May 2015 Tech Challenge


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A medium temperature cooler utilizing R-134a with a fixed orfice (capillary tube) feed device has a customer complaint of “warm product.” The symptoms at the convenience store confirm warm product and the condensing unit appears to be cycling on the low or high pressure control. What are the “possible causes” with the following measured conditions on this field service check sheet?

Field Service Check Sheet

Compressor Discharge Temp. 200 deg. F.
Condensing Press./Temp. 112 psig / 94 deg. F.
Condensing Outlet Temp. 78 deg. F.
Condenser Sub cooling 16 deg. F.
Condenser Split 19 deg. F.
Entering Feed Device Temp. 44 deg. F.
Evaporator Press./Temp. 5 psig / -3deg. F.
Evaporator Outlet Temp. 37 deg. F.
Evaporator Superheat 40 deg. F.
Compressor Inlet Temp. 68 deg. F.
Total S. H. 71 Deg. F.
Ambient Temp. 75 deg. F.
Room/Box Temp. 50 deg. F.
Compressor Volts 240 V.
Compressor Amp. Draw Low

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


Posted In: ACCA Now, Tech Challenge

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