System and method for operating a packaged terminal air conditioner unit

Abstract

A packaged terminal air conditioner unit (PTAC) and methods for operating the same are provided. A PTAC controller is operably coupled to a compressor and an indoor fan for performing a cooling cycle. The compressor is stopped after the indoor temperature drops below a target temperature, but the indoor fan continues to circulate air through an indoor portion of the PTAC until a fan stop condition occurs. The fan stop condition occurs when the discharge temperature is at or above the dew point temperature to prevent condensation on components within the indoor portion of the PTAC.

What is claimed is: 
     
         1 . A packaged terminal air conditioner unit comprising:
 a bulkhead defining an indoor portion and an outdoor portion;   a refrigeration loop comprising an outdoor heat exchanger positioned within the outdoor portion and an indoor heat exchanger positioned within the indoor portion;   a compressor operably coupled to the refrigeration loop and being configured for urging a flow of refrigerant through the outdoor heat exchanger and the indoor heat exchanger;   an indoor fan configured for urging a flow of discharge air through the indoor heat exchanger and out a discharge vent; and   a controller operably coupled to the compressor and the indoor fan, the controller being configured for:
 operating the compressor and the indoor fan to lower an indoor temperature; 
 determining that the indoor temperature has dropped to a target room temperature; 
 stopping the compressor in response to determining that the indoor temperature has dropped to the target room temperature; 
 operating the indoor fan after stopping the compressor; and 
 stopping the indoor fan when a fan stop condition occurs. 
   
     
     
         2 . The packaged terminal air conditioner unit of  claim 1 , wherein the fan stop condition occurs when a predetermined amount of time has passed since stopping the compressor. 
     
     
         3 . The packaged terminal air conditioner unit of  claim 2 , wherein the predetermined amount of time is empirically determined by the controller. 
     
     
         4 . The packaged terminal air conditioner unit of  claim 1 , wherein the packaged terminal air conditioner unit further comprises:
 a discharge temperature sensor positioned within the indoor portion for measuring a discharge temperature; and   a humidity sensor positioned within the indoor portion for measuring an indoor humidity.   
     
     
         5 . The packaged terminal air conditioner unit of  claim 4 , wherein the controller is further configured for:
 obtaining a dew point temperature using the humidity sensor;   obtaining the discharge temperature using the discharge temperature sensor; and   determining that the fan stop condition occurs when the discharge temperature exceeds the dew point temperature.   
     
     
         6 . The packaged terminal air conditioner unit of  claim 4 , wherein the controller is further configured for:
 obtaining a dew point temperature using the humidity sensor;   determining an elevated target temperature based on the dew point temperature; and   determining that the fan stop condition occurs when the discharge temperature has exceeded the elevated target temperature.   
     
     
         7 . The packaged terminal air conditioner unit of  claim 6 , wherein the elevated target temperature is greater than the dew point temperature by at least 2 degrees Fahrenheit. 
     
     
         8 . The packaged terminal air conditioner unit of  claim 4 , wherein the humidity sensor is positioned within the indoor portion upstream of the indoor fan. 
     
     
         9 . The packaged terminal air conditioner unit of  claim 4 , wherein the discharge temperature sensor is positioned within the indoor portion proximate the discharge vent. 
     
     
         10 . The packaged terminal air conditioner unit of  claim 1 , further comprising an indoor temperature sensor for measuring the indoor temperature. 
     
     
         11 . A method of operating a packaged terminal air conditioner unit, the packaged terminal air conditioner unit comprising a compressor and an indoor fan, the method comprising:
 operating the compressor and the indoor fan to lower an indoor temperature;   determining that the indoor temperature has dropped to a target room temperature;   stopping the compressor in response to determining that the indoor temperature has dropped to the target room temperature;   operating the indoor fan after stopping the compressor; and   stopping the indoor fan when a fan stop condition occurs.   
     
     
         12 . The method of  claim 11 , wherein the fan stop condition occurs when a predetermined amount of time has passed since stopping the compressor. 
     
     
         13 . The method of  claim 12 , wherein the predetermined amount of time is empirically determined. 
     
     
         14 . The method of  claim 11 , further comprising:
 obtaining a dew point temperature using a humidity sensor;   obtaining a discharge temperature using a discharge temperature sensor; and   determining that the fan stop condition occurs when the discharge temperature exceeds the dew point temperature.   
     
     
         15 . The method of  claim 11 , further comprising:
 obtaining a dew point temperature using the humidity sensor;   obtaining a discharge temperature using a discharge temperature sensor;   determining an elevated target temperature based on the dew point temperature; and   determining that the fan stop condition occurs when the discharge temperature has exceeded the elevated target temperature.   
     
     
         16 . The method of  claim 15 , wherein the elevated target temperature is greater than the dew point temperature by at least 2 degrees Fahrenheit. 
     
     
         17 . An air conditioner unit comprising:
 a compressor configured for urging a flow of refrigerant through an outdoor heat exchanger and an indoor heat exchanger;   an indoor fan configured for urging a flow of discharge air through the indoor heat exchanger and out a discharge vent;   a discharge temperature sensor;   a humidity sensor; and   a controller operably coupled to the compressor and the indoor fan, the controller being configured for:
 operating the compressor and the indoor fan to lower an indoor temperature; 
 stopping the compressor when the indoor temperature drops below a target temperature; 
 obtaining a dew point temperature using the humidity sensor; 
 determining a fan stop temperature based on the dew point temperature; 
 obtaining a discharge temperature using the discharge temperature sensor; and 
 stopping the indoor fan when the discharge temperature exceeds the fan stop temperature. 
   
     
     
         18 . The air conditioner unit of  claim 17 , wherein the fan stop temperature is higher than the dew point temperature. 
     
     
         19 . The air conditioner unit of  claim 17 , wherein the humidity sensor is positioned upstream of the indoor fan. 
     
     
         20 . The air conditioner unit of  claim 17 , wherein the discharge temperature sensor is positioned proximate the discharge vent.