Abstract: An HVAC system includes a suction-side sensor, a liquid-side sensor, an outdoor temperature sensor, and a controller. The controller determines that initial criteria are satisfied for initiating validation of the suction-side sensor and the liquid-side sensor. After determining that the initial criteria are satisfied, a suction-side property value, liquid-side property value, and outdoor temperature value are received. The controller determines whether a first validation criteria and a second validation criteria are satisfied. If both the first validation criteria and the second validation criteria are satisfied, the suction-side sensor, the liquid-side sensor, and the outdoor temperature sensor are determined to be functioning properly. Otherwise, the controller determines which one or more of the sensors are malfunctioning.

Abstract: A controller of an HVAC system monitors a suction-side property and a liquid-side property over a period of time. The controller determines whether the suction-side property has an increasing or decreasing trend over the period of time. The controller determines whether the liquid-side property has an increasing or decreasing trend. In response to determining that both the suction-side property and the liquid-side property have an increasing trend over the period of time, a fan fault is detected. In response to determining that the suction-side property has a decreasing trend and the liquid-side property has an increasing trend over the period of time, a blockage of a refrigerant conduit subsystem is detected. In response to determining that both the suction-side property and the liquid-side property have a decreasing trend over the period of time, a blower fault is detected.

Abstract: An HVAC system includes a reversing valve configured to receive refrigerant and direct the received refrigerant based on an operating mode of the HVAC system. A sensor measures a heat-exchanger temperature associated with an outdoor heat exchanger. A controller monitors an outdoor temperature and the heat-exchanger temperature and compares these temperatures. The controller determines whether the HVAC system is intended to operate in a cooling or heating mode. If the heat-exchanger temperature is less than the outdoor temperature and the HVAC system is intended to operate in the cooling mode, the controller determines that a first reversing-valve fault is detected. The first reversing-valve fault is associated with the reversing valve being in the heating configuration when the HVAC system is intended to operate in the cooling mode.

Abstract: A controller of an HVAC system is communicatively coupled to a liquid-side sensor and a shutoff switch. The controller stores measurements of a liquid-side property over an initial period of time. The controller detects that the shutoff switch is tripped at a first time stamp corresponding to an end of the initial period of time. The controller accesses the measurements of the liquid-side property. The controller determines, based on the measurements of the liquid-side property, that the liquid-side property has an increasing trend. In response to determining that the liquid-side property has the increasing trend, a blockage of the refrigerant conduit subsystem is determined to have caused the shutoff switch to trip.

Abstract: A controller of an HVAC system is communicatively coupled to a liquid-side sensor and a shutoff switch. The controller stores measurements of a liquid-side property over an initial period of time. The controller detects that the shutoff switch is tripped at a first time stamp corresponding to an end of the initial period of time. The controller accesses the measurements of the liquid-side property. The controller determines, based on the measurements of the liquid-side property, that the liquid-side property has a decreasing trend. In response to determining that the liquid-side property has the decreasing trend, a malfunction of a blower of the system is determined to have caused the shutoff switch to trip.

Abstract: An HVAC system includes a reversing valve configured to receive compressed refrigerant and direct the refrigerant based on an operating mode. One or more suction-side sensors measure suction-side properties associated with refrigerant, including a suction-side temperature and a suction-side pressure. One or more liquid-side sensors measure liquid-side properties associated with the refrigerant. A controller monitors the suction-side pressure and liquid-side pressure and determines a ratio of the liquid-side pressure to the suction-side pressure. The controller further determines whether the suction-side temperature has an increasing trend. If the suction-side temperature has the increasing trend, the reversing valve is determined to be in an equalizing configuration. The equalizing configuration corresponds to a configuration in which the refrigerant provided from the outlet of the compressor is directed to the inlet of the compressor without first being directed to other components of the HVAC system.

Abstract: A controller of an HVAC system is communicatively coupled to a suction-side sensor and a shutoff switch. The controller stores measurements of the suction-side property over an initial period of time. The controller detects that the shutoff switch is tripped at a first time stamp corresponding to an end of the initial period of time. The controller accesses the measurements of the suction-side property. The controller determines, based on the measurements of the suction-side property, whether the suction-side property has an increasing or decreasing trend. In response to determining that the suction-side property has the increasing trend, the controller determines that a malfunction of a fan caused the shutoff switch to trip. In response to determining that the suction-side property has the decreasing trend, the controller determines that a blockage of the refrigerant conduit subsystem caused the shutoff switch to trip.

