Tech Challenge – September 2018
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A medium temperature cooler utilizing R-134a with a capillary tube feed device 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. | 210 deg. F |
| Condensing Press./Temp. | 108 psig / 92 deg. F. |
| Condensing Outlet | 76 deg. F. |
| Condenser Sub cooling | 16 deg. F. |
| Condenser Split | 17 deg. F. |
| Entering Feed Device Temp. | 44 deg. F. |
| Evaporator Press./Temp. | 5 psig / -3 deg. 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.34 | 50 deg. F |
| Compressor Volts | 240 V. |
| Compressor Amp. Draw | Low |
Looking for the Answer: Check hvac-blog.acca.org on October 31, 2018, for the answer to this issue’s Tech Challenge.
Posted In: ACCA Now, Tech Challenge
