MP-3000 Controller
117
24 Capacity Test 3 Error
(Check Alarm)
• Occurs during pre-trip (PTI) test only.
• Difference between supply and return air
temperature is too high with Stepper valve almost
closed and high speed evaporator fans (more than
1.5 C [2.7 F]).
• Indicates:
• Defective Stepper valve
• Incorrect location of supply or return air sensor
• Defective supply or return air sensor
• Expansion valve open too much
• Incorrect refrigeration system operation
• Container/side panels defective, damaged or
leaking
• Enter Manual Function Test and start the
following components: Condenser fan,
evaporator fan (high), compressor and
compressor 25%. Check to be sure the
Stepper valve closes.
• Check the supply and return air sensor
connections.
• Check the supply and return air sensor
calibration.
• Check expansion valve superheat setting.
25 Evaporator Temperature Test Error
(Check Alarm)
• Occurs during pre-trip (PTI) test only.
• Evaporator coil temperature is too high with no
evaporator fans running (above about -15 C [+5 F]).
• Indicates:
• Evaporator coil sensor is not in contact with
evaporator coil
• Return and evaporator coil sensor connections
are interchanged
• Expansion valve does not open enough or opens
too much
• Check evaporator coil sensor location.
• Check evaporator coil sensor and return air
sensor connections.
• Check expansion valve superheat setting.
27 Heat Capacity Test Error
(Check Alarm)
• Occurs during pre-trip (PTI) test only.
• Difference between supply and return air
temperature is too small with high speed
evaporator fans (less than 0.4 C [0.7 F]).
• Indicates:
• Incorrect location of supply or return air sensor
• Air leakage at supply, return or evaporator coil
sensor cable
• Defective supply or return air sensor
• Interchanged sensor connections
• Defective heater elements
• Incorrect evaporator fan rotation or high speed
operation
• Container/side panels defective, damaged or
leaking
• Enter Manual Function Test and start
evaporator fans on high speed. Then select
Sensor Checks test and operate fans 2 to 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).
NOTE: This sensor check does not detect
air leakage around the sensor cables.
• Open evaporator door and inspect evaporator
fan rotation. Make sure fans are rotating
correctly on high speed.
• Check the sensor connections.
Alarm Codes, Descriptions and Corrective Actions (Continued)
Code Description Corrective Action
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