Blast chiller Service Manual
23
Rev 07/04/2015
3.9. REFRIGERANT PRESSURES CHECKS
High or Low refrigerant pressure levels are dependent on:
• Ambient temperature
• Heat load in the cabinet (Full or Empty)
• Status of the cycle (hot food, frozen food etc.)
• Cabinet temperature
• TX valve regulation
• Evaporator coil air flow
• Condenser coil air flow
Checking the High and Low pressures on the unit alone cannot determine if the unit is
operating correctly. Careful analysis, based on the conditions listed above, is necessary to
properly diagnose a problem.
For example: Checking the suction pressure results in a reading of 0.1 barg. This could be
the correct pressure if the cabinet temperature is at the minimum (-40°C) and the
evaporator temperature is at -45°C.
If this is not the case, the evaporator may not be getting sufficient refrigerant and the
actual evaporator temperature could be much higher than -45°C. It is not recommended to
base any troubleshooting conclusions solely on the pressure readings.
SUCTION PRESSURE: 0.1/0.2 barg
This pressure should be measured when the cabinet temperature is at -40°C with the
compressor running.
DISCHARGE PRESSURE: 16 barg
This pressure can vary greatly and can reach up to 25 barg psig, depending on the
ambient temperature and heat load inside the cabinet. Very high discharge pressures can
cause the pressure switch to signal an alarm.
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