Johnson Controls CM8M/CMLM*MP Supply Voltage Connections, LOW Voltage Control Wiring Connections

368261-UIM-A-0508

SUPPLY VOLTAGE CONNECTIONS

Junction Box

Connect ground lead to screw

Electrical Entry

L1-Hot BLK

Neutral WHT

FIGURE 19: Electrical Wiring

1.Provide a power supply separate from all other circuits. Install overcurrent protection and disconnect switch per local/national electrical codes. The switch should be close to the unit for conve- nience in servicing. With the disconnect or fused switch in the OFF position, check all wiring against the unit wiring label. Refer to the wiring diagram in this instruction.

2.Remove the screws retaining the wiring box cover. Route the power wiring through the opening in the unit into the junction box with a conduit connector or other proper connection. In the junc- tion box there will be 3 wires, a Black Wire, a White Wire. Connect the power supply as shown on the unit-wiring label on the inside of the blower compartment door or the wiring schematic in this sec- tion. The black furnace lead must be connected to the L1 (hot) wire from the power supply. The white furnace screw must be con- nected to neutral. Connect the power supply ground to the green screw (equipment ground) An alternate wiring method is to use a field provided 2” (5.1 cm) x 4” (10.2 cm) box and cover on the out- side of the furnace. Route the furnace leads into the box using a protective bushing where the wires pass through the furnace panel. After making the wiring connections replace the wiring box cover and screws. Refer to Figure 19, "Electrical Wiring".

3.The furnace's control system requires correct polarity of the power supply and a proper ground connection. Refer to Figure 19, "Elec- trical Wiring"

The power connection leads and wiring box may be relocated to the left side of the furnace. Remove the screws and cut wire tie holding excess wiring. Reposition on the left side of the furnace and fasten using holes provided.

LOW VOLTAGE CONTROL WIRING CONNECTIONS

Install the field-supplied thermostat by following the instructions that come with the thermostat. With the thermostat set in the OFF position and the main electrical source disconnected, connect the thermostat wiring from the wiring connections on the thermostat to the terminal board on the ignition module, as shown in Figures 20-25, Thermostat Charts. Electronic thermostats may require the common wire to be con- nected as shown in Figure 16, "Gas Valve". Apply strain relief to ther- mostat wires passing through cabinet.

Set the heat anticipator in the room thermostat to 0.4 amps. Setting it lower will cause short cycles. Setting it higher will cause the room temperature to exceed the set points.

Some electronic thermostats do not have adjustable heat anticipa- tors. They should be set to six cycles per hour. Follow the thermo- stat manufacturer's instructions.

The 24-volt, 40 VA transformer is sized for the furnace components only, and should not be connected to power auxiliary devices such as humidifiers, air cleaners, etc. The transformer may provide power for an air conditioning unit contactor.

AIR CONDITIONER CONNECTIONS

This furnace may be used with single-stage or two-stage air condition- ing units.

For Single-Stage A/C - Connect the low voltage wiring as shown in Figures 20, Thermostat Chart.

For Two-Stage A/C - Use a two-stage thermostat, connect the low volt- age wiring as shown in Figures 21, Thermostat Chart.

For Two-Stage A/C using a Single-Stage Thermostat - connect the low voltage wiring as shown in Figures 21, Thermostat Chart.

This furnace control board can control a two-stage A/C using only a sin- gle-stage thermostat. In this case, the furnace control switches between high cool and low cool based on the calculated cooling load.

ZONING OPERATION

This furnace may be used in zoning systems, using a separate after- market zoning control. For use in zoned systems, put the ZONE CON- TROL jumper on the furnace control board in the “YES” position.

HEAT PUMP OPERATION

This furnace may be used in conjunction with a heat pump in dual fuel applications. For heat pump applications, put the HEAT PUMP jumper on the furnace control board in the “YES” position. Connect the low volt- age wiring as shown in Figures 20-25, Thermostat Charts. If a two- stage heat pump is to be used, a two-stage thermostat is required.

Johnson Controls Unitary Products 11