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Table 1. Interpreting the Diagnostic LEDS
Status LED
Status LED
Description
Status LED Troubleshooting Information
POWER
(Green LED)
Module has power
Supply voltage is present at module terminals
TRIP
(Red LED)
Thermostat demand
signal Y is present,
but compressor is not
running
• Compressor protector is open
• Check for high head pressure
• Check compressor supply voltage
• Outdoor unit power disconnect is open
• Compressor circuit breaker or fuse(s) is open
• Broken wire or connector is not making contact
• Low pressure switch open if present in system
• Compressor contactor has failed open
ALERT
Flash Code 1
(Yellow LED)
Long Run Time
Compressor is running
extremely long run
cycles
• Low refrigerant charge
• Evaporator blower is not running
• Evaporator coil is frozen
• Faulty metering device
• Condenser coil is dirty
• Liquid line restriction (filter drier blocked if present in system)
• Thermostat is malfunctioning
• Comfort Alert failure
ALERT
Flash Code 2
(Yellow LED)
System Pressure Trip
• High head pressure
Discharge or suction
• Condenser coil poor air circulation (dirty, blocked, damaged)
Pressure out of limits
• Condenser fan is not running
Compressor overloaded
• Return air duct has substantial leakage
• If low pressure switch present in system, check Flash Code 1
information
ALERT
Flash Code 3
(Yellow LED)
Short Cycling /
Compressor is running
only briefly
• Thermostat demand signal is intermittent
• Low line voltage (contact utility if voltage at disconnect is low)
• Excessive liquid refrigerant in compressor
• Compressor bearings are seized
ALERT
Flash Code 4
(Yellow LED)
Locked Rotor
• Run capacitor has failed
• Low line voltage (contact utitlity if voltage at disconnect is low)
• Check wiring connections
• Excessive liquid refrigerant in compressor
• Compressor bearings are seized
• Measure compressor oil level
ALERT
Flash Code 5
(Yellow LED)
Open Circuit
• Outdoor unit power disconnect is open
• Compressor circuit breaker or fuse(s) is open
• Compressor contactor has failed open
• Open circuit in compressor supply wiring or connections
• Unusually long compressor protector reset time due to extreme
ambient temperature
• Compressor windings are damaged
ALERT
Flash Code 6
(Yellow LED)
Open Start Circuit
Current only in run
circuit
• Run capacitor has failed
• Open circuit in compressor start wiring or connections
• Compressor start winding is damaged
ALERT
Flash Code 7
(Yellow LED)
Open run circuit
Current only in start
circuit
• Open circuit in compressor run wiring or connections
• Compressor run winding is damaged
ALERT
Flash Code 8
(Yellow LED)
Welded Contactor
Compressor always
runs
• Compressor contactor has failed closed
• Thermostat demand signal not connected to module
ALERT
Flash Code 9
(Yellow LED)
Low Voltage
Control circuit <
17VAC
• Control circuit transformer is overloaded
• Low line voltage (contact utility if voltage at disconnect is low)
• Check wiring connections
* Flash code number corresponds to a number of LED flashes, followed by a pause and then repeated. Trip and alert LED’s
flashing at same time means control circuit voltage is too low for operation.
