Troubleshooting Chart - Intertek MES80 Installation Instructions Manual

Troubleshooting Chart

Furnace Status LED Code¹ Fault Description(s)
• Furnace fails to
operate.
• Control LED · None
is off.
• Furnace fails to
operate.
• Control LED is
flashing ONE (1)
RED flash.
☼
1 Flash RED
• Furnace Fails to
☼
operate
• Control LED is 2 Flashes
flashing TWO (2) RED
RED flashes.
• Induced draft
blower runs
continuously with
no further furnace
☼
operation.
3 Flashes
• Control LED is
RED
flashing THREE
(3) RED flashes.
• Circulator
blower runs
continuously. No
furnace operation.
• Control LED is ☼
flashing FOUR 4 Flashes
(4) RED flashes. RED
• Induced draft
blower and
circulator blower
runs continuously. ☼
No furnace 5 Flashes
operation. RED
• Control LED is
flashing FIVE (5)
RED flashes.
• No 120-volt power • Manual disconnect switch
to furnace or 24-volt OFF, door switch open, or
power to integrated 24-volt wires improperly
control module. connected or loose.
· Integrated control has • Bad integrated control
an internal fault. module.
• Furnace lockout due • Failure to establish flame
to an excessive number maybe due to no gas to
of ignition attempts. burner, bad igniter or igniter
(3 total retries)² alignment, improper orifices, or
coated/oxidized or improperly
connected or shorted flame
sensor.
• Loss of flame after
establishment maybe due to
interrupted gas supply, lazy
burner flames (improper gas
pressure or restriction in flue or
improper induced draft blower
performance).
• Improperly connected igniter
or bad igniter or ground
connection to unit or burner.
• Faulty integrated control.
• Pressure sensor • Faulty wiring to the pressure
indicates pressure sensor.
reading when it should
• Faulty pressure sensor.
be zero.
• Inducer not making • Pressure sensor hoses
pressure setting. blocked, pinched or connected
improperly. Bad wire
• Induced draft blower is connection.
operating properly.
• Blocked intake, flue or weak
induced draft blower.
• Primary limit circuit is • Insufficient conditioned air
open. over the heat exchanger.
Blocked filters, restrictive
ductwork, improper circulator
blower speed, or failed
circulator blower.
• Faulty primary limit switch.
• Loose or improperly
connected wiring.
• Flame sensed with no · Faulty integrated control
call for heat. module.
Possible Causes
• Assure 120- and 24-volt
power to furnace integrated
control module.
• Check for possible shorts
in 120- and 24-volt circuits.
Repair as necessary.
• Replace bad control module.
• Locate and correct gas
interruption.
• Replace bad gas valve or
gas orifice size.
• Check flame sense signal.
Clean sensor if coated and/or
oxidized.
• Replace induced draft
blower pressure sensor.
Inspect pressure sensor
hose. Repair, if necessary.
Inspect flue or condensate
for blockage, proper length,
elbows, and termination.
• Compare igniter resistance
to specification. Replace
igniter if necessary.
• Check and correct unit
ground wiring.
• Replace bad control module.
• Check and correct pressure
sensor wiring.
• Replace pressure sensor.
• Replace induced draft
blower pressure sensor and
hoses. Replace with proper
parts.
• Check wiring connections.
• Inspect intake and flue for
blockage, proper length,
elbows, and termination.
• Replace induced draft
blower.
• Check circulator blower
speed and performance.
Correct speed or replace
blower if necessary.
• Check filters and ductwork
for blockage. Clean filters or
remove obstruction.
• Check primary limit.
• Check position of heat
exchanger shield.
• Check wiring connections.
· Replace bad integrated
control module.
30
Corrective Action Cautions & Notes
• Turn power OFF
prior to repair.
• Read precautions
in "Electrostatic
Discharge" section of
manual.
• Turn power and gas
OFF prior to repair.
· Igniter is fragile,
handle with care.
• Clean flame sensor
with steel wool.
• Replace igniter with
proper replacement
part.
• Read precautions
in "Electrostatic
Discharge" section of
manual.
• Turn power OFF
prior to repair.
• Replace pressure
sensor with proper
replacement part.
• Turn power OFF
prior to repair.
• See "Combustion
and Ventilation Air
Requirements" and
"Category I Venting
(Vertical Venting)"
section for details.
· Turn power OFF
prior to repair.
· Replace blower with
correct replacement
part.
· Replace primary
switch with proper
replacement part.
· Turn power OFF
prior to repair.