4–37
T-372
4.10 Controller Alarm Indications
There are three alarm categories:
• AL0XX Refrigeration Critical Alarms
• AL2XX Refrigeration Non-Critical Alarms
• AL9XX Atmosphere Critical and Non-Critical Alarms
AL003
Loss of Superheat Control
Cause:
Superheat has remained below 1.66°C (3°F) degrees for five minutes continuously while compressor
running. Compressor drawing more than 2.0 amps, compressor pressure ratio is greater than 1.8,
and Electronic Expansion Valve (EEV) is at 0% open.
Component
Electronic Expansion Valve (EEV)
Troubleshooting
Check the operation of the EEV using Cd41.
Corrective Action
Replace EEV if defective.
Component
Evaporator Temperature Sensors (ETS1 & ETS2)
Troubleshooting
Verify accuracy of temperature sensors. See Sensor Checkout Procedure
Corrective Action
Replace ETS1 or ETS2 if defective.
Component
Evaporator Fans
Troubleshooting
Confirm fans operating properly.
Corrective Action
Replace fan(s) if defective. See Evaporator Fan Motor Assembly
AL017
Compressor Pressure Delta Failure
Cause:
Compressor has attempted to start in both directions and fails to generate sufficient pressure
differential between Suction Pressure Transducer (SPT) and Discharge Pressure Transducer (DPT).
Component
N/A
Troubleshooting
Controller will attempt to restart every 20 minutes and deactivate the alarm
if successful.
Corrective Action
Resume normal operation.
Component
Discharge Pressure Transducer (DPT)
Troubleshooting
Confirm accurate DPT pressure readings. See Manifold Gauge Set
Corrective Action
Replace DPT if defective.
Component
Suction Pressure Transducer (SPT)
Troubleshooting
Confirm accurate SPT pressure readings. See Manifold Gauge Set
Corrective Action
Replace SPT if defective.
Component
Monitor Unit
Troubleshooting
Alarm is display only; the alarm may clear itself during operation.
Corrective Action
If alarm remains active or is repetitive, replace compressor at next
available opportunity.
