If the blower motor is not operational while the system seems to be running, which component failure could be responsible?

When the blower motor is not functioning while the system appears to be operational, the blower relay is a likely culprit. The blower relay acts as an electrical switch that controls the power supply to the blower motor. If the relay fails, it may not close the circuit necessary for the blower motor to receive electricity, preventing it from turning on despite the fact that the rest of the system may still be running.

In this scenario, it’s crucial to recognize that if the blower relay were to fail, the system could still operate in terms of managing refrigerant flow and maintaining pressure, which would make it appear functional at a surface level. Meanwhile, without the blower motor running, there’s no air circulation to facilitate heating or cooling, which is essential for the system's overall performance.

The other components mentioned might also affect the operation of the HVAC system, but their failure would typically not result in a situation where the system is running while the blower motor itself is completely inactive. For instance, the compressor relay is responsible for the compressor's operation, but a problem here doesn’t directly stop the blower motor; the same logic applies to capacitors and thermostats. Thus, focusing on the blower relay provides the most accurate diagnosis for this particular issue.