Bryant 394Had Users Manual

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2015-02-02

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service and
maintenance procedures

