Bryant 312AAV L Series Installation and user guide

NOTE: Read the entire instruction manual before starting the
installation.
These procedures are for size 90,000 Btuh input unit.
TABLE OF CONTENTS
SAFETY CONSIDERATIONS .....................................................1
INTRODUCTION..........................................................................1
General ......................................................................................1
ELECTROSTATIC DISCHARGE (ESD) PRECAUTIONS
PROCEDURE ................................................................................2
CARE AND MAINTENANCE.....................................................2
Cleaning And/Or Replacing Air Filter.....................................2
Blower Motor and Wheel.........................................................3
Cleaning Heat Exchanger .........................................................4
Electrical Controls and Wiring.................................................5
WIRING DIAGRAMS...................................................................8
TROUBLESHOOTING .................................................................8
SAFETY CONSIDERATIONS
Installing and servicing heating equipment can be hazardous due to
gas and electrical components. Only trained and qualified
personnel should install, repair, or service heating equipment.
Untrained personnel can perform basic maintenance functions
such as cleaning and replacing air filters. Observe precautions in
the literature, on tags, and labels attached to or shipped with the
unit and other safety precautions that may apply.
Follow all safety codes. In the United States, follow all safety
codes including the National Fuel Gas Code (NFGC) NFPA
54-1999/ANSI Z223.1-1999. In Canada, refer to the CAN/CGA-
B149.1- and .2-M95 National Standard of Canada, Natural Gas
and Propane Installation Codes (NSCNGPIC). Wear safety glasses
and work gloves. Have fire extinguisher available during start-up
and adjustment procedures and service calls.
This is the safety-alert symbol . When you see this symbol on
the furnace and in instructions or manuals, be alert to the potential
for personal injury.
Understand the signal words DANGER, WARNING, CAUTION,
and NOTE. These words are used with the safety-alert symbol.
DANGER identifies the most serious hazards which will result in
severe personal injury or death. WARNING signifies a hazard
which could result in personal injury or death. CAUTION is used
to identify unsafe practices which would result in minor personal
injury or product and property damage. NOTE is used to highlight
suggestions which will result in enhanced installation, reliability,
or operation.
WARNING: The ability to properly perform mainte-
nance on this equipment requires certain knowledge,
mechanical skills, tools, and equipment. If you do not
possess these, do not attempt to perform any maintenance
on this equipment other than those procedures recom-
mended in the User’s Manual. FAILURE TO FOLLOW
THIS WARNING COULD RESULT IN POSSIBLE
DAMAGE TO THIS EQUIPMENT, SERIOUS PER-
SONAL INJURY, OR DEATH.
CAUTION: Label all wires prior to disconnection when
servicing controls. Wiring errors can cause improper and
dangerous operation.
INTRODUCTION
I. GENERAL
These instructions are written as if the furnace is installed in an
upflow application. An upflow furnace application is where the
blower is located below the combustion and controls section of the
furnace, and conditioned air is discharged upward. Since this
furnace can be installed in any of the 4 positions shown in Fig. 2,
you must revise your orientation to component location accord-
ingly.
CERTIFIED ®
REGISTERED QUALITY SYSTEM Fig. 1—Model 312AAV Multipoise
A00353
service and
maintenance procedures
GAS-FIRED
INDUCED-COMBUSTION FURNACE
Cancels: New SP04-68
11-00
312AAV
Series L
—1—

ELECTROSTATIC DISCHARGE (ESD) PRECAUTIONS
PROCEDURE
CAUTION: Electrostatic discharge can affect electronic
components. Take precautions during furnace installation
and servicing to protect the furnace electronic control.
Precautions will prevent electrostatic discharges from
personnel and hand tools which are held during the
procedure. These precautions will help to avoid exposing
the control to electrostatic discharge by putting the
furnace, the control, and the person at the same electro-
static potential.
1. Disconnect all power to the furnace. DO NOT TOUCH
THE CONTROL OR ANY WIRE CONNECTED TO THE
CONTROL PRIOR TO DISCHARGING YOUR BODY’S
ELECTROSTATIC CHARGE TO GROUND.
2. Firmly touch a clean, unpainted, metal surface of the
furnace chassis which is close to the control. Tools held in
a person’s hand during grounding will be satisfactorily
discharged.
3. After touching the chassis you may proceed to service the
control or connecting wires as long as you do nothing that
recharges your body with static electricity (for example; DO
NOT move or shuffle your feet, DO NOT touch un-
grounded objects, etc.).
4. If you touch ungrounded objects (recharge your body with
static electricity), firmly touch furnace again before touch-
ing control or wires.
5. Use this procedure for installed and uninstalled (un-
grounded) furnaces.
6. Before removing a new control from its container, dis-
charge your body’s electrostatic charge to ground to protect
the control from damage. If the control is to be installed in
a furnace, follow items 1 through 5 before bringing the
control or yourself into contact with the furnace. Put all
used AND new controls into containers before touching
ungrounded objects.
7. An ESD service kit (available from commercial sources)
may also be used to prevent ESD damage.
CARE AND MAINTENANCE
For continuing high performance and to minimize possible equip-
ment failure, periodic maintenance must be performed on this
equipment. Consult your local dealer about proper frequency of
maintenance and the availability of a maintenance contract.
WARNING: Never store anything on, near, or in contact
with the furnace, such as:
1. Spray or aerosol cans, rags, brooms, dust mops,
vacuum cleaners, or other cleaning tools.
2. Soap powders, bleaches, waxes or other cleaning
compounds, plastic or plastic containers, gasoline,
kerosene, cigarette lighter fluid, dry cleaning fluids, or
other volatile fluids.
3. Paint thinners and other painting compounds, paper
bags, or other paper products.
A failure to follow this warning could result in
corrosion of the heat exchanger, fire, personal injury,
or death.
WARNING: Turn off the gas and electrical supplies to
the unit before performing any maintenance or service.
