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WARNING
!
ELECTRICAL SHOCK HAZARD
Failure to follow this warning could result in personal
injury or death.
Disconnect electrical power to the unit and install lockout
tag before changing blower speed.
The
standard
evaporator fan motor is factory set to provide 5
different fan speeds to choose from for the various operation
modes (see Table 4). All models are factory- -shipped for nominal
high stage and low stage cooling airflow operation at minimum
external static pressure. See Table 2.
Table 4 – Color Coding for Indoor Fan Motor Leads
Black = High Speed
Orange = Med--High Speed
Red = Med Speed
Pink = Med--Low Speed
Blue = Low Speed
Selection of Proper Fan Speeds for Operation Modes:
Low Stage Cooling/Heat Pump (All Models
Dehumidification): Using Tables 8 , 9, and 10, find the external
static pressure drops for wet coil, economizer, and filter, and add
them to dry coil measured on the system. Using this total static
pressure, look up Table 5 to find the airflows available at the total
static pressure. For 208/230 VAC models, connect the chosen fan
speed wire to "LO COOL" connection on the IFB Board (see Fig.
11). For 460 VAC models, connect the chosen fan speed wire to
"LOW" connection on the IFB (see Fig. 11).
High Stage Cooling/Heat Pump (All Models without Advanced
Dehumidification):Using Table 8 , 9, and 10, find the external
static pressure drops for wet coil, economizer, and filter, and add
them to dry coil measured on the system. Using this total static
pressure, look up Table 5 to find the airflows available at the total
static pressure. The speed chosen must provide airflow of between
350 to 450 CFM per ton of cooling. For 208/230 VAC models,
connect the chosen fan speed wire to "HI COOL" connection on
the IFB Board (See Fig. 11). For 460 VAC models, connect the
chosen fan speed wire to "HIGH" connection on the IFB (see Fig.
11).
High Stage Enhanced Dehumidification Cooling (208/230 VAC
Models without Advanced Dehumidification): Using the total
static pressure for selecting the high stage cooling speed, look up
Table 5 to find lower speed/airflows available at that total static
pressure. All airflows highlighted in Table 5 are acceptable for the
Dehum speed. The speed chosen must provide airflow of between
320 to 400 CFM per ton of cooling. To activate the high stage
enhanced dehumidification cooling mode, the shunt jumper must
be moved from the "No DH" to the "DH" selection. (See Fig. 11,
close up.) For 208/230 VAC models, connect the chosen fan speed
wire to "DHUM" connection on the IFB Board (see Fig. 11).
Continuous
Fan
(All
Dehumidification): Continuous fan speed is the same speed as
Low Stage Cooling.
To activate the high stage enhanced dehumidification cooling
mode, the shunt jumper in Fig. 11 must be moved from the No DH
to DH selection (See Fig. 11, close up).
Using the Same Fan Speed for More than One Mode: Some fan
speeds are ideal for more than one mode of operation. It is
permissible to use a field- -supplied jumper wire to connect one
speed tap wire to two or more speed connections on the Interface
Fan Board (IFB). Jumper wires must use 18 AWG wire with at
least 2/64" insulation.
Cooling/Heat
Pump/Continuous
Dehumidification: For Advanced Dehumidification models, to
without Advanced
Models
without
Advanced
Fan
with
Advanced
use the dehumidification feature, cut the J1 jumper found on the
Interface Fan Board (IFB). (See Fig. 11 and 16.) For proper
operation, the dehumidistat must open on humidity rise above the
humidity set point. The unit will naturally adapt airflow to the
external static pressure drop measured on the system. There is no
need to adjust the factory installed taps.
SEQUENCE OF OPERATION
a. Continuous Fan
(1.) Thermostat closes circuit R to G energizing the
blower motor for continuous fan. The indoor fan is
energized on low speed.
b. Cooling Mode
(1.) Low Stage: Thermostat closes R to G, R to Y1,
and R to O. The compressor and indoor fan are
energized on low speed. The outdoor fan is also
energized
(2.) High Stage: Thermostat closes R to G, R to Y1, R
to Y2, and R to O. The compressor and indoor fan
are energized on high speed. The outdoor fan is
also energized.
c. Electric Heating Mode
(1.) Thermostat closes circuit R to W2 or W3, and R to
G. There are no on or off delays.
d. Heat Pump Heating
(1.) Low Stage: Thermostat closes R to G, R to Y1.
The compressor and indoor fan are energized on
low speed. The outdoor fan is also energized
(2.) High Stage: Thermostat closes R to G, R to Y1, R
to Y2. The compressor and indoor fan are ener-
gized on high speed. The outdoor fan is also ener-
gized.
e. Heat Pump Heating with Auxiliary Heat
(1.) Thermostat closes circuits R to G, R to Y and R to
W/W1 or W2. The compressor, indoor and outdoor
fans are energized, as well as the electric heat
relays.
f. Defrost Mode
The defrost mode is automatically energized by the
defrost board during heating mode. The defrost board
energizes "O" (reversing valve) and "W2" (electric
heat). It also de- -energizes the outdoor fan. When defrost
is complete, unit will return to heating mode. If room
thermostat is satisfied during defrost, unit will shut
down and restart in defrost on next call for heat.
Step 4 — Defrost Control
Quiet Shift
Quiet Shift is a field- -selectable defrost mode, which will eliminate
occasional noise that could be heard at the start of defrost cycle and
restarting of heating cycle. It is selected by placing DIP switch 3
(on defrost board) in ON position.
When Quiet Shift switch is placed in ON position, and a defrost is
initiated, the following sequence of operation will occur. Reversing
valve will energize, outdoor fan will turn off, compressor will turn
off for 30 sec and then turn back on to complete defrost. At the
start of heating after conclusion of defrost reversing valve will
de- -energize, compressor will turn off for another 30 sec, and the
outdoor fan will stay off for 40 sec, before starting in the Heating
mode.
Defrost
The defrost control is a time/temperature control which includes a
field- -selectable time period (DIP switch 1 and 2 on the board)
between defrost cycles of 30, 60, 90, or 120 minutes (factory set at
60 minutes). To initiate a forced defrost, two options are available
depending on the status of the defrost thermostat.
13
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