System and Method of Protecting an HVAC System

Abstract

Systems and methods are provided for operating a heating, ventilation, and/or air conditioning (HVAC) system that include recording a number of consecutive occasions in which a defrost mode is entered within a first predefined length of time after a heating cycle is entered, preventing operation of at least one component of the HVAC system for a second predefined length of time in response to entering the defrost mode a first predetermined consecutive number of occurrences within the first predefined length of time after a heating cycle is entered, recording a number of consecutive preventions of operation of the component of the HVAC system, and determining that a fault condition exists in the HVAC system in response to the number of consecutive temporary preventions of operation of the component of the HVAC system exceeding a second predefined number of occurrences.

What is claimed is: 
     
         1 . A method of operating a heating, ventilation, and/or air conditioning (HVAC) system, comprising:
 detecting a fault condition in response to the HVAC system to entering a defrost mode before a predefined threshold is reached for a predefined number of consecutive occasions; and   preventing operation of at least one component of the HVAC system for a predefined length of time in response to detecting the fault condition.   
     
     
         2 . The method of  claim 1 , further comprising:
 preventing operation of at least one component of the HVAC system until the fault condition is alleviated in response to detecting the fault condition a predefined number of fault condition occurrences.   
     
     
         3 . The method of  claim 1 , further comprising:
 incrementing a first counter in response to the HVAC system entering the defrost mode before the predefined threshold time.   
     
     
         4 . The method of  claim 3 , further comprising:
 incrementing a second counter in response to detecting the fault condition.   
     
     
         5 . The method of  claim 4 , further comprising:
 preventing operation of at least one component of the HVAC system in response to incrementing the second counter a predetermined number of times.   
     
     
         6 . The method of  claim 5 , wherein the predefined threshold comprises a predefined length of time after entering a heating cycle. 
     
     
         7 . The method of  claim 1 , wherein the predefined threshold comprises a rate of change of a difference between an ambient air temperature and an outdoor heat exchanger temperature. 
     
     
         8 . The method of  claim 1 , wherein the fault condition comprises at least one of:
 an air pressure drop across the outdoor heat exchanger;   a suction pressure; and   an outdoor fan power or current.   
     
     
         9 . The method of  claim 1 , further comprising:
 providing a notification of the fault condition.   
     
     
         10 . A heating, ventilation, and/or air conditioning (HVAC) system, comprising:
 a system controller configured to:   detect a fault condition in response to the HVAC system to entering a defrost mode before a predefined threshold is reached for a predefined number of consecutive occasions; and   prevent operation of at least one component of the HVAC system for a predefined length of time in response to detecting the fault condition.   
     
     
         11 . The HVAC system of  claim 10 , wherein the controller is further configured to prevent operation of at least one component of the HVAC system until the fault condition is alleviated in response to detecting the fault condition a predefined number of fault condition occurrences. 
     
     
         12 . The HVAC system of  claim 10 , wherein the controller comprises a first counter configured to increment each time the HVAC system enters the defrost mode before the predefined threshold time. 
     
     
         13 . The HVAC system of  claim 10 , wherein the controller comprises a second counter configured to increment each time the controller detects a fault condition. 
     
     
         14 . The HVAC system of  claim 13 , wherein the controller is configured to prevent operation of at least one component of the HVAC system in response to incrementing the second counter a predetermined number of times. 
     
     
         15 . The HVAC system of  claim 10 , wherein the predefined threshold comprises at least one of:
 a predefined length of time after entering a heating cycle;   a rate of change of a difference between an ambient air temperature and an outdoor heat exchanger temperature;   an air pressure drop across the outdoor heat exchanger;   a suction pressure; and   an outdoor fan power or current.   
     
     
         16 . The HVAC system of  claim 10 , wherein the controller is further configured to provide a notification of the fault condition. 
     
     
         17 . A method for operating a heating, ventilation, and/or air conditioning (HVAC) system, comprising:
 recording a number of consecutive occasions in which a defrost mode is entered within a first predefined length of time after a heating cycle is entered;   preventing operation of at least one component of the HVAC system for a second predefined length of time in response to entering the defrost mode a first predetermined consecutive number of occurrences within the first predefined length of time after a heating cycle is entered;   recording a number of consecutive preventions of operation of the component of the HVAC system; and   determining that a fault condition exists in the HVAC system in response to the number of consecutive temporary preventions of operation of the component of the HVAC system exceeding a second predefined number of occurrences.   
     
     
         18 . The method of  claim 17 , further comprising:
 preventing operation of at least one component of the HVAC system down until the fault condition is alleviated.   
     
     
         19 . The method of  claim 17 , further comprising:
 providing a notification of the fault condition.   
     
     
         20 . The method of  claim 17 , wherein the predetermined consecutive number of occurrences and the second predefined number of occurrences is three.