Follow the operating instructions on the label attached to
the furnace. A failure to follow this warning could result
in personal injury.
The minimum maintenance on this equipment is as follows:
1. Check and clean air filter each month or more frequently if
required. Replace if torn.
2. Check blower motor and wheel for cleanliness each heating
and cooling season. Clean as necessary.
3. Check electrical connections for tightness and controls for
proper operation each heating season. Service as necessary.
CAUTION: Personal injury can result from sharp metal
edges, etc. Be careful when removing parts.
I. CLEANING AND/OR REPLACING AIR FILTER
The air filter arrangement may vary depending on the application.
NOTE: If the filter has an airflow direction arrow, the arrow must
point towards the blower.
WARNING: Never operate unit without a filter or with
filter access door removed. A failure to follow this
warning could result in fire, personal injury, or death.
To clean or replace filter, proceed as follows:
-Filters installed in media cabinet adjacent to furnace (See Fig. 3):
a. Turn off electrical supply to furnace before removing
filter access door.
b. Remove filter cabinet door.
c. Slide filter out of cabinet.
d. If equipped with permanent, washable filter, clean filter
by spraying cold tap water through filter in opposite
direction of airflow. Rinse filter and let dry. Oiling or
coating of the filter is not recommended.
e. If equipped with factory-specified disposable media
filter, replace only with media filter having the same part
number and size.
Fig. 2—Multipoise Orientation
A93041
UPFLOW
DOWNFLOW
HORIZONTAL
LEFT
AIRFLOW AIRFLOW
AIRFLOW
AIRFLOW
HORIZONTAL
RIGHT
TABLE 1—FILTER SIZE INFORMATION (IN.)
FURNACE
CASING WIDTH
FILTER QUANTITY AND SIZE FILTER
TYPE
Side Return Bottom Return
17-1/2 (1) 16 X 25 X 1* (1) 16 X 25 X 1* Cleanable
*
Factory-provided with the furnace.
—2—

f. Slide filter into cabinet.
g. Replace filter cabinet door.
h. Turn on electrical supply to furnace.
II. BLOWER MOTOR AND WHEEL
The following steps should be performed by a qualified service
technician.
To ensure long life and high efficiency, clean accumulated dirt and
grease from blower wheel and motor annually.
The inducer and blower motors are pre-lubricated and require no
additional lubrication. These motors can be identified by the
absence of oil ports on each end of the motor.
Clean blower motor and wheel as follows:
1. Turn off electrical supply to furnace.
2. Remove 2 screws from outer door and then remove outer
door.
3. Vent pipe through furnace casing installation only. For
downflow or horizontal furnaces having vent pipes within
the furnace that pass in from of the blower door:
a. Disconnect vent connector from furnace vent elbow.
b. Disconnect and remove short piece of vent pipe from
within furnace.
4. Remove 2 screws from blower door and remove blower
door.
5. Disconnect blower leads from furnace control. Notice wire
color and location for reassembly.
All other factory wires can be left connected, but field
thermostat connections may need to be disconnected de-
pending on their length and routing.
6. Remove 2 screws securing control and transformer support
to furnace panel.
7. Hang control and transformer support to front of furnace
casing and away from blower compartment.
8. Remove 2 screws holding blower assembly to blower deck
and slide blower assembly out of furnace.
9. Clean blower wheel and motor using a vacuum with soft
brush attachment. Do not remove or disturb balance weights
(clips) on blower wheel blades. The blower wheel should
not be dropped or bent as balance will be affected.
10. If a greasy residue is present on blower wheel, remove
wheel from the blower housing and wash it with an
appropriate degreaser. To remove wheel:
a. Mark blower wheel location on shaft before disassembly
to ensure proper reassembly.
b. Loosen setscrew holding blower wheel on motor shaft.
NOTE: Mark blower mounting arms, motor, and blower housing
so motor and each arm is positioned at the same location during
reassembly.
c. Mark blower wheel orientation and cutoff plate location
to ensure proper reassembly.
d. Remove screws securing cutoff plate and remove cutoff
plate from housing.
e. Disconnect capacitor and ground wire attached to blower
housing before removing motor.
f. Remove bolts holding motor and motor mounts to blower
housing and slide motor and mounts out of housing.
Motor mount belly band need not be removed unless
motor is to be replaced.
Fig. 3—Model 312AAV Upflow
A00342
OUTER DOOR
MOUNTING SCREWS
VENT ELBOW
RATING PLATE
DRAFT
SAFEGUARD SWITCH
GAS MANIFOLD
GAS BURNER
FLAME SENSOR
BLOWER DOOR
SAFETY SWITCH
BLOWER, MOTOR
AND CAPACITOR
PRESSURE
SWITCH
FLUE
COLLECTOR
BOX
GAS VALVE
MANUAL RESET
LIMIT SWITCHES
HOT SURFACE
IGNITER
CONTROL
MAIN LIMIT SWITCH
—3—

g. Remove blower wheel from housing.
CAUTION: The blower wheel should not be dropped or
bent as balance will be affected.
11. Reassemble motor and blower by reversing items 9a
through 9g. Be sure to reattach ground wire.
12. Reinstall blower assembly in furnace.
13. Reinstall control and transformer support assembly in
furnace.
14. Reconnect blower leads to furnace control.
Refer to furnace wiring diagram, and connect thermostat
leads if previously disconnected. (See Fig. 7.)
NOTE: Refer to Table 2 for motor speed lead relocation if leads
were not identified before disconnection.
CAUTION: Heating air speed selection MUST be ad-
justed to provide proper air temperature rise as specified
on the rating plate. Failure to adjust the heating speed
may shorten heat exchanger life. Recommended opera-
tion is at the midpoint of rise range or above.
15. Downflow or horizontal furnaces with vent pipe through
furnace only: Reinstall internal vent pipe by reversing items
3a and 3b.
16. Reinstall vent connector to furnace vent elbow. Securely
fasten vent connector to vent elbow with 2 field-supplied,
corrosion-resistant, sheet metal screws located 180° apart.
