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SEQUENCE OF OPERATION
This appliance communicates with room thermostat through the low voltage connections described in "Thermostat location
and low voltage connections" section of this manual. It is the obligation of the installer to instruct the user how to use the
room thermostat and what the normal sequence of operation is in both the heating and cooling modes. It is important that
any troubleshooting and or repair to this appliance be performed by a qualified technician,
not by a user.
HEATING MODE
1.) The room thermostat demands heat.
2.) The furnace control checks for an open limit. If an open limit (main limit and auxiliary limit) is detected the appliance
will remain inoperable until the limit closes.
During an open limit condition the main circulating air blower will be energized.
The status indicator light on the furnace control will blink 4 times.
3.) The furnace control checks to ensure the vent pressure switch is open. If the vent pressure switch is closed the furnace
control will blink 2 times and not permit the furnace to be operational until this condition is remedied.
4.) The vent blower is energized.
5.) The vent pressure switch will close when it detects a pressure in excess of its setting. If the pressure switch should
fail to close the status light on the furnace control will flash 3 times. Until the vent pressure switch closes the ignition
sequence cannot begin.
6.) The flame rollout switches are checked to ensure that they are in the closed position.
7.) After a venter pre-purge of about 15 seconds the appliance hot surface ignitor will be energized.
8.) After a 17 second "ignitor warm-up" period the main valve will open.
9.) The burners will light and the flame sensor will detect the presence of burner flame. The ignitor will de-energize about
7 to 9 seconds. If the flame sensor does not detect the presence of main burner flame, the gas valve will close and steps
6 through 9 will be repeated for a maximum of 3 attempts. If after 3 attempts the flame sensor remains "open" the furnace
will go into a lock-out condition. The furnace will remain in a lock-out condition for 1 hour unless the room thermostat is reset.
10.) 30 seconds after the main valve is energized the heating speed of the circulating air blower is activated.
11.) The furnace will remain in operation until the room thermostat is satisfied.
12.) The gas valve will then be closed.
13.) The vent blower will turn off.
14.) The circulating air blower will turn off after approximately 2 1/2 minutes.
The furnace will remain dormant until the next demand for heat is received by the room thermostat. If an abnormality is
observed during the steps outlined above use the trouble-shooting guide enclosed with this furnace to assist in diagnosing
the problem.
COOLING MODE
1.) A demand for cooling is received by the room thermostat.
2.) The furnace control checks for an open limit. If an open limit (main limit and auxiliary limit) is detected the appliance
will remain inoperable until the limit closes.
During an open limit condition the main circulating air blower will be energized.
The status indicator light on the furnace control will blink 4 times.
3.) The condenser contactor will close.
4.) After about 7 seconds the circulating air blower will start on cooling speed.
5.) The furnace will remain in operation until the room thermostat is satisfied.
6.) The condenser contactor will then open.
7.) The circulating air blower will turn off after 60 seconds.
The furnace will remain dormant until the demand for cooling is received by the room thermostat. If an abnormality is observed
during the steps outlined above use the trouble-shooting guide enclosed with this furnace to assist in diagnosing the problem.
Summary of Contents for GMN SERIES
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