PROBLEM 1: UNIT FAILS TO OPERATE IN THE COOLING, HEATING, OR CONTINUOUS FAN MODE

Condition

Possible Cause

Corrective Action / Comments

 

 

 

1.5

1.5.1

ACTION 1 − Check that the unit is properly

− Diagnostic lights flash the improper

ground.

Improper ground to the unit.

ACTION 2 − Install a proper main ground to the

main ground.

unit

 

 

 

 

 

1.5.2

ACTION 1 − Check 6−pin connector for proper

 

 

LED#1−Alternating Fast Flash

6−Pin connector is improperly

installation. Correctly insert connector into con-

attached to the circuit board.

trol.

LED#2−Alternating Fast Flash

 

 

 

 

1.5.3

ACTION 1 − Check that the line voltage is above

 

Line voltage is below 75V.

75V. Determine cause of voltage drop and supply

 

correct voltage to the control.

 

 

 

 

1.5.4

ACTION 1 − Check for correct wiring and loose

 

Open ignitor circuit.

connections in the ignitor circuit. Check mult−plug

 

connections for correct installation.

 

 

 

 

1.5.5

ACTION 1 − Unplug ignitor and read resistance

 

Broken or failed ignitor.

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

 

 

ACTION 1 − Check continuity across switch(es).

− Unit operates with a cooling or contin-

 

 

 

2.1.1

Switches reset automatically upon cool down.

uous fan demand.

Primary, secondary or backup secon-

ACTION 2 − Check for restrictions on blower inlet

− Combustion air inducer will not start

air (including filter) and outlet air. Determine

dary

(if equipped ) limit open.

cause for limit activation before placing unit back

with a Heating demand.

 

 

in operation.

 

 

 

Diagnostic lights flash the limit failure mode.

 

2.1.2

ACTION 1 − Check for correct wiring and loose

 

 

LED#1−Slow Flash,

Miswiring of furnace or improper

connections. Correct wiring and/or replace any

connections at limit switch(es).

loose connections.

LED#2−On

 

 

 

 

 

 

2.2

 

 

− Unit operates with a cooling and con-

2.2.1

 

 

ACTION 1 − Check for correct wiring and loose

tinuous fan demand.

Miswiring of furnace or improper

connections. Correct wiring and/or replace any

− Combustion air inducer will not start

connections to combustion air

loose connections.

with a Heating demand.

inducer.

 

− Diagnostic lights flash the pressure

 

 

switch failure code.

 

 

2.2.2

ACTION 1 − Check that the prove switch is open

 

LED#1−Off,

Prove switch stuck closed.

without the combustion air inducer operating. Re-

place if defective.

LED#2−Slow Flash

 

 

Page 49

Page 49
Image 49
Lennox International Inc G61MP Improper ground to the unit, Main ground, LED#1−Alternating Fast Flash, LED#2−On

G61MP specifications

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