17. Turn on electrical supply. Manually close blower access
door switch. Use a piece of tape to hold switch closed.
Check for proper rotation and speed changes between
heating and cooling by jumpering R-to-W/W1 R-to-W/W1-
and-W2, and then R-to-Y on furnace control thermostat
terminals.
WARNING: Blower access door switch opens 115-v
power to furnace control. No component operation can
occur. Caution must be taken when manually closing this
switch for service purposes. Failure to follow this warn-
ing could result in electrical shock, personal injury, or
death.
NOTE: If thermostat terminals are jumpered at the time blower
access door switch is closed, blower will run for 90 sec before
beginning a heating or cooling cycle.
18. If furnace is operating properly, REMOVE TAPE TO
RELEASE BLOWER ACCESS DOOR SWITCH, and then
replace blower access door.
III. CLEANING HEAT EXCHANGER
The following steps should be performed by a qualified service
technician:
NOTE: If the heat exchangers get a heavy accumulation of soot
and carbon, they should be replaced rather than trying to clean
them thoroughly. A build-up of soot and carbon indicates that a
problem exists which needs to be corrected, such as improper
adjustment of manifold pressure, insufficient or poor quality
combustion air, incorrect size or damaged manifold orifice(s),
improper gas, or a restricted heat exchanger. Action must be taken
to correct the problem.
If it becomes necessary to clean the heat exchangers because of
dust or corrosion, proceed as follows:
1. Turn OFF gas and electrical power to furnace.
2. Remove outer access door.
3. Disconnect vent connector from furnace vent elbow.
4. For downflow or horizontal furnace having an internal vent
pipe, disconnect internal vent pipe within the casing.
5. Disconnect wires to the following components. Mark wires
to aid in reconnection of:
a. Draft safeguard switch.
b. Inducer motor.
c. Pressure switches.
d. Limit overtemperature switch.
e. Gas valve.
f. Hot surface igniter.
g. Flame-sensing electrode
h. Flame rollout switches.
6. Remove screws that fasten the inducer assembly with
backing plate to the cell panel. Be careful not to damage
backing plate. Inducer assembly and elbow need not be
removed from backing plate.
7. Remove burner, gas manifold and support assembly and
NOx devices if present. Individual burners need not be
removed from support assembly.
NOTE: Be very careful when removing burner assembly to avoid
breaking igniter. See Fig. 4 for correct igniter location.
8. Using field-provided small wire brush, steel spring cable,
reversible electric drill, and vacuum cleaner, clean cells as
follows:
a. Assemble wire brush and steel spring cable.
(1.) Use 48 in. of 1/4-in. diameter high-grade steel
spring cable (commonly known as drain clean-out
or Roto-Rooter™ cable).
(2.) Use 1/4-in. diameter wire brush (commonly known
as 25-caliber rifle cleaning brush).
NOTE: The materials needed in items (1.) and (2.) can usually be
purchased at local hardware stores.
(3.) Insert twisted wire end of brush into end of spring
cable, and crimp tight with crimping tool or strike
with ball-peen hammer. TIGHTNESS IS VERY
IMPORTANT.
(4.) Remove metal screw fitting from wire brush to
allow insertion into cable.
b. Clean each heat exchanger cell.
(1.) Attach variable-speed, reversible drill to end of
spring cable (end opposite brush).
(2.) Insert brush end of cable into the outlet opening of
cell and slowly rotate with drill. DO NOT force
cable. Gradually insert at least 36 in. of cable into 2
upper passes of cell. (See Fig. 5.)
(3.) Work cable in and out of cell 3 or 4 times to obtain
sufficient cleaning. DO NOT pull cable with great
force. Reverse drill and gradually work cable out.
TABLE 2—SPEED SELECTOR
COLOR SPEED
FACTORY-
ATTACHED
TO
White Common BLW
Black High COOL
Yellow (When Present) Medium High SPARE
Orange† Medium SPARE
Blue Medium Low HI HEAT
Red Low LO HEAT
† Available on 5-speed blowers only.
—4—

(4.) Insert brush end of cable in burner inlet opening of
cell, and proceed to clean 2 lower passes of cell in
same manner as 2 upper passes.
(5.) Repeat foregoing procedures until each cell in
furnace has been cleaned.
(6.) Using vacuum cleaner, remove residue from each
cell.
(7.) Using vacuum cleaner with soft brush attachment,
clean burner assembly.
(8.) Clean flame sensor with fine steel wool.
(9.) Reinstall burner assembly. Center burners in cell
openings.
9. Remove old sealant from cell panel and inducer backing
plate flange and apply new sealant to flange and reinstall on
cell panel, making sure all screws are secure.
NOTE: A releasing agent such as PAM cooking spray or equiva-
lent (must not contain corn or canola oil, aromatic or halogenated
hydrocarbons or inadequate seal may occur) and RTV sealant
(G.E. 162, 6702, or Dow-Corning 738) are needed before starting
installation. DO NOT substitute any other type of RTV sealant.
G.E. 162 (P771-9003) is available through RCD in 3-oz tubes.
10. Reinstall elbow and inducer assembly.
11. Reconnect wires to the following components (Use connec-
tion diagram on wiring label, if wires were not marked for
reconnection locations.):
a. Draft safeguard switch.
b. Inducer motor.
c. Pressure switches.
d. Limit overtemperature switch.
e. Gas valve.
f. Hot surface igniter.
g. Flame-sensing electrode.
h. Flame rollout switches.
12. Reinstall internal vent pipe, if applicable.
13. Reinstall vent connector on furnace vent elbow. Securely
fasten vent connector to vent elbow with 2 field-supplied,
corrosion-resistant, sheet metal screws located 180° apart.
14. Replace blower access door only.
15. Set thermostat above room temperature and check furnace
for proper operation.
16. Verify blower airflow and speed changes between heating
and cooling.
