Nordyne M3RL System Operation Information, Lubrication, Condensate Drain Assembly, General

!WARNING:

Never operate the furnace without a filter in place. Dust and lint in the return air can build up on internal compo- nents, resulting in loss of efficiency, equipment damage, and possible fire.

Lubrication

The bearings in the circulating air blower mo- tors are pre-lubricated and sealed at the fac- tory. No further oiling of the bearings is required for the life of the motor.

Condensate Drain Assembly

Be sure the condensate lines are free and open (i.e. avoid kinking hoses). Also make sure all hose clamps are tight to avoid drawing air into the system.

Blower Compartment

The blower compartment should be cleaned monthly during the heating and cooling sea- sons to remove any dirt and lint that may have accumulated in the compartment or on the blower and motor. Dirt and lint can create excessive loads on the motor resulting in higher than normal operating temperatures and short- ened service life.

Heat Exchanger and Burner Maintenance The furnace should operate for many years without excessive soot buildup in the flue pas- sageways, however, the flue passageways, the vent system, and the burners should be inspected and cleaned (if required) by a quali- fied service technician annually to ensure con- tinued safe operation. Particular attention must be given to identify deterioration from corrosion or other sources.

SYSTEM OPERATION

INFORMATION

GENERAL

Proper maintenance is most important to achieve the best performance from a furnace. Follow these instructions for years of safe, trouble free operation.

•Do not place combustible materials on or against the furnace cabinet or the vent pipe.

•Do not store gasoline or any other flammable vapors and liquids in the vicinity of the furnace.

•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 windows 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 30) and the low voltage field wiring diagram (Figure 26) for more details.

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- temperature limit switch, flame rollout switches and blocked vent switch in se- ries). If an open limit is detected the con- trol board will energize the inducer and the conditioned air blower. All other sys- tem 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 pressure 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 igniter will start its warm-up as follows:

30