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March 2015 Tech Challenge

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A frozen food case utilizing R-404A with a TXV metering device (and receiver) has a customer complaint of a “warm case.” The symptoms at the store confirm that the case is 25 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?

Field Service Check Sheet

Compressor Discharge Temp. 230 deg. F.
Condensing Press./Temp. 181 psig / 82 deg. F.
Condensing Outlet Temp. 80 deg. F.
Condenser Sub cooling 2 deg. F.
Condenser Split 12 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.
Compressor Volts 240 V.
Compressor Amp. Draw Low

Looking for the answer? Check on April 30, 2015 for the answer to this issue’s Tech Challenge.

Posted In: ACCA Now, Tech Challenge

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