17. Check for gas leaks.
WARNING: Never use a match or other open flame to
check for gas leaks. Use a soap-and-water solution. A
failure to follow this warning could result in fire, personal
injury, or death.
18. Replace outer access door.
IV. ELECTRICAL CONTROLS AND WIRING
CAUTION: There may be more than 1 electrical supply
to the unit. Check accessories and cooling unit for
additional electrical supplies.
The electrical ground and polarity for 115-v wiring must be
properly maintained. Refer to Fig. 6 for field wiring information
and to Fig. 7 for furnace wiring information.
NOTE: If the polarity is not correct, the STATUS LED on the
control will flash rapidly and prevent the furnace from heating.
The control system also requires an earth ground for proper
operation of the control and flame-sensing electrode.
The 24-v circuit contains an automotive-type, 3-amp fuse located
on the control. (See Fig. 8.) Any shorts of the 24-v wiring during
installation, service, or maintenance will cause this fuse to blow. If
fuse replacement is required, use ONLY a 3-amp fuse. The control
LED will display status code 24 when fuse needs to be replaced.
With power to the unit disconnected, check all electrical connec-
tions for tightness. Tighten all screws on electrical connections. If
any smoky or burned connections are found, disassemble the
connection, clean all parts, and wire conductors, and reassemble
properly and securely.
Reconnect electrical power to the unit and observe unit through 1
complete operating cycle. Electrical controls are difficult to check
without proper instrumentation; if there are any discrepancies in
the operating cycle, contact your dealer and request service.
Fig. 4—Position of Igniter to Burner
A00265
A00266
Fig. 5—Cleaning Heat Exchanger Cell
A91252
—5—

The control in this furnace is equipped with a Light-Emitting
Diode (LED) status code light to aid in installation, servicing, and
troubleshooting. It can be viewed through the sight glass or
window in blower access door. The control indicates status with
the LED on continuously, rapid flashing, or a code composed of 2
digits. The first digit is the number of short flashes, the second
digit is the number of long flashes.
For an explanation of status codes, refer to service label located on
blower access door or Fig. 9, and the troubleshooting guide at the
end of this procedure.
The control stores 5 status codes for a period of 72 hrs.
The stored status codes will NOT be erased from the control
memory, if 115- or 24-v power is interrupted.
1. To retrieve status codes, proceed with the following:
NOTE: NO thermostat signal may be present at control, and all
blower-OFF delays must be completed.
a. Leave 115-v power to furnace turned on.
b. Remove outer access door.
c. Look into blower access door sight glass for current LED
status. Removing blower access door will open blower
access door switch and terminate 115-v power to control
so that status code is not displayed.
d. BRIEFLY remove either wire from the main limit (LS)
or draft safeguard (DSS) switch until LED goes out, then
reconnect it.
NOTE: If wire to LS or DSS is disconnected longer than 4 sec,
main blower starts, and retrieval request is ignored.
2. When above items have been completed, the LED flashes a
status code 4 times. Record this status code for further
troubleshooting.
After the LED flashes a status code four times, BRIEFLY remove
wire again from LS or DSS switch until LED goes out, then
reconnect it to retrieve previous status code (if available). Repeat
as needed for more previous status codes.
3. Operate furnace through 1 heat cycle to test for proper
operation and check LED status.
4. If furnace is operating properly and continuously-lit LED
indicates proper operation, replace outer access door.
5. Component Test can also be initiated by performing the
following:
a. Remove outer access door.
b. Remove blower access door.
c. Manually close blower access door switch.
WARNING: Blower access door switch opens 115-v
power to control. No component operation can occur.
Caution must be taken when manually closing this switch
for service purposes. Failure to follow this warning could
result in electrical shock, personal injury, or death.
d. BRIEFLY short (jumper) TEST/TWIN, 3/16-in. quick-
connect male terminal on control (behind COM-24v
terminal), and COM-24V terminal on furnace control.
(See Fig. 8.)
NOTE: If TEST/TWIN to COM-24V terminals are jumpered
longer than 2 sec, LED will flash rapidly, and test request will be
ignored.
e. Component Test will function as follows.
(1.) LED flashes a status code 4 times. Record this
status code for further troubleshooting.
(2.) Inducer motor starts on high-speed and continues to
run until step (7.) of component test sequence.
(3.) Hot surface igniter is energized for 15 sec, then
de-energized.
(4.) Blower operates at LO-HEAT speed for 10 sec, then
turns off.
(5.) Blower operates at HI-HEAT speed for 10 sec, then
turns off.
(6.) Blower operates at COOL speed for 10 sec., then
turns off.
Fig. 6—Heating and Cooling Application Wiring Diagram
A95236
115-VOLT FIELD-
SUPPLIED
FUSED
DISCONNECT
JUNCTION
BOX
CONTROL
BOX
24-VOLT
TERMINAL
BLOCK
THREE-WIRE
HEATING-
ONLY
FIVE
WIRE
NOTE 2
NOTE 1
1-STAGE
THERMOSTAT
TERMINALS
FIELD-SUPPLIED
FUSED DISCONNECT
CONDENSING
UNIT
FURNACE
COM
R

WC Y RG
GND
GND
FIELD 24-VOLT WIRING
FIELD 115-, 208/230-, 460-VOLT WIRING
FACTORY 24-VOLT WIRING
FACTORY 115-VOLT WIRING
Connect Y/Y2-terminal as shown for proper operation.
Some thermostats require a "C" terminal connection as shown.
If any of the original wire, as supplied, must be replaced, use
same type or equivalent wire.
208/230- OR
460-VOLT
THREE
PHASE
208/230-
VOLT
SINGLE
PHASE
WHT
BLK
WHT
BLK
W/W1
W2
Y/Y2
G
NOTES: 1.
2.
3.
