Lennox G61MPV

Page 96
PROBLEM 1: UNIT FAILS TO OPERATE IN THE COOLING, HEATING, OR CONTINUOUS FAN MODE
Condition Possible Cause Corrective Action / Comments
1.5
− Diagnostic lights flash the improper
main ground.
LED#1−Alternating Fast Flash
LED#2−Alternating Fast Flash
1.5.1
Improper ground to the unit.
ACTION 1 − Check that the unit is properly
ground.
ACTION 2 − Install a proper main ground to the
unit
1.5.2
6−Pin connector is improperly
attached to the circuit board.
ACTION 1 − Check 6−pin connector for proper
installation. Correctly insert connector into con-
trol.
1.5.3
Line voltage is below 75V.
ACTION 1 − Check that the line voltage is above
75V. Determine cause of voltage drop and supply
correct voltage to the control.
1.5.4
Open ignitor circuit.
ACTION 1 − Check for correct wiring and loose
connections in the ignitor circuit. Check mult−plug
connections for correct installation.
1.5.5
Broken or failed ignitor.
ACTION 1 − Unplug ignitor and read resistance
across ignitor. If resistance does not read be-
tween 10.9 and 19.7 ohms, replace the ignitor.
PROBLEM 2: UNIT FAILS TO FIRE IN THE HEATING MODE, COMBUSTION AIR BLOWER DOES NOT
ENERGIZE
Condition Possible Cause Corrective Action / Comments
2.1
− Unit operates with a cooling or contin-
uous fan demand.
− Combustion air inducer will not start
with a Heating demand.
− Diagnostic lights flash the limit failure
mode.
LED#1−Slow Flash,
LED#2−On
2.1.1
Primary, secondary or backup secon-
dary (if equipped ) limit open.
ACTION 1 − Check continuity across switch(es).
Switches reset automatically upon cool down.
ACTION 2 − Check for restrictions on blower inlet
air (including filter) and outlet air. Determine
cause for limit activation before placing unit back
in operation.
2.1.2
Miswiring of furnace or improper
connections at limit switch(es).
ACTION 1 − Check for correct wiring and loose
connections. Correct wiring and/or replace any
loose connections.
2.2
− Unit operates with a cooling and con-
tinuous fan demand.
− Combustion air inducer will not start
with a Heating demand.
− Diagnostic lights flash the pressure
switch failure code.
LED#1−Off,
LED#2−Slow Flash
2.2.1
Miswiring of furnace or improper
connections to combustion air
inducer.
ACTION 1 − Check for correct wiring and loose
connections. Correct wiring and/or replace any
loose connections.
2.2.2
Prove switch stuck closed.
ACTION 1 − Check that the prove switch is open
without the combustion air inducer operating. Re-
place if defective.