Thermo King 098916, Maintenance Manual

Page: 177 / 196

Diagnosis: Troubleshooting, Status Messages, Alarm Codes
176
35 Ambient Air Sensor Short Circuit
(Check Alarm)
• Occurs during pretrip (PTI) test only.
• Sensor circuit resistance is lower than 200 ohms.
• Temperature is above 80 C (176 F).
• Indicates:
• Short circuit to sensor
• Defective or wrong sensor
• Defective relay board
• Defective cable No. 1
• Defective controller
• Check sensor resistance between pins 13 and
14 on plug J15. Resistance must be 2,000
ohms at 25 C (77 F).
• Check cable No. 1 between controller and
relay board.
43 Return Air temperature Too High
(Check Alarm)
• During defrost: Return air temperature increases
above 40 C (104 F).
• Indicates:
• Defective return or evaporator coil sensor.
• Return and evaporator coil sensor connections are
reversed.
• Check for sensor alarm codes.
• Check supply and return sensor connections
and locations.
51 Low Supply Voltage
(Check Alarm)
• Alarm occurs if line voltage is below 350 volts for 30
minutes
• If the main power supply voltage to the unit, while
running, drops below 340 VAC, the unit will stop
running until the voltage increases above 350
VAC. If the main power supply voltage, on initial
unit start up, is below 350 VAC, the unit will not
start. If the voltage remains below 350 VAC for 30
minutes, Alarm 51 (Low Voltage) will occur.
• Check line voltage of power source.
Refer to the electrical specifications in the
Specifications Section for correct power
source requirements.
53 High Pressure Cutout Switch Off Error
(Check Alarm)
• Occurs during pretrip (PTI) test only.
• Compressor does not stop during high pressure
cutout switch test.
• Indicates:
• Faulty compressor contactor or control circuit
• Low refrigerant charge
• Defective high pressure cutout switch
• Strong winds causing cooling of condenser coil in
low ambient conditions
• Check discharge and suction pressure gauge
readings and check refrigerant charge.
• Enter Manual Function Test menu. Start the
following components together: compressor
100 percent, compressor and evaporator fans
(high). Discharge pressure should increase
and compressor should stop at 2250 kPa, 22.5
bar, 326 psig (high pressure cutout switch
opens).
Alarm Codes, Descriptions and Corrective Actions (Continued)
Code Description Corrective Action