—6—

Fig. 7—Furnace Wiring Diagram A00284
326351-101 REV. B
GV
HI
M
GRN/YEL
C
NOTE #3 BRN
BLU
BRN
GRN/YEL
RED ORN
RED RED
RED
RED
NOTE #11
FRS1 DSS
BVSS
LS
(WHEN USED)
FRS2
NOTE #12
ORN
YEL
HSI
L1 NOTE #2
GND
NEUTRAL
FU2
FUSE OR CIRCUIT
BREAKER & DISCONNECT
SWITCH (WHEN REQ’D)
BLK
ILK
PL5
JB
1 2
SEC-2
LED
SEC-1
FUSE 3-AMP
PLT
ACRDJ
0.5 AMP
@ 24 VAC
HUM
TEST/TWIN
ON
OFF
321
DLY
OFF
LHT
W/W1DHUM G 24V
om
C
W2 Y/ Y2 RY1
TRAN
L1
PR-1
EAC-1
CAP
OL
SPARE - 1
BLWR
BHT/CLR
BHI/LOR
COOL
LO-HEAT
HI-HEAT
START
GRN/YEL
BLWM
NEUTRAL - L2
EAC-2
RED BLU ORN YEL BLK
LO
MED LO
MED
HI
MED HI
RED
BLU
WHT
WHT
BRN
BRN
BLK
WHT
BLK WHT
IHI/LOR
HSIR
IDR
LO
HI
HSI
GRY
CONNECTION DIAGRAM
BLK
1HSI
2
IDM
1
2
3
HI
COM
LO
SCHEMATIC DIAGRAM (NATURAL GAS & PROPANE)
IDR
TO 115VAC FIELD-DISCONNECT SWITCH
ILK EQUIPMENT
GROUND
1 2
3
HSIR
IHI/LOR PL2
L2
L2
CAP
OL
START
BLWM
COM
LO
MED LO
MED
HI
MED HI
LO HEAT
SPARE-2
COOLING
SPARE-1
BHI/LOR
BHT/CLR
BLWR
EAC-2
EAC-1
TRAN
L2
L2
115VAC
24VAC SEC 2
SEC 1
PR1
FU1
NOTE #6
FRS1
DSS
BVSS
FRS2
(WHEN USED)
PL1-8
GVR-2
HUM
RACR PL1-12
HPSR
GV
LPS
NOTE #12
LGPS
(WHEN USED)
HPS
HI
PL1-2
PL1-4
PL1-3
PL1-10
PL1-5
W/W1
CPU
GVR-1
TEST/TWIN
DHUM
W2
Y/Y2
G
Y1
C
OM 24V
NOTE #3
C
M
PL1-1
LPS (WHEN USED)
LGPS
WHT
FSE
FSE
PL1-9 PL1-11
PL1-7
NOTES:
1. If any of the original equipment wire is replaced use wire rated for 105°C. 2. Use only copper wire between the disconnect switch and the furnace junction box (JB). 3. This wire must be connected to furnace sheet metal for control to prove flame. 4. Symbols are electrical representation only. 5. Solid lines inside PCB are printed circuit board conductors and are not included in the legend. 6. Replace only with a 3 amp fuse. 7. Blower motor (BLWM) and inducer motor (IDM) contain internal auto-reset thermal overload switches (OL). 8. Neutral connections are interchangeable within the NEUTRAL connector block. 9. Blower motor speed selections are for average conditions, see installation instructions for optimum selection. 10. MED not available on some models. 11. Factory connected when BVSS (Chimney Adapter Kit) is not installed. 12. Factory connected when LGPS is not used. 13. Ignition lockout will occur after four consecutive unsuccessful trials-for-ignition. Control will auto-reset after three hours. 14. Blower-on delay: gas high-heat 25 seconds, gas low-heat 45 seconds, cooling or heat pump 2 seconds. 15. Blower off-delay: gas heating selections are 90, 120, 150, 180 seconds, cooling or heat pump 90 seconds or
5 seconds when DHUM is on.
LEGEND
ACR AIR CONDITIONING RELAY, SPST (N.O.) ACRDJ AIR CONDITIONING RELAY DISABLE JUMPER BHI/LOR BLOWER MOTOR SPEED CHANGE RELAY, SPDT BHT/CLR BLOWER MOTOR SPEED CHANGE RELAY, SPDT BLWR BLOWER MOTOR RELAY, SPST-(N.O.) BLWM BLOWER MOTOR, PERMANENT-SPLIT-CAPACITOR BVSS BLOCKED VENT SHUTOFF SWITCH, MANUAL-RESET, SPST -(N.C.) CAP CAPACITOR CPU MICROPROCESSOR AND CIRCUITRY DHUM DHUM CONNECTION DSS DRAFT SAFE GUARD SWITCH, AUTO-RESET, SPST -(N.C.) EAC-1 ELECTRONIC AIR CLEANER CONNECTION (115 VAC 1.0 AMP MAX.) EAC-2 ELECTRONIC AIR CLEANER CONNECTION (COMMON) FRS 1, 2 FLAME ROLLOUT SW. -MANUAL RESET, SPST-(N.C.) FSE FLAME-PROVING ELECTRODE FU1 FUSE, 3 AMP, AUTOMOTIVE BLADE TYPE, FACTORY INSTALLED FU2 FUSE OR CIRCUIT BREAKER CURRENT INTERRUPT DEVICE
(FIELD SUPPLIED AND INSTALLED)
GND EQUIPMENT GROUND GV GAS VALVE-REDUNDANT GVR 1, 2 GAS VALVE RELAY, DPST-(N.O.) HPS HIGH-HEAT PRESSURE SWITCH, SPST (N.O.) HPSR HIGH-HEAT PRESSURE SWITCH RELAY, SPST (N.C.) HSI HOT SURFACE IGNITER (115VAC) HSIR HOT SURFACE IGNITER RELAY, SPST (N.O.) HUM 24VAC HUMIDIFIER CONNECTION (0.5 AMP. MAX.) IDM INDUCED DRAFT MOTOR, SHADED-POLE IDR INDUCED DRAFT MOTOR RELAY, SPST-(N.O.) IHI/LOR INDUCER MOTOR SPEED CHANGE RELAY, SPDT ILK BLOWER ACCESS PANEL INTERLOCK SWITCH, SPST-(N.O.) JB JUNCTION BOX LED LIGHT-EMITTING DIODE FOR STATUS CODES LGPS LOW GAS PRESSURE SWITCH, SPST-(N.O.) LPS LOW-HEAT PRESSURE SWITCH, SPST (N.O.) LS LIMIT SWITCH, AUTO-RESET, SPST (N.C.) OL AUTO-RESET INTERNAL MOTOR OVERLOAD TEMPERATURE SWITCH (N.C.) PCB PRINTED CIRCUIT BOARD CONTROL