Abstract: An HVAC system includes a controller communicatively coupled to a subcool sensor, an outdoor temperature sensor, a compressor, and a blower of the HVAC system. For a first period of time, the controller periodically determines subcool values. For each determined subcool value, a corresponding compressor speed, outdoor temperature, and blower speed are determined. A baseline database is generated with baseline values associated with normal operation of the HVAC system. Following the first period of time, subcool values are determined based on the subcool signal. For each subcool value, a corresponding compressor speed, outdoor temperature, and blower speed are determined. The controller determines whether each subcool value satisfies a criteria based on the baseline database. If the criteria are not satisfied for at least a threshold time, the system is determined to be operating under a fault condition, and a corresponding alert is transmitted.

Abstract: An HVAC system includes a suction-side sensor, a liquid-side sensor, an outdoor temperature sensor, and a controller. The controller determines that initial criteria are satisfied for initiating validation of the suction-side sensor and the liquid-side sensor. After determining that the initial criteria are satisfied, a suction-side property value, liquid-side property value, and outdoor temperature value are received. The controller determines whether a first validation criteria and a second validation criteria are satisfied. If both the first validation criteria and the second validation criteria are satisfied, the suction-side sensor, the liquid-side sensor, and the outdoor temperature sensor are determined to be functioning properly. Otherwise, the controller determines which one or more of the sensors are malfunctioning.

Abstract: A controller of an HVAC system is communicatively coupled to a suction-side sensor and a shutoff switch. The controller stores measurements of the suction-side property over an initial period of time. The controller detects that the shutoff switch is tripped at a first time stamp corresponding to an end of the initial period of time. The controller accesses the measurements of the suction-side property. The controller determines, based on the measurements of the suction-side property, whether the suction-side property has an increasing or decreasing trend. In response to determining that the suction-side property has the increasing trend, the controller determines that a malfunction of a fan caused the shutoff switch to trip. In response to determining that the suction-side property has the decreasing trend, the controller determines that a blockage of the refrigerant conduit subsystem caused the shutoff switch to trip.

Abstract: An HVAC system includes a reversing valve configured to receive refrigerant and direct the received refrigerant based on an operating mode of the HVAC system. A sensor measures a heat-exchanger temperature associated with an outdoor heat exchanger. A controller monitors an outdoor temperature and the heat-exchanger temperature and compares these temperatures. The controller determines whether the HVAC system is intended to operate in a cooling or heating mode. If the heat-exchanger temperature is less than the outdoor temperature and the HVAC system is intended to operate in the cooling mode, the controller determines that a first reversing-valve fault is detected. The first reversing-valve fault is associated with the reversing valve being in the heating configuration when the HVAC system is intended to operate in the cooling mode.

Abstract: A controller of an HVAC system monitors a suction-side property and a liquid-side property over a period of time. The controller determines whether the suction-side property has an increasing or decreasing trend over the period of time. The controller determines whether the liquid-side property has an increasing or decreasing trend. In response to determining that both the suction-side property and the liquid-side property have an increasing trend over the period of time, a fan fault is detected. In response to determining that the suction-side property has a decreasing trend and the liquid-side property has an increasing trend over the period of time, a blockage of a refrigerant conduit subsystem is detected. In response to determining that both the suction-side property and the liquid-side property have a decreasing trend over the period of time, a blower fault is detected.

Abstract: A controller of an HVAC system is communicatively coupled to a suction-side sensor and a shutoff switch. The controller stores measurements of the suction-side property over an initial period of time. The controller detects that the shutoff switch is tripped at a first time stamp corresponding to an end of the initial period of time. The controller accesses the measurements of the suction-side property. The controller determines, based on the measurements of the suction-side property, whether the suction-side property has an increasing or decreasing trend. In response to determining that the suction-side property has the increasing trend, the controller determines that a malfunction of a fan caused the shutoff switch to trip. In response to determining that the suction-side property has the decreasing trend, the controller determines that a blockage of the refrigerant conduit subsystem caused the shutoff switch to trip.

