Nordyne G6RL 90+, G6RC 90+, G6RD 93+ Sequence of Operation, Heating Mode, Cooling Mode

•Change or replace the air filters monthly during any period when the circulating blower is operating regularly.

•Always replace the doors on the furnace after servicing. Do not operate the furnace without all doors and covers in place.

•Avoid operating the furnace when win- dows and doors are open.

•Be sure that the thermostat is properly installed and is not being affected by drafts or heat from lamps or other appliances.

Sequence of Operation

Operating sequences for the heating, cooling, and fan modes are described below. Refer to the wiring diagrams (Figures 26 and 27) and the low voltage field wiring diagram (Figure 24).

Heating Mode:

1.On a call for heat the thermostat closes, applying 24 VAC to the W terminal on the control board.

2.The control board checks for continuity on the 24 VAC limit control circuit (over-tem- perature limit switch, flame rollout switches and blocked vent switch in series). If an open limit is detected the control board will energize the inducer and the conditioned air blower. All other system functions will be inoperable until the limit circuit closes. While the limit is open, the red LED will pulse at a rate of 1 blink per unit time.

3.The furnace control checks for continuity across the pressure switch (24 VAC). If the pressure switch is closed the heat mode sequence will not continue. If it remains closed for 10 seconds the red LED will blink 3 times repetitively until the fault condition clears.

4.The inducer is energized.

5.The pressure switch will close. If the pres- sure switch does not close after 10 seconds the fault LED will blink 2 times repetitively and the inducer will continue to run until the switch is closed.

6.The inducer will pre-purge for 30 seconds and then the ignitor will start its warm-up. After 30 seconds of ignitor warm-up the gas valve (24 VAC) will open. The ignitor circuit stays energized for 6 seconds after the gas valve opens.

7.The furnace control must prove flame via the flame sensor six seconds after the gas valve opens. If flame is sensed, all burners are on and the ignitor cools off. If no flame is sensed, the gas valve closes immediately and the inducer continues to run. A second trial for ignition (step 6) begins if no flame is sensed. On the fifth try for ignition, the furnace control is locked out and the red LED will blink 4 times repetitively. The ther- mostat must be opened for at least ten seconds to reset the furnace control after a lock out. Otherwise, the furnace will attempt another ignition sequence in 1 hour.

8.The furnace control energizes the circulat- ing air blower on the heating speed 30 seconds after the gas valve circuit is ener- gized .

9.When the thermostat has been satisfied, gas valve is de-energized.

10.The inducer is de-energized after a 30 second postpurge.

11.The furnace control keeps the circulating air blower energized for 120 seconds (factory set) or 60, 90, or 180 seconds (field adjust- able). (See Figure 25.)

12.Abnormal conditions: If a limit opens during operation, the inducer and circulating air blower continue to operate. The gas valve is de-energized immediately. The blowers continue to operate until the limit closes. When the limit closes the inducer blower is de-energized immediately. The circulating air blower continues to operate for the speci- fied delay (factory set at 120 seconds).

Cooling Mode:

1.On a call for cooling the thermostat closes, applying 24 VAC to the G and Y terminals on the furnace control. This closes the compressor contactor.

2.The furnace control energizes the circulat- ing blower (115 VAC) on the cooling speed.

3.When the thermostat is satisfied, the G and Y terminals on the control board are de-energized opening the compressor con- tactor.

4.The circulating air blower is de-energized after a 90 second delay.

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