US 11,719,452 B2
System and method for distinguishing HVAC system faults
Amita Brahme, Dallas, TX (US); and Umesh Gokhale, Irvng, TX (US)
Assigned to Lennox Industries Inc., Richardson, TX (US)
Filed by Lennox Industries Inc., Richardson, TX (US)
Filed on Oct. 20, 2021, as Appl. No. 17/451,531.
Application 17/451,531 is a continuation of application No. 16/806,274, filed on Mar. 2, 2020, granted, now 11,193,685.
Prior Publication US 2022/0034538 A1, Feb. 3, 2022
This patent is subject to a terminal disclaimer.
Int. Cl. F24F 11/38 (2018.01); F24F 140/12 (2018.01)
CPC F24F 11/38 (2018.01) [F24F 2140/12 (2018.01)] 20 Claims
OG exemplary drawing
 
1. A heating, ventilation and air conditioning (HVAC) system comprising:
a refrigerant conduit subsystem configured to allow a flow of refrigerant through the HVAC system;
a compressor configured to receive refrigerant and direct the refrigerant to flow through a refrigerant conduit subsystem;
an evaporator configured to receive the refrigerant and allow heat transfer between the refrigerant and a flow air across the evaporator;
a blower configured to provide the flow of air across the evaporator;
a suction-side sensor positioned and configured to measure a suction-side property associated with refrigerant provided to an inlet of the compressor, wherein the suction-side property comprises at least one of a suction-side temperature or a suction-side pressure;
a shutoff switch communicatively coupled to the suction-side sensor and configured to be tripped and automatically stop operation of the compressor and blower in response to determining that the suction-side property is less than a predefined minimum value;
a liquid-side sensor positioned and configured to measure a liquid-side property associated with the refrigerant provided from an outlet of the compressor, wherein the liquid-side property comprises at least one of a liquid-side temperature or a liquid-side pressure; and
a controller communicatively coupled to the shutoff switch and the liquid-side sensor, the controller configured to:
store measurements of the liquid-side property over an initial period of time;
detect that the shutoff switch is tripped at a first time stamp corresponding to an end of the initial period of time;
access the measurements of the liquid-side property;
determine, based on the measurements of the liquid-side property, that the liquid-side property has an increasing trend; and
in response to determining that the liquid-side property has the increasing trend, determine that a blockage of the refrigerant conduit subsystem caused the shutoff switch to trip.