Heating, Ventilation, and Air Conditioning (HVAC ) Electrical Practice Test

In an A/C schematic, which component would typically need replacing if the blower motor fails?

1. The compressor

2. The blower motor relay

3. The condenser fan motor

4. The thermostat

The correct answer is: The blower motor relay

In an A/C schematic, if the blower motor fails, it is often necessary to examine the blower motor relay since it is responsible for controlling the power to the blower motor. When the relay malfunctions, it can lead to the blower motor not receiving the necessary electrical signal to operate, which might mimic a blower motor failure. Therefore, if the blower motor is not running, checking the blower motor relay is a crucial step in diagnosing the issue. While other components like the compressor, condenser fan motor, or thermostat are vital to the overall system, they serve different functions. The compressor is responsible for circulating refrigerant, the condenser fan motor aids in cooling the refrigerant by expelling heat outside, and the thermostat regulates the system based on temperature settings. These components would not directly affect the operation of the blower motor and are less likely to be the root cause of a failure in that specific area. Focusing on the blower motor relay is a logical step when troubleshooting blower motor failures, as it plays a direct role in the motor's function.