Abstract: An HVAC system includes a reversing valve configured to receive refrigerant and direct the received refrigerant based on an operating mode of the HVAC system. The HVAC system includes first and second sensors. A sensor measures a heat-exchanger temperature associated with the outdoor heat exchanger. A controller monitors an outdoor temperature and the heat-exchanger temperature and compares these temperatures. The controller determines whether the HVAC system is intended to operate in a cooling or heating mode. If the heat-exchanger temperature is less than the outdoor temperature and the HVAC system is intended to operate in the cooling mode, the controller determines that a first reversing-valve fault is detected. The first reversing-valve fault is associated with the reversing valve being in the heating configuration when the HVAC system is intended to operate in the cooling mode.

Abstract: A controller of an HVAC system monitors a suction-side property and a liquid-side property over a period of time. The controller determines whether the suction-side property has an increasing or decreasing trend over the period of time. The controller determines whether the liquid-side property has an increasing or decreasing trend. In response to determining that both the suction-side property and the liquid-side property have an increasing trend over the period of time, a fan fault is detected. In response to determining that the suction-side property has a decreasing trend and the liquid-side property has an increasing trend over the period of time, a blockage of a refrigerant conduit subsystem is detected. In response to determining that both the suction-side property and the liquid-side property have a decreasing trend over the period of time, a blower fault is detected.

Abstract: An HVAC system includes a reversing valve configured to receive compressed refrigerant and direct the refrigerant based on an operating mode. One or more suction-side sensors measure suction-side properties associated with refrigerant, including a suction-side temperature and a suction-side pressure. One or more liquid-side sensors measure liquid-side properties associated with the refrigerant. A controller monitors the suction-side pressure and liquid-side pressure and determines a ratio of the liquid-side pressure to the suction-side pressure. The controller further determines whether the suction-side temperature has an increasing trend. If the suction-side temperature has the increasing trend, the reversing valve is determined to be in an equalizing configuration. The equalizing configuration corresponds to a configuration in which the refrigerant provided from the outlet of the compressor is directed to the inlet of the compressor without first being directed to other components of the HVAC system.

Abstract: A controller of an HVAC system is communicatively coupled to a liquid-side sensor and a shutoff switch. The controller stores measurements of a liquid-side property over an initial period of time. The controller detects that the shutoff switch is tripped at a first time stamp corresponding to an end of the initial period of time. The controller accesses the measurements of the liquid-side property. The controller determines, based on the measurements of the liquid-side property, that the liquid-side property has a decreasing trend. In response to determining that the liquid-side property has the decreasing trend, a malfunction of a blower of the system is determined to have caused the shutoff switch to trip.

Abstract: A controller of an HVAC system is communicatively coupled to a liquid-side sensor and a shutoff switch. The controller stores measurements of a liquid-side property over an initial period of time. The controller detects that the shutoff switch is tripped at a first time stamp corresponding to an end of the initial period of time. The controller accesses the measurements of the liquid-side property. The controller determines, based on the measurements of the liquid-side property, that the liquid-side property has an increasing trend. In response to determining that the liquid-side property has the increasing trend, a blockage of the refrigerant conduit subsystem is determined to have caused the shutoff switch to trip.

Abstract: A controller of an HVAC system is communicatively coupled to a liquid-side sensor and a shutoff switch. The controller stores measurements of a liquid-side property over an initial period of time. The controller detects that the shutoff switch is tripped at a first time stamp corresponding to an end of the initial period of time. The controller accesses the measurements of the liquid-side property. The controller determines, based on the measurements of the liquid-side property, whether the liquid-side property has an increasing or a decreasing trend. In response to determining that the liquid-side property has the decreasing trend, a malfunction of a blower of the system is determined to have caused the shutoff switch to trip. In response to determining that the liquid-side property has the increasing trend, a blockage of the refrigerant conduit subsystem is determined to have caused the shutoff switch to trip.

Abstract: An HVAC system includes a reversing valve configured to receive compressed refrigerant and direct the refrigerant based on an operating mode of the HVAC system. One or more suction-side sensors measure suction-side properties associated with refrigerant provided to an inlet of the compressor. The suction-side properties comprise a suction-side temperature. One or more liquid-side sensors measure liquid-side properties associated with the refrigerant provided from an outlet of the compressor. A controller monitors the suction-side property and liquid-side property. The controller determines whether the suction-side property is greater than the liquid-side property. If the suction-side temperature is greater than the liquid-side temperature, the reversing valve is determined to be in an equalizing configuration.