures are within the proper range. Ignoring ambient temperature can lead to misdiagnosis of a perfectly functioning or a faulty AC system.
Technician B says that if the AC compressor hasn’t been operating, the high-side pressure should be high and the low-side pressure should be low.
This statement is also incorrect.
When the AC compressor is not operating, there is no pressure differential between the high and low sides of the system. The pressures equalize due to the lack of compression and circulation. Both sides should read roughly the same pressure, depending on ambient temperature. A high pressure on one side and low on the other only occurs when the compressor is running and functioning.
Conclusion:
- Technician A is wrong for saying ambient temperature doesn’t matter—it’s essential.
- Technician B is wrong for misunderstanding the pressure behavior when the compressor is off.
Therefore, the correct choice is:
B. Neither Technician A nor B