Page 14 of 22
507635-05
Issue 2245
Heater Kit Accessory (if used)
The unit is fully equipped for operation without auxiliary
heat. A heater kit accessory may also be used. To install
the heater kit accessory (see Figure 5):
1. Disconnect the power and open the main control
access.
2. Disconnect the plug separating the high voltage wire
harness. Remove the high voltage wire harness plug
and discard.
3.
Remove the heater blockoff by removing the four
screws holding it in place.
4. Insert the heater into the control panel and fasten in
the same mounting holes.
5. Plug the heater wiring harness into the wire harness
on the control assembly. Field wiring of the auxiliary
heater is separate from the unit power supply. Wire the
power supply wiring for the heater to the appropriate
connections on the heater kit.
Sequence of Operation
Blower Control
Units are equipped with a variable speed motor that is
capable of maintaining a specified CFM throughout the
external static range. A particular CFM can be obtained by
positioning jumpers (COOL, HEAT, and ADJUST) on the
blower control. The HEAT and COOL jumpers are labeled
A, B, C and D. Each of the numbers corresponds with an
air volume (CFM) setting. The ADJUST jumper is labeled
Test, -, +, and Norm. The + and - pin settings are used to
add or subtract a percentage of the CFM selected. The
Test jumper is used to operate the motor in the test mode.
Figure 7 shows the blower control.
The CFM LED
located on the blower control flashes one
time per 100 cfm to indicate selected blower speed. For
example, if the unit is operating at 1200 CFM, the CFM
LED will flash 12 times. If the CFM is 1150, the CFM
LED will flash 11 full times plus one fast or half flash. At
times, the light may appear to flicker or glow. This takes
place when the control is communicating with the motor
between cycles. This is normal operation. Read through
the jumper settings section before adjusting the jumper to
obtain the appropriate blower speed. To change jumper
positions, gently pull the jumper off the pins and place it
on the desired set of pins. The following section outlines
the different jumper selections available and conditions
associated with each one. Refer to Figure 7.
From the engineering handbook and/or specification
sheet, determine which row most closely matches the
desired CFM. Once a specific row has been chosen (+,
NORMAL, or -), CFM volumes from other rows cannot be
used. Below are descriptions of the jumper selections.
The variable speed motor slowly ramps up to and down
from the selected air flow during both cooling and heating
demand. This minimizes noise and eliminates the initial
blast of air when the blower is initially energized.
ADJUST
The ADJUST pins allow the motor to run at normal speed,
approximately 10 percent higher, or approximately 10
percent lower than normal speed.
The TEST pin is available to bypass the blower control
and run the motor at approximately 70 percent to make
sure that the motor is operational. This is used mainly in
troubleshooting. The G terminal must be energized for the
motor to run.
COOL
The COOL jumper is used to determine the CFM during
cooling operation. In AC units, this jumper selection is
activated for cooling when Y1/Y2 is energized. In heat
pump units, the selection is activated for cooling when Y1/
Y2 and O are energized.
The blower motor runs at 80 percent of the selected air
flow for the first 7-1/2 minutes of each cooling demand.
This feature allows for greater humidity removal and saves
energy.
Figure 7.
