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September 2023 Tech Challenge


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A logo of a yellow, red, blue, and green rubix cube with one square out of place and "Tech Challenge" written beneath it

Share this challenge with your staff and see who can figure out the diagnosis first.

A frozen food case utilizing R-404A with a TXV metering device (and receiver) has a customer complaint of “warm case.” The symptoms at the store confirm that the case is 20 degrees warmer than normal, and the condensing unit is running continuously. What are the “possible causes” (note: there is only one problem intended) with the following measured conditions on this field service check sheet? 

Note: There is only one problem intended.

Field Service Check Sheet 

  • Compressor Discharge Temp. 225 deg. F.
  • Condensing Press./Temp. 187 psig / 84 deg. F. 
  • Condensing Outlet Temp. 81 deg. F. 
  • Condenser Subcooling 3 deg. F. 
  • Condenser Split 14 deg. F. 
  • Entering Feed Device Temp. 78 deg. F. 
  • Evaporator Press./Temp. 15 psig / -22 deg. F. 
  • Evaporator Outlet Temp. 12 deg. F. 
  • Evaporator Superheat 32 deg. F. 
  • Compressor Inlet Temp. 48 deg. F. 
  • Total S. H. 54 deg. F. 
  • Ambient Temp. 70 deg. F. 
  • Room/Box Temp. 20 deg. F. 

Check back during the first week of October for the answer!

Dick Shaw
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Posted In: ACCA Now, Tech Challenge

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