High Economizer Superheat
refrigeration
Description
In economized mode, ECXV open above 99% for five minutes with box temperature less than 14°F (-10°C) and economizer superheat above 74°F (23°C) for five minutes, and the unit only alarms.
Activation Conditions
With unit running in economized mode for 15 minutes, ECXV open greater than 99% for five minutes, and a box temperature less than 14°F (-10°C); economizer superheat is above 74°F (23°C) for five minutes. NOTE This alarm can be caused by a stuck ECXV, not letting enough liquid into the economizer circuit. An inaccurate economizer pressure transducer or economizer temperature sensor can also cause this alarm.
Unit Behavior
Engine and Electric Operation: Alarm only.
Reset Conditions
Calculated economizer superheat reaches the desired range, or < 60°F (15°C) for two minutes. Unit Changes from Economized mode to Standard mode or Compressor shuts off, or alarm may be manually reset via keypad or by turning the unit off, then back on again. NOTICE Follow the steps below until a problem is found. Once a repair or correction has been made, clear the alarm(s). (Refer to Note 1 in Notes Section) Operate the unit through the appropriate modes to see if any active alarm occurs. Continue with the steps below as necessary.
Corrective Actions
1. Check for Low Refrigerant - Charge Check refrigerant level in the receiver. Generally, level should be between upper and lower sight glasses with a refrigerated compartment temperature of 35°F (1.0°C) or lower. refer to Section 8.6.2 2. Check Economizer Temperature Sensor - Inspect sensor and connectors. Verify there is no damage to sensor, and no damage, moisture, or corrosion in connectors. 3. Check Economizer Pressure Transducer - Inspect sensor and connectors. Verify there is no damage to sensor, and no damage, moisture, or corrosion in connectors. 4. Perform Pretrip - Run Pretrip and check for alarms. Any active alarms must be corrected and cleared before proceeding. 5. Check Economizer Expansion Valve (ECXV) a. Visually inspect valve. Verify there is no damage to valve, and no damage, moisture, or corrosion in coil. Check coil is seated properly. b. Check operation of valve. Refer to Section 8.8.8. 6. Check Expansion Valve (EVXV) a. Visually inspect valve. Verify there is no damage to valve, and no damage, moisture, or corrosion in coil. Check coil is seated properly. b. Check operation of valve. Refer to Section 8.8.8.