Detection of a reversing valve fault

A method of operating a heating, ventilation and air conditioning (HVAC) system, the method comprising:

• monitoring a first temperature corresponding to an outdoor temperature;
• monitoring a second temperature associated with an outdoor heat exchanger of the HVAC system;
• comparing the monitored first temperature to the monitored second temperature;
• determining whether the HVAC system is intended to operate in a cooling mode or heating mode;
• in response to determining that the second temperature is less than the first temperature and that the HVAC system is intended to operate in the cooling mode:
• determining that a first reversing-valve fault is detected, wherein the first reversing-valve fault is associated with the reversing valve being in a heating configuration when the HVAC system is intended to operate in the cooling mode;
• transmitting a signal instructing the reversing valve to change to an alternate position;
• following a predefined delay time after transmitting the signal, determining whether the second temperature is still less than the first temperature;
• in response to determining that the second temperature is no longer less than the first temperature, determining that the reversing-valve fault is resolved;
• and
• in response to determining that the second temperature is still less than the first temperature, determining that the reversing-valve fault is unresolved.

A controller of a heating, ventilation and air conditioning (HVAC) system, the controller comprising:

• an input/output interface configured to communicatively couple the controller to:
• a data source providing measurements of a first temperature corresponding to an outdoor temperature;
• and
• a sensor positioned and configured to measure a second temperature associated with an outdoor heat exchanger of the HVAC system;
• and
• a processor coupled to the input/output interface, the processor configured to:
• monitor, based on measurements received from the data source, the first temperature;
• monitor, based on measurements received from the sensor, the second temperature;
• compare the monitored first temperature to the monitored second temperature;
• determine whether the HVAC system is intended to operate in a cooling mode or heating mode;
• in response to determining that the second temperature is less than the first temperature and that the HVAC system is intended to operate in the cooling mode:
• determine that a first reversing-valve fault is detected, wherein the first reversing-valve fault is associated with the reversing valve being in a heating configuration when the HVAC system is intended to operate in the cooling mode;
• cause the input/output interface to transmit a signal instructing the reversing valve to change to an alternate position;
• following a predefined delay time after transmitting the signal, determine whether the second temperature is still less than the first temperature;
• in response to determining that the second temperature is no longer less than the first temperature, determine that the reversing-valve fault is resolved;
• and
• in response to determining that the second temperature is still less than the first temperature, determine that the reversing-valve fault is unresolved.