Alarm Codes, Descriptions And Corrective Actions - Thermo King MAGNUM Maintenance Manual

Diagnosis: Troubleshooting, Status Messages, Alarm Codes

Alarm Codes, Descriptions and Corrective Actions

NOTE: Sensors used with the MP-3000a
controller do not require calibration. Check
sensor resistance with an ohmmeter.
Alarm Codes, Descriptions and Corrective Actions
Code Description
00 Supply Air Sensor Open Circuit
(Check Alarm)
• When the sensor circuit resistance is higher than
100,000 ohms.
• When the temperature is below -70 C (-94 F).
• Indicates:
• Open circuit to left or right hand sensor
• Defective or wrong sensor
• Defective relay board
• Defective cable No. 1 or cable No. 3
• Defective controller
01 Supply Air Sensor Short Circuit
(Check Alarm)
• When the sensor circuit resistance is lower than
200 ohms.
• When the temperature is above 80 C (176 F).
• Indicates:
• Short circuit to left or right hand sensor Defective
or wrong sensor Defective relay board
• Defective cable No. 1 or cable No. 3
• Defective controller
02 Return Air Sensor Open Circuit
(Check Alarm)
• When the sensor circuit resistance is higher than
100,000 ohms.
• When the temperature is below -70 C (-94 F).
• Indicates:
• Open circuit to sensor
• Defective or wrong sensor
• Defective relay board
• Defective cable No. 1
• Defective controller
166
• Shutdown Alarm (Level 1 Alarm): Alarm
light on display flashes and unit stops. Correct
alarm condition and acknowledge alarm
before restarting.
• Check Alarm (Level 2 Alarm): Alarm light on
display flashes until alarm is acknowledged.
Corrective Action
• Identify defective sensor (left hand or right
hand) by viewing Data menu.
• Check sensor resistance between pins 1 and
2 on plug J15 and between pins 7 and 8 on
plug J14. Resistance must be 2,000 ohms at
25 C (77 F).
• Check cable No. 1 and cable No. 3 between
the controller and relay board.
• Check evaporator airflow.
• Identify defective sensor (left hand or right
hand) by viewing Data menu.
• Check sensor resistance between pins 1 and
2 on plug J15 and between pins 7 and 8 on
plug J14. Resistance must be 2,000 ohms at
25 C (77 F).
• Check cable No. 1 and cable No. 3 between
the controller and relay board.
• Check sensor resistance between pins 3 and
4 on plug J15. Resistance must be 2,000
ohms at 25 C (77 F).
• Check cable No. 1 between controller and
relay board.