When troubleshooting an A/C system, if the thermostat contacts are closed and the blower motor is not running, what could be the cause?

When troubleshooting an A/C system, if the thermostat contacts are closed, it indicates that the thermostat is signaling for the system to operate. However, if the blower motor is not running despite this signal, a common cause would indeed be a faulty blower motor or blower relay.

The blower motor is responsible for circulating the air through the system and into the living space. If the motor is malfunctioning, whether due to mechanical failure, electrical faults, or wear, it will not operate even when activated by the thermostat. Additionally, if the relay that controls the blower motor is faulty, it may not provide power to the motor, effectively preventing it from running.

Other options like a shorted compressor typically would not affect the blower motor's operation directly since the compressor is part of the refrigerant circuit and its issues usually affect cooling performance rather than fan function. A clogged filter could restrict airflow but wouldn’t prevent the motor from starting unless it were to overheat and burn out, which doesn’t explain a lack of any motor function from the start. An open capacitor could also cause the motor to fail to start, but this is often tied to specific motor designs that are reliant on capacitors to initiate operation. Therefore, while those scenarios are relevant to A/C