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and not switched by the control board. Motor operation is
also dependent on a pulsing D.C. signal on one of the four
speed taps on the motor. The airflow tables for heating and
cooling speeds show the relationship between airflow (CFM)
and external static pressure for each size furnace.
T
O AVOID PERSONAL INJURY OR DEATH DUE TO ELECTRICAL SHOCK
OFF
TURN
POWER TO THE FURNACE BEFORE CHANGING SPEED TAPS
Circulator Blower Speed Facts
1. Motor speed Tap wiring must remain in factory position
on the control board and motor.
2. There are 4 speed Tap wires to the motor T1, T2, T3,
T4.
3. There are 5 speeds available, depending on DIP switch
settings and found in air flow table for each size
furnace.
4. Heating input (W1/ W2) always has priority over all
other thermostat input.
5. Cooling input (YLo/ Y) has priority over continuous
fan input.
6. Continuous fan input (G) has lowest priority.
1. Refer to the air flow table for your specific model
furnace
2. If a cooling or heat pump condensing unit is being
used in conjunction with this furnace, DIP switches
S1-1, S1-2, S1-3 are used to select the proper
cooling speeds to match the outdoor unit size.
Typical CFM requirements are 400 CFM / Ton.
3. Heating speeds are selected DIP switches
S1-4 & S2-1
1. Turn OFF power to the furnace.
2. Select the cooling blower speeds that match the installa-
tion requirements from the airflow table in this manual
or the Service Manual, If factory cooling speeds do not
match the installation requirements, the dip switch set-
tings must be changed from factory position
3. Turn ON power to furnace.
4. Verify proper temperature rise in heat mode and CFM in
cooling mode
B
H
O
D
LOWER
EAT
FF
ELAY
The integrated control module provides a selectable heat off
delay function. The heat off delay period may be set to 90, 120,
150, 180 seconds using the DIP switches provided on the control
module. The delay is factory shipped at 150 seconds but may be
changed to suit the installation requirements and/or homeowner
preference. Refer to the following figures for switch positions
and corresponding delay times.
WARNING
T
IMINGS
PCBBF139 CONTROL BOARD
Purpose
Switch Group
Heating Fan Off
Delay
* FACTORY
,
SETTING
.
PCBBF137 CONTROL BOARD
Purpose
Switch Group
Heating Fan Off
S1
Delay
N
S
ORMAL
EQUENCE OF
P
U
OWER
P
•
When power is supplied, the control will energize
the Red LED, microcomputer runs its self-check
routine.
•
The control will check the status of the gas valve
circuitry.
•
Line polarity is checked.
•
The control then enters standby waiting for a call
for heat or cool.
•
The Furnace status LED will display a slow green
flash signaling standby mode.
H
M
EATING
ODE
Call for 1st Stage Heat Only:
•
On a call for first stage heat, the thermostat
contacts close signaling the control module.
•
The microcomputer runs its self-check routine.
•
The Amber LED will display a slow flash signaling
normal heat operation.
•
The control module checks the high limit (and/or
auxiliary limit) switch(es) for normally closed
contacts.
•
The control checks the low pressure switch for a
shorted condition
•
The gas valve relay status is checked for proper
operation. Once the low pressure switch is detected
open, the inducer blower is energized at high speed
and the humidifier is enabled.
•
The low pressure switch is checked for closure.
•
Once the low pressure switch is closed, the pre-
purge period begins. The inducer will be energized
at high speed for the pre-purge period.
49
Dip Switch
Function
1
2
90
120
S3
150
180
Function
1
90
120
150
180
O
PERATION
3
4
OFF
OFF
OFF
ON
ON*
OFF*
ON
ON
Dip Switch
2
3
4
OFF
OFF
ON
OFF
OFF
ON
ON
ON
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Table of Contents
Troubleshooting
