T-372
4–48
AL910
Carbon Dioxide Sensor (CO2) Fault
Cause:
Triggered anytime the CO
2
sensor reading is outside of the normal operation range, after an initial
signal was detected.
Action:
Control O
2
to setpoint. Controlling O
2
may allow CO
2
to increase. Replace sensor as soon as
possible. If both AL909 and AL910 are active, run the EverFRESH Air Compressor (EAC) and open
the EverFRESH Air Valve (EA).
Component
CO
2
Sensor
Troubleshooting
Check wiring (refer to schematic), and check for bad connections or wires
improperly positioned.
Check the voltage on the back of MD connectors pin MD09 (-) and MD03
(+12 VDC) with the controller energized. If 12 VDC is not available, check
the controller. If 12 VDC is available, check the back of pin MD02 for a
voltage between 1.0 - 4.7 VDC. If not present, replace the sensor.
If part is available, remove the upper fresh air panel and evaporator motor
and replace the sensor. If no part is available, take no action and service
at next PTI.
AL929
Loss of Atmospheric Control
Cause:
Triggered whenever the CO
2
level is above its upper limit by 1% for 45 minutes. Or, when the O
2
level
is greater than 1% below its setpoint for longer than 30 minutes after the unit has been in range. The
alarm is triggered off when the levels return to within the normal range.
Action:
Enable Alarm LED. Open the fresh air vent and air compressor is enabled.
Setup
Verify all EverFRESH components are functioning properly by checking
for EverFRESH alarms and running a P-20 PreTrip.
Troubleshooting
If a component is not functioning properly, it will fail the appropriate P-20
sub test. Note components in order below.
Component
Membrane Pressure Transducer (MPT)
Troubleshooting
Remove the MPT. Turn on the container unit. Using Cd44, verify the MPT
pressure reads between -5 and +5 psig. Outside this range or if AL977
active, replace the sensor.
Component
EverFRESH Air Compressor (EAC)
Troubleshooting
Verify EAC fuses FEF1, FEF2 & FEF3.
Check P20 results for a failure mode:
• Possible detected failure with EAC current consumption, check
compressor motor windings, and verify voltage on all 3 phases.
• MPT failure. Follow steps above.
• Failure of AC contactor for EAC. Ohm contactor coil and check
resistance across contactor legs, with power removed.
Component
EverFRESH Air Valve (EA)
Troubleshooting
A closed or plugged EA solenoid could prevent fresh air from entering the
container. P20-2 tests the valve.
Potential failure results:
• MPT pressure fails to change when the valve is energized. Check
for signs of blockage in the valve or piping.
• EA current is not correct. Access function code Cd74 and perform
a ML5 self-check to verify the controller is functioning properly. If it
passes, perform a ohm check on the back of CA08 pin and TRX2
(ground) using the carrier service tool (part # 22-50485-00).
