49
c. 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 instal
-
lation 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
Blower Heat Off Delay Timings
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 require
-
ments and/or homeowner preference. Refer to the following
figures for switch positions and corresponding delay times.
PCBBF139 CONTROL BOARD
1
2
3
4
90
OFF OFF
120
OFF ON
150
ON OFF
180
ON ON
*Factory Setting
S3
PURPOSE
Heating Fan
Off Delay
DIP SWITCH
SWITCH
GROUP FUNCTION
Normal Sequence of Operation
Power Up
•
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.
Heating Mode
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.
•
Following the completion of pre-purge, the inducer
switches to low speed and the igniter warm up period
begins.
•
After completion of the igniter warm up period:
a. Trial for ignition begins.
b. The first stage of the gas valve is energized.
•
The igniter is de-energized when flame is sensed
or at the conclusion of the ignition activation period
(IAP), whichever comes first.
•
When flame is sensed, the delay to heat on period
begins timing.
•
After the delay to heat on period, the circulator fan
is energized at the low heat speed.
•
The EAC contact is energized with the circulator.
Call for 2nd Stage After First Stage:
•
The inducer motor goes to high speed.
•
The pressure switches are checked for closure.
Closure of the second stage pressure switch will
energize the high fire stage of the gas valve.
•
The high speed circulator output is energized.
NOTE: A call for 2
nd
stage without a call for 1st
stage
will be ignored, and a three amber flash code will be
displayed on the LED. This error code will only be
stored in memory once during a single power cycle.
2nd Stage Satisfied, First Stage Still Calling:
•
When the second stage of the thermostat is satisfied,
the inducer blower is reduced to low speed which
de-energizes the second stage of the gas valve.
•
After the high heat off delay expires, the circulator
is reduced to low heat speed.
•
Note: A call for second stage without a call for first
stage will be ignored.
Cooling Mode
Low stage cooling Mode sequence:
•
On a call for lo cool, the YLO and G thermostat
contacts close signaling the control module.
•
The LED will display a “GREEN”1 flash
•
The compressor and condenser fan are energized.
The compressor is connected to the YLO terminal
of the control module.
•
The circulator fan is energized at lo cool speed after
a cool on delay. The electronic air cleaner will also
be energized.
