In a troubleshooting scenario where the thermostat contacts are closed, and the compressor and condenser fan motor are short cycling while the blower motor is not running, what could be the cause?

In the given scenario, the situation where the thermostat contacts are closed but the compressor and condenser fan motor are short cycling while the blower motor is not running indicates a problem with the airflow or control circuitry. The correct cause for this behavior is linked to a faulty blower motor or blower relay.

When the blower motor is not functioning, it means that there is no airflow through the system. This lack of airflow can lead to temperature imbalances that cause the compressor and condenser fan motor to short cycle. Short cycling occurs when the compressor and fan turn on and off rapidly, often as a protective measure in response to high-pressure conditions or inadequate cooling.

A faulty blower motor means that the air circulation necessary for heat exchange and proper system function is compromised. Similarly, a malfunctioning blower relay, which controls the operation of the blower motor, can prevent the motor from running when needed, leading to the same short cycling issue.

The closed contacts of the thermostat confirm that the system is trying to operate, but without the blower motor contributing to airflow, the system cannot maintain consistent operation. Therefore, the specific cause of the issue lies within the blower motor or its associated relay, which directly impacts the operation of the complete HVAC system.