Table of Contents
Status LED
Status LED Description
Green Alert LED
Module has power
Solid
Short Cycling
Green Alert LED
2 to 480 run cycles in 24hours ending
with normal
3 Flashes
Alert Default is set to 240 per 24 hours
Open Circuit
Green Alert LED
Demand signal is present but no
5 Flashes
compressor current for four hours
Welded Contactor
Green Alert LED
No demand signal, but current has
been detected in one or both phases
8 Flashes
Displayed for 24 hrs after last detection
Loss of Communication
Green Alert LED
Communication lost between rack
controller and module for 10 minutes or
10 Flashes
more
Green Alert LED
Discharge Temperature Sensor Error
Short or Open Circuit Detected
11 Flashes
Green Alert LED
Current Transducer (CT) Error
12 Flashes
Yellow Alert LED
Trip
Demand present, no current is detected
Solid
High Discharge Line Temperature Trip
Yellow Alert LED
See inside label to determine cut out
1 Flash
temp.
System Trip
Yellow Alert LED
Four consecutive compressor trips after
2 Flashes
run time of 1-15 minutes each
© 2012 Emerson Climate Technologies, Inc.
Printed in the U.S.A.
Application Engineering
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Diagnostics Module Troubleshooting
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Table 8
Status LED Troubleshooting Information
Supply voltage is present at module terminals
1. Check pressure or temperature control
2. Possible loss of refrigerant
3. Blocked Condenser
1. Compressor circuit breaker or fuse(s) is open
2. Compressor contactor has failed open
3. High pressure switch is open and requires
manual reset
4. Open circuit in compressor supply wiring or
connections
5. Long compressor protector reset time due to
high ambient temperature
6. Compressor windings are damaged
1. Contactor welded closed
2. Control circuit transformer is overloaded
3. Thermostat demand signal not connected to
module
4. Verify Wiring
1. Check communications wiring
2. Verify wiring follows application guidelines
1. Check discharge temperature sensor wiring
and mounting
2. Verify sensor is not shorted. 86k @ 77°F
1. Verify CT is plugged into module
2. Verify CT is not shorted
1. Compressor protector is open
- Check for high head pressure
- Check compressor supply voltage
2. Compressor circuit breaker or fuse(s) is open
3. Broken wire or connector is not making
contact
4. Safety cutout switches open (HPCO, LPCO,
OMB, etc.)
5. Compressor contactor has failed open
1. Possible loss of refrigerant charge
2. Blocked condenser
3. Verify that discharge valve is open
4. On low temperature scroll compressors check
liquid injection
1. Excessive suction pressure or discharge
pressure
2. Improper wiring
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