November 2015 Tech Challenge


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A frozen food case utilizing R-22 with a TXV metering device (and receiver) has a customer complaint of “soft product.” The symptoms at the store confirm that the case is 20 degrees warmer and the condensing unit appears to be cycling on the low pressure control. What are the possible causes (there is only one problem intended) with the following measured conditions on this field service check sheet?

Field Service Check Sheet

Compressor Discharge Temp. 90 deg. F.
Condensing Press./Temp. 165 psig / 89 deg. F.
Condensing Outlet Temp. 81 deg. F.
Condenser Sub cooling 8 deg. F.
Condenser Split 14 deg. F.
Entering Feed Device Temp. 77 deg. F.
Evaporator Press./Temp. 21 psig / -4 deg. F.
Evaporator Outlet Temp. -3 deg. F.
Evaporator Superheat 1 deg. F.
Compressor Inlet Temp. 0 deg. F.
Total S. H. 4 Deg. F.
Ambient Temp. 75 deg. F.
Room/Box Temp. 20 deg. F
Compressor Volts 240 V.
Compressor Amp. Draw Normal

Looking for the answer? Check hvac-blog.acca.org on December 31, 2015 for the answer to this Tech Challenge.

 


Posted In: ACCA Now, Tech Challenge

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