Tech Challenge – September 2021
A medium temperature beer cooler utilizing R-134a with a TXV metering device and liquid receiver, has a customer complaint of warm beer. The symptoms at the convenience store confirm inadequate cooling and the compressor appears to be short cycling on the high- or low-pressure control. What are the “possible causes,” (Note: There is only one problem intended) with the following measured/calculated conditions on this field service check sheet?
Field Service Check Sheet
- Compressor Discharge Temp. 225 deg. F.
- Condensing Press. /Temp. 255 psig / 88 deg. F.
- Condensing Outlet Temp. 88 deg. F.
- Condenser Sub cooling 30 deg. F.
- Condenser Split 43 deg. F.
- Entering Feed Device Temp. 85 deg. F.
- Evaporator Press. /Temp. 22 psig / 25 deg. F.
- Evaporator Outlet Temp. 40 deg. F.
- Evaporator Superheat 15 deg. F.
- Compressor Inlet Temp. 68 deg. F.
- Total S. H. 43 deg. F.
- Ambient Temp. 75 deg. F.
- Room/Box Temp. 50 deg. F.
- Compressor Volts 240 V.
- Compressor Amp. Draw Normal/High
Check back on October 1, 2021 for the answer to this issue’s Tech Challenge.
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