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 hvac-blog.acca.org on April 30, 2015 for the answer to this issue’s Tech Challenge.


Posted In: ACCA Now, Tech Challenge

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