PL1 12-CIRCUIT PCB CONNECTOR PL2 3-CIRCUIT PCB HSI & IDM CONNECTOR PL3 6-CIRCUIT ICM MOTOR CONNECTOR (NOT SHOWN) PL4 3-CIRCUIT IDM CONNECTOR PL5 2-CIRCUIT HSI CONNECTOR PLT 3-CIRCUIT FACTORY TEST CONNECTOR TRAN TRANSFORMER, 115VAC/24VAC TEST/TWIN COMPONENT TEST & TWINNING TERMINAL
JUNCTION TERMINAL CONTROL PCB TERMINAL FACTORY POWER WIRING (115VAC) FACTORY CONTROL WIRING (24VAC) FIELD CONTROL WIRING (115VAC) FIELD CONTROL WIRING (24VAC) CONDUCTOR ON CONTROL PCB FIELD WIRING SCREW TERMINAL FIELD EARTH GROUND EQUIPMENT GROUND FIELD SPLICE PLUG RECEPTACLE
PCB
ACRDJ
PL1-6
LS
L1
NOTE #10
L2
PL4
PL5
WHT
GRN/YEL
WHT RED
BLK
IDM
COM LO
PL4
1 3 2
HI
WHT
RED
BLK
PL2
IDM
NOTE #8
1 AMP
@ 115 VAC
STATUS CODE
FU1
NOTE #6
PL1 1
SELECT CHART
SW LO-HT
ONLY
BLOWER
OFF-DELAY
ON
OFF
1
ONLY
HEAT
LO
HEAT
NORM 2 3 90
SEC.
ON
OFF
123120
SEC.
ON
OFF
2 3 150
SEC.
ON
OFF
23180
SEC.
HPS
FACTORY SETTINGS
BLW
ORN
HI HEAT
NOTE #11
NOTE #5
*
*
*
SPARE-2
—7—

(7.) Inducer motor goes to low-speed.
Items (1.) through (7.) above will assist in furnace
troubleshooting since all components are function-
ally operated except the gas valve. This procedure is
also referred to as “Component Test Sequence.”
f. Check LED status.
g. If LED status indicates proper operation, RELEASE
BLOWER ACCESS DOOR SWITCH, replace blower
access door, and replace burner access door.
WIRING DIAGRAMS
Refer to Fig. 6 and 7 for wiring diagrams.
TROUBLESHOOTING
Refer to the service label. (See Fig. 9—Service Label.)
The Troubleshooting Guide following Fig. 9 can be a useful tool
in isolating furnace operation problems. Beginning with the word
“Start,” answer each question and follow the appropriate arrow to
the next item.
The Guide will help to identify the problem or failed component.
After replacing any component, verify correct operation sequence.
Fig. 8—Furnace Control
A00380
LHT
OFF
DLY
ON OFF
W2
BLW
24-V-THERMOSTAT
TERMINALS
SETUP SWITCHES
LOW-HEAT ONLY AND
BLOWER OFF-DELAY
TWINNING AND/OR
COMPONENT TEST
TERMINAL
ACRDJ - AIR CONDITIONING
RELAY DISABLE JUMPER
TRANSFORMER 24-VAC
CONNECTIONS
PL1 - LOW VOLTAGE MAIN
HARNESS CONNECTOR
PL3 - ICM CONTROL
HARNESS CONNECTOR
HUMIDIFIER TERMINAL
(24-VAC 0.5 AMP MAX.)
3-AMP FUSE
LED OPERATION &
DIAGNOSTIC LIGHT
115-VAC (L2) NEUTRAL
CONNECTIONS
PL2 - HOT SURFACE
IGNITER & INDUCER
MOTOR CONNECTOR
115-VAC (L1) LINE
VOLTAGE CONNECTION
EAC-1 TERMINAL
(115-VAC 1.0 AMP MAX.)
BLOWER SPEED
SELECTION TERMINALS
HI HEAT
LO HEAT
SPARE-1
SPARE-2 COOL
Y1 DHUM G COM
24V WW1 Y/Y2 R
TEST/TWIN
HUM
1 2 3
PLT
ACRDJ
0.5-AMP024 VAC
FUSE 3-AMP
SEC-1 SEC-2
PL1
NEUTRAL-L2
1
EAC-2
BHT/CLRBHI/LOR
PL3 1
BLWR
COOL
SPARE-1 SPARE-2
1-AMP@115 VAC
EAC-1 PR-1
IDR HSIR
IDM
IHI/LOR
PL2
1
HSI HI LO
S
T
A
T
U
S
C
O
D
E
L
E
D
HI HEAT LO HEAT
L1
—8—

Fig. 9—Service Label
A00286
LED CODE
Ifstatuscode recallisneeded, briefly removethenreconnectonemain limitwire to display stored statuscode.
SERVICE
To initiate thecomponenttestsequence,shutOFF theroom thermostatordisconnectthe "R" thermostatlead.
Brieflyshortthe TEST/TWINterminalto the "Com24V"terminal.StatusLEDwillflashcodeandthen turnON the
inducermotor athigh speed untiltheend ofthe test,then shiftto low speedfor10 seconds.Thehotsurface ignitor,
blower motor low-heatspeed,blower motorhigh-heatspeed,andblowermotorcoolspeed willbeturned ON for
10-15secondseach.GasValve and Humidifierwill not beturned on.
