The air-conditioning compressor will not engage. When a scan tool is connected it indicates that there is no A/C request signal. Technician A says that the refrigerant system may have a faulty thermostatic expansion valve. Technician B says that an engine cooling system thermostat that is opening too soon could be the cause. Who is correct?
A Technician A only
B Technician B only
C Both A and B
D Neither A nor B
The correct answer and explanation is:
The correct answer is D. Neither A nor B.
Explanation:
In this scenario, the air-conditioning compressor is not engaging, and the scan tool indicates that there is no A/C request signal. The absence of an A/C request signal suggests that the issue lies with the electrical or control system that operates the compressor, not with the refrigerant or engine cooling system directly.
- Technician A’s suggestion: The thermostatic expansion valve (TXV) is responsible for regulating the flow of refrigerant into the evaporator. If the TXV were faulty, it could cause improper refrigerant flow, which might lead to issues like freezing of the evaporator or poor cooling performance. However, a faulty TXV would not typically cause the compressor to fail to engage. The root issue here is the lack of an A/C request signal, which points more towards the electrical or control systems, rather than the refrigerant flow.
- Technician B’s suggestion: The engine cooling system thermostat controls the engine’s operating temperature by regulating coolant flow. While a thermostat that opens too soon could cause the engine to run cooler than normal, it would not directly affect the A/C system’s ability to engage. The A/C system has its own set of controls, and although engine temperature does play a role in overall vehicle systems, it is not the cause of the lack of an A/C request signal. The issue here is more likely tied to the A/C control module or sensor.
In conclusion, the problem of the compressor not engaging due to the lack of an A/C request signal is more likely related to issues with the electrical system or sensors that communicate with the A/C control system, not the thermostatic expansion valve or the engine cooling system thermostat. Therefore, neither Technician A nor Technician B is correct.