What happens to auxiliary heat during the defrost mode if there is a faulty defrost relay?

In a heat pump system, auxiliary heat is designed to provide additional warmth when the primary heating method (the heat pump) is not sufficient, such as during extremely cold weather. In the defrost mode, the heat pump temporarily reverses its operation to heat up the outdoor coil and melt any ice that has formed on it.

If there is a faulty defrost relay during this mode, the normal operation of the system is disrupted. The defrost relay is responsible for managing the transition into the defrost cycle, and if it fails, the heat pump may not switch to defrost mode as intended. In this situation, auxiliary heat is typically disabled to prevent unnecessary energy consumption and damages to the system.

Disabling the auxiliary heat helps to conserve energy and ensures that the system is not working against itself, as the primary heat is expected to manage the heating load during a properly functioning defrost cycle. If auxiliary heat were to engage without proper heat pump operation, it could lead to inefficient heating and potentially higher operating costs. Therefore, the correct effect of a faulty defrost relay is that auxiliary heat is disabled during the defrost mode.