326379-101 REV.A (lit-top)
CONTINUOUSOFF-Check for115VAC atL1andL2,and24VAC atSEC-1and SEC-2.
CONTINUOUSON -Control has 24VACpower.
RAPID FLASHING -Line voltage (115VAC) polarity reversed.Iftwinned,refer to twinningkit instructions.
EACHOF THEFOLLOWINGSTATUS CODESIS ATWO DIGITNUMBERWITHTHE FIRSTDIGITDETERMINEDBYTHE
NUMBER OF SHORTFLASHES AND THE SECOND DIGITBY THE NUMBER OF LONG FLASHES.
STATUS
COMPONENT TEST
11 NO PREVIOUS CODE -Storedstatuscodes areerased automatically after72hours.
12 BLOWER ON AFTERPOWER UP(115 VACor 24VAC)  -Blower runs for 90 seconds, if unit ispowered
upduringacallforheat(R-Wcl
osed).
13 LIMIT,DRAFT SAFEGUARD,FLAME ROLL-OUTSWITCH OR BLOCKED VENTSWITCH 
(when used)
LOCKOUT - Control will autoreset after threehours.Reset switch.Refer to #33.
14 IGNITION LOCKOUT- Control will auto-reset after threehours. Refer to#34.
21 GAS HEATING LOCKOUT - Control will NOTautoreset.
Che
ck for:- Mis-wiredgas valve - Defectivecontrol (valverelay)
22 ABNORMAL FLAME-PROVING SIGNAL- Flameisprovedwhilegasvalveisde-energized. Inducer will run
untilfaultis cleared.Check for:-Leaky gas valve -
Stuck-open gasvalve
23 PRESSURE SWITCH DID NOTOPEN Check for:
- Obstructed pressure tubing. -Pressure switch stuck closed.
24 SECONDARY VOLTAGE FUSEIS OPENCheck for: -Shortcircuitinsecondary voltage(24VAC)wiring.
31 HIGH-HEAT PRESSURESWITCHOR RELAY DIDNOTCLOS E ORREOPENED
Check for: Control relaymay bedefective - Refer to#32
32 LOW-HEAT PRESSURE SWITCH DIDNOT CLOSE OR REOPENED Ifopenlongerthan fiveminutes,
inducershutsofffor15 minutes before retry.Checkfor:-Properventsizing
-D
efective inducermotor - Disconnectedor obstructedpressuretubing
- Excessive wind - Defective pressure switch
- Restrictedvent             -Inadequatecombustionair supply
-Low inducervoltage(115VAC)ifcode flashes whileunitruns inlow-heatwith highspeed inducer.
Ifitopensaftertrialforignitionperiod,blowerwill comeonfor 90second recycle delay.
33 LIMIT,DRAFT SAFEGUA
RD,FLAME ROLL-OUTSWITCH OR BLOCKED VENTSWITCH (when used)
LOCKOUT ISOPEN 
-Ifopen longerthan three minutes,code changes to #13.Flameroll-outswitchrequires
manualreset.Checkfor: -Defective blowermotororcapacitor.
-Dirty filterorrestricted ductsystem. -Restricted vent
-Loose blowerwheel. -Defective switch or connections.
-Properventsizing -Excessive w
ind
-Inadequate combustionairsupply(Flame Roll-outSwitchopen).
-OpenFlameRoll-outswitch.Manualresetorreplace.
34 IGNITIONPROVINGFAILURE - Control willtrythreemoretimesbefore lockout #14 occurs.Ifflamesignal
lostaftertrialforignitionperiod,blowerwillcome on for90second recycledelay.Checkfor:
-Oxidebuildup on flamesensor(cleanwith fine steelwool).
-Properflamesense microamps (.5 m
icroamps D.C.min.,4.0 -6.0nominal).
-Gasvalve defectiveorgasvalve turned off.
- DefectiveHot SurfaceIgnitor  - Manual valveshut-off.
-Low inletgaspressure.  -
Controlground continuity
-Inadequateflame carryoverorrough ignition.-Flamesensormustbe ungrounded.
- Green/Yellowwire MUSTbeconnected tofurnace sheetmetal.
43 LOW-HEAT PRESSURE SWITCH OPEN WHILE HIGH-HEAT PRESSURE SWITCH IS CLOSED
Check for: -Pressure switch stuckopen -Disconnected orobstructed pressure tubing
45 CONTROLCIRCUITRY LOCKOUT 
Auto-resetafterone hourlockoutdueto;
- Flamesense circuit failure     - Softwarecheckerror    - Gas valverelaystuckopen
Resetpowerto clearlockout.Replace controlifstatus coderepeats.
A00286
—9—

A00231a
Is circuit breaker closed? Close door switch and go to start.Is LED status light on? Is door switch closed?
Is LED status light blinking rapidly without a pause?
Is there 115v going to switch? Replace door switch.Replace control center. Replace transformer.
Is LED status light blinking ON/OFF slowly with a combination of short and long flashes?
Check for correct line voltage polarity. If units are twinned, check for proper low-voltage (24v) transformer phasing. To recall status code briefly remove then reconnect one RED wire from the Draft Safeguard Switch to display stored status code.You can also recall the previous status code by momentarily shorting the TEST/TWIN terminal and the COM24V terminal until the LED goes out. LED will flash the status code of the previous fault or the code No. 11 (1 short and 1 long flash) if no previous fault. After the control repeats the code 4 times, the control will go through a brief component test sequence. The inducer will start at high speed and run for the entire component test then shift to low speed for 10 seconds. The HSI, blower motor low-heat speed, blower motor high-heat speed, and blower motor cool speed will run for 10-15 sec each. Gas valve and humidifier will not be turned on.
