22 Capacity Test 1 Error MP4000

Occurs during pretrip (PTI) test only.
Difference between supply and return air temperature is too small with high speed evaporator fans (less than approximately 4.5 C [8 F]).
When the return air temperature does not reach -18 C (0 F) within preset time.
Indicates:
Incorrect location of supply or return air sensor.
Air leakage at supply sensor cable.
Defective supply or return air sensor.
Interchanged sensor connections.
Incorrect evaporator fan rotation or high speed operation.
Incorrect refrigeration system operation.
Container/side panels defective, damaged or leaking.
Economizer circuit defective.

Enter Manual Function Test and start evaporator fans on high speed and let operate fans for 5 minutes. Check supply, return and evaporator coil (defrost) sensor temperatures. Sensor readings should be the same (evaporator coil may be 0.5 C [1.0 F] lower due to fan motor heat).
Open evaporator door and inspect evaporator fan rotation. Make sure fans are rotating correctly on high speed.
Check the sensor connections.
Enter Manual Function Test menu. Start and check current draw of the following components separately and together: compressor, vapor on, condenser fan and evaporator fans (high). Check discharge and suction pressure readings. Also check the refrigerant charge.

NOTE: This alarm can be activated in ambient temperatures below -10 C (14 F), even under normal conditions.

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