25
Dual 7-Segment
LEDs Display
Code
Diagnostic Description
Status/Possible Cause – Troubleshooting
Information
06 – Compressor Open Start Circuit
The ICC detects current in the Run
circuit but not in the Start circuit of the
compressor four (4) times in one
compressor call
• Check for damaged, miswired, or wrong
run capacitor
• Check for broken wires, loose connectors,
or miswired compressor
• Check compressor windings for continuity
05 – Open circuit (Compressor will not
Run)
• The ICC has had a protector trip for longer
than 4 hours
• Check for damaged, miswired, or wrong run
capacitor
• Check for broken wires, loose connectors, or
miswired compressor
• Check compressor windings for continuity
• Check for open compressor internal protector
06 – Compressor Open Start Circuit
The ICC detects current in the Run circuit
but not in the Start circuit of the compressor
• Check for damaged, miswired, or wrong run
capacitor
• Check for broken wires, loose connectors, or
miswired compressor
• Check compressor windings for continuity
07 – Compressor Open Run Circuit
The ICC detects current in the Start
circuit but not in the Run circuit of the
compressor four (4) times in one
compressor call
• Check for damaged, miswired, or wrong
run capacitor
• Check for broken wires, loose connectors,
or miswired compressor
• Check compressor windings for continuity
07 – Compressor Open Run Circuit
The ICC detects current in the Start circuit
but not in the Run circuit of the compressor
• Check for damaged, miswired, or wrong run
capacitor
• Check for broken wires, loose connectors, or
miswired compressor
• Check compressor windings for continuity
09 – Low Secondary Volts
The secondary voltage at R and C is below
18VAC
• Control transformer overloaded
• Low line voltage
21 – Low Pressure Control Open
The ICC detects the LPC is open.
Note: The low pressure control is ignored
for the first 90 seconds of compressor
operation
• Unit has low refrigerant charge
• Indoor coil is frozen (cooling mode)
• Dirty indoor coil or filter (cooling mode)
• Indoor blower is not running (cooling mode)
• Outdoor coil is frozen (heating mode)
• Expansion valve is not operating correctly
L21 –
Active Protection
Low Pressure
Control Trip
LPC has opened 3 times in the same cooling
operation, the ICC has locked out the compressor
to protect it. ICC alternately flashes L and 21
FLASHING
L
27 – Low Line Voltage or No Line Voltage
Fault
• Check incoming line voltage to the disconnect
and unit
• Check wiring connections
28 – High Line Voltage Fault
• Check line voltage