Determine status code. The status code is a 2 digit number with the first digit determined by the number of short flashes and the second digit by the number of long flashes.
Was there a previous fault code other than No. 11?
Does control respond to W/W1, W2, Y1, Y/Y2, or G 24-vac thermostat signals? Run system through a low-heat, high-heat or cooling cycle to check operation. Status codes are erased after 72 hrs.
Go to section with status code determined.
Is there 115v at L1 and L2?
Close circuit breaker and go back to start.
Check for continuity in wire from circuit breaker to furnace.
NO NO NO
NO NO
NO
YES
YES YES
YES YES
YES
YES
NO
NO YES YES
YES
START
Is there 24v at SEC-1 and SEC-2?
NO Is 24 vac present at W/W1, W2, Y1,
Y/Y2, or G terminals on the control? Replace control if it does not respond to 24-vac signal at W/W1, W2, Y1, Y/Y2, or G screw terminals. Check room thermostat or interconnecting cable.
YES NO
NO
Troubleshooting Guide
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A00231b
11 NO PREVIOUS FAULT - Faults are
erased after 72 hrs. Run system through a low-heat, high-heat or cooling cycle to check system.
12 BLOWER ON AFTER POWER
UP (115V OR 24V) - Normal operation. Blower will run for 90 sec when furnace power is interrupted during a call for heat, R-W closed.
13 LIMIT, DRAFT SAFEGUARD, FLAME
ROLLOUT SWITCH OR BLOCKED VENT SWITCH (WHEN USED) LOCKOUT - Any of these switches was open longer than 3 minutes. Auto-reset will occur after 3 hrs. Flame rollout switch or blocked vent switch (when used) requires manual reset. See No. 33
14 IGNITION LOCKOUT - System
failed to ignite gas and prove flame in 4 attempts. Control will auto-reset in 3 hrs. See No. 34
21 GAS HEATING LOCKOUT -
Turn off power and wait 5 minutes to retry. Check for:
Unplug igniter harness from control and inititate another component test sequence. Check for 115v between pins 1 and 2 on the control. Was 115v present for the 17-sec period?
Replace control.
Check for continuity in the harness and igniter. Replace defective component.
Reconnect the R thermostat lead and set thermostat to call for heat. Connect voltmeter across gas valve connections. Does gas valve receive 24v?
Check connections. If OK, replace control.
Does gas valve open and allow gas to flow?
Check that all gas valves are turned on. Replace valve.
Do main burners ignite? Do main burners stay on? Allow blower to come on and repeat test to check for intermittent operation.
Repeat call for heat and check flame sensor current during trial for ignition period. Is the DC microamps below 0.5?
Check connections and retry. If current is near typical value and burners will not stay on, replace control.
Clean flame sensor with fine steel wool and recheck current. Current is nominally 4.0 to 6.0 microamps. Is current near typical value? Replace electrode. Will main burner ignite and stay on? Replace control. Fixed.
• Stuck closed gas valve relay
on control.
• Miswire or short to gas valve
wire.
22 ABNORMAL FLAME PROVING
SIGNAL - Flame was sensed while gas valve was de-energized. Inducer will run until fault is cleared. Check for:
• Stuck open gas valve solenoid
or leak.
23 PRESSURE SWITCH DID
NOT OPEN - Check for:
• Disconnected or obstructed
pressure tubing.
• Defective pressure switch.
24 SECONDARY VOLTAGE FUSE IS
OPEN - Check for: • Short in low-voltage wiring
including thermostat leads shorting to ductwork or furnace cabinet. Disconnect thermostat leads to isolate short circuit.
32 LOW-HEAT PRESSURE SWITCH
DID NOT CLOSE OR REOPENED - If open longer than 5 minutes, inducer shuts off for 15 minutes before retry. Check for:
• Proper vent sizing or pitch or
sag.
• Vent restrictions or high winds. • Defective inducer motor. • Low line voltage (115v). • Low inlet gas pressure (if LGPS
used).
• Defective pressure switch or
connections. If it opens after trial for ignition period, blower will come on for 90 sec recycle delay.
• Inadequate combustion air.
33 LIMIT, DRAFT SAFEGUARD, FLAME
ROLLOUT SWITCH OR BLOCKED VENT SWITCH (WHEN USED) IS OPEN - If any switch is open longer than 3 minutes, code changes to No. 13. Check for:
• Blower motor failure. • Motor start capacitor. • Open flame rollout switch, manual reset. • Dirty filter or restricted duct system. • Defective limit switch or connections. • Loose blower wheel.
34 IGNITION PROVING FAILURE -
If flame is not sensed during the trial for ignition period, the control will repeat the ignition sequence 3 more times before going into lockout, No. 14. If flame signal is lost after trial for ignition period, blower will come on for 90-sec recycle delay. Check for the following items first before proceeding to the next step.
• Gas valve turned off. • Manual shut-off valve. • Green/Yellow wire must be
connected to furnace sheet metal.
To determine whether the problem is in the gas valve, igniter, or flame sensor, the system can be operated in the component test mode to check the igniter. First, remove the R thermostat connection from the control and initiate the component test sequence. Does the igniter glow orange/white hot by the end of the 15-sec warm-up period?
Check for:
• Inadequate flame carryover or
rough ignition.
• Low inlet gas pressure.
NO
YES
YES YES YES YES YES
YES YES YES
NO NO
NO NO NO NO NO
•Inadequate combustion air supply
(flame rollout switch open).
NO
• Restricted vent. • Proper vent sizing. • Excessive wind.
45 CONTROL CIRCUITRY LOCKOUT
- Auto-reset after one hour. Lockout due to: • Flame-sense circuit failure. • Gas valve relay stuck open • Software check error Reset power to clear lockout. Replace control if status code repeats.
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© 2000 Bryant Heating & Cooling Systems 7310 W. Morris St. Indianapolis, IN 46231 —12— Printed in U.S.A. SP0468 Catalog No. 5331-201