Troubleshooting: Cooling Sequence Of Operation - Lennox MERIT ML180UHE Installation Instructions Manual

Troubleshooting: Cooling Sequence of Operation

NORMAL COOLING MODE
IGNITION CONTROL MAIN POWER ON.
CONTROL SELF DIAGNOSTIC CHECK.
IS CONTROL OPERATING NORMALLY?
IS THERE A PROPER GROUND?
IS POLARITY CORRECT?
ABOVE 70 VOLTS?
ROLLOUT SWITCH MONITORED CONTINUOUSLY.
IS ROLLOUT SWITCH CLOSED?
LED: SLOW FLASH RATE REMAINS UNCHANGED
THROUGHOUT COOLING CYCLE.
THERMOSTAT CALLS FOR COOLING.
COMPRESSOR CONTACTOR AND SYSTEM FAN
ENERGIZED WITH 2-SECOND DELAY
(COOLING SPEED). EAC TERM. ENERGIZED.
THERMOSTAT OPENS.
COMPRESSOR OFF.
SYSTEM FAN AND EAC TERM. OFF
WITH 45-SECOND DELAY.
COOLING SEQUENCE OF OPERATION
POWER ON
YES
YES
YES
NO
IS VOLTAGE
YES
YES
ABNORMAL COOLING MODE
GAS VALVE OFF. COMBUSTION AIR INDUCER OFF.
NO
INDOOR BLOWER OFF WITH NORMAL DELAY.
SIGNAL CIRCUIT BOARD FAILURE AT LED.
INTERRUPT MAIN POWER TO RESET CONTROL.
NO
LED FLASHES CODE 2 IMPROPER GROUND
CONTROL WILL CONTINUE TO CALL FOR COOLING
IN THIS CONDITION.
NO
LED FLASHES CODE 1 POLARITY REVERSED
CONTROL WILL CONTINUE TO CALL FOR COOLING IN
THIS CONDITION.
LED FLASHES CODE 13 LOW VOLTAGE. CONTROL
WILL CONTINUE TO CALL FOR COOLING
IN THIS CONDITION.
LED FLASHES CODE 8 ROLLOUT SWITCH OPEN. GAS
NO
VALVE OFF. COMBUSTION AIR INDUCER ON. INDOOR
BLOWER ON. SEQUENCE HOLDS UNTIL ROLLOUT SWITCH
CLOSES AND MAIN POWER IS INTERRUPTED OR
THERMOSTAT IS CYCLED OFF/ON FOR 1 SEC. MINIMUM.
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