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CONTROL MODULE STATUS INDICATORS - MG1 SERIES
RED LED
INDICATOR
STATUS
Steady ON
Control OK
Steady OFF
No power
Rapid flash
False flame or internal control fault
One flash
Limit switch is open
Two flashes
Pressure switch is open
Three flashes
Pressure switch is stuck closed
Four flashes
Lockout due to failed ignition
Five flashes
L1 neutral reversed or L1 voltage not present
on L1
Flame Status - A Yellow LED labeled “Flame” is provided to indicate
flame status. When flame is sensed, the flame LED is lit. If flame sense
is weak, yellow LED will flash.
Table 7. Nordyne/UTEC Control Board
Fault Conditions
OPERATING SEQUENCE
Direct Ignition Furnaces
1. On a call for heat, the thermostat contacts close,
supplying 24 VAC between terminals
C
and
W
of the
control module.
2. When the inducer starts, the air pressure switch closes.
differential pressure and energizes the gas valve.
3. After a 45 second purge, the control energizes the Hot
Surface Ignitor (HSI) output for the appropriate warm-up
time. After warm up, the gas valve opens.
NOTE:
The
time for ignition is approximately 6 seconds, after which
the gas valve either remains open if flame is sensed,
or closes if flame is not sensed.
4. If flame is not sensed, the sequence repeats four more
times before a lockout occurs. To reset, wait 30 seconds
and then interrupt the 24 VAC power by turning the room
thermostat below room temperature, then returning it
to the original set point.
5. If flame does not establish on the 5th attempt (initial
fire + 4 re-tries), the control de-energizes the gas valve,
the
red
LED flashes 4 times, and the furnace locks out
heat operation for 1 hour. See
6. If a flame is present, the control energizes the main
blower on heat speed 30 - 45 seconds after the gas
valve opens.
WARNING:
Should overheating occur or the gas supply fails
to shut off, shut off the manual gas valve to the
furnace before shutting off the electrical supply.
7. When call for heat is satisfied the thermostat contacts
open, the gas valve shuts off gas flow and the combustion
blower remains on for a 30 - 45 second post-purge
period.
8. The main blower is de-energized after a 120 - 150
second blower off delay.
TROUBLESHOOTING
High Gas Bills
a. Verify the proper orifice is being used. See
b. Check the return air system. Is it clear and free of
blockage?
c. Check the furnace filter. Is it clean or need replacing?
d. Verify the home is insulated, windows and doors fit tightly,
and there are no leaks in the heating duct system.
e. Check the room thermostat. Is the setting higher than
necessary? Low humidity requires higher temperatures
for the same level of comfort. Check for proper humidity
level in the home.
Burner Motor won’t Run - T-stat Calls for Heat
1. Check the electrical supply to the furnace.
2. Verify the furnace On-Off switch is in the ON position.
or
3. Defective thermostat circuit - white and red thermostat
low voltage leads. If the combustion fan runs, check:
• Thermostat connections
• Thermostat
4. No voltage to control module - determine if 24 volts (or
120 volts) is available to the control module. If voltage
is not available check for:
• Blown fuse, defective transformer, circuit breaker, no
electrical supply.
• Limit switch open.
• Loose connections.
RED LED
FLASH
ERROR/CONDITION
1
System Lockout (Retries Exceeded)
2
Pressure Switch Stuck Closed
3
Pressure Switch Stuck Open
4
Open High Temperature Limit Switch
5
Flame Sensed > 4.25 Seconds with Gas Valve
De-Energized
6
Open Flame RO Switch
8
Igniter Relay Fault
10
Open Fuse
11
Igniter Open
12
Inducer Relay Error
Flash codes NOT stored in memory
7
Low Flame Sense Signal
9
Twinning Fault
Off
Control Failure / No Power / Internal Fault / IRQ Loss
Gas Heating Lockout (Gas valve energized when it
should be de-energized)
Or Gas Valve De-energized when it should be
Energized
Rapid Flash Reverse Polarity
Continuous
On
Normal Operation
Table 8. Emerson Control Board Fault Conditions
Содержание MG1 Series
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