!WARNING
ELECTRICAL SHOCK HAZARD
Failure to follow this warning could result in personal injury or death.
Before making any indoor wiring adjustments, shut off gas supply. Then disconnect electrical power to the unit and install lockout tag before changing blower speed.
This unit has independent fan speeds for gas heating and cooling. In addition, this unit has the
This unit is
10.There are 3 additional speed tap wires available for use in either gas heating or cooling (For color coding on the indoor fan motor leads, see Table 6). The additional 3 speed tap wires are shipped loose with vinyl caps and are located in the control box, near the interface fan board (IFB) (Fig. 14).
Gas Heating Fan Speed Set-up
To change the gas heating speed:
1.Remove the vinyl cap off of the desired speed tap wire (Refer to Table 6 for color coding). Table 10 shows the temperature rise associated with each fan speed for a given static pressure. Make sure that the speed chosen delivers a temperature rise within the rise range listed on the unit rating plate.
2.Remove the current speed tap wire from the “GAS HEAT” terminal on the interface fan board (IFB) (Fig.14) and place vinyl cap over the connector on the wire.
3.Connect the desired speed tap wire to the “GAS HEAT” terminal on the interface fan board (IFB).
Single Cooling Fan Speed
To change cooling speed:
1.Remove the vinyl cap off of the desired speed tap wire (Refer to Table 6 for color coding). Add the wet coil pressure drop in Table 8 to the system static to determine the correct cooling airflow speed in Table 10 that will deliver the nominal cooling airflow as listed in Table 1 for each size.
2.Remove the current speed tap wire from the “LOW” terminal on the interface fan board (IFB) (Fig. 14) and place vinyl cap over the connector on the wire.
3.Connect the desired speed tap wire to the “LOW” terminal on the interface fan board (IFB).
Two Cooling Fan Speeds Set-up (Dehumidification feature used)
IMPORTANT: Dehumidification control must open control circuit on humidity rise above set point.
Use of the dehumidification cooling fan speed requires use of either a 24 VAC dehumidistat or a thermostat which includes control of a 24 VAC dehumidistat connection. In either case, the dehumidification control must open the control circuit on humidity rise above the dehumidification set point. Dehumidification controls are available with the reverse logic; these must not be used.
1.Remove fan speed tap wire from the “LOW” terminal on the interface fan board (IFB) (Fig. 14).
2.Determine correct normal cooling fan speed for unit and application. Add the wet coil pressure drop in Table 8 to the system static to determine the correct cooling airflow speed in Table 10 that will deliver the nominal cooling airflow as listed in Table 1 for each size.
3.Remove the vinyl cap off of the desired speed tap wire (Refer to Table 6 for color coding) for the normal cooling fan speed and place desired speed tap wire on “HIGH” on the interface board.
4.Refer to airflow tables (Table 10) to determine allowable speeds for the dehumidification cooling fan speed. In Table 10, speeds that are not allowed for dehumidification cooling are shaded.
5.Remove the vinyl cap off of the desired speed tap wire (Refer to Table 6 for color coding) for the dehumidification cooling fan speed and place desired speed tap wire on the “LOW” connection on the interface board (IFB). Verify that static pressure is in the acceptable range for the speed tap to be used for dehumidification cooling.
6.Use any spare vinyl plugs to cap any unused speed tap wires.
NOTE: For heat pump operation, the recommended airflow is 350 to 450 CFM for each 12,000 Btuh of rated cooling capacity.
Continuous Fan Operation
When the DEHUM feature is not used, the continuous fan speed will be the same as cooling fan speed. When the DEHUM feature is used, the continuous fan will operate on IFB “LOW” speed when the DH control lead is not energized, or IFB “HIGH” speed when the DH lead is energized (see Fig. 14).
Table 6 – Color Coding for Indoor Fan Motor Leads
Black = High Speed
Orange =
Red = Med Speed
Pink =
Blue = Low Speed
677C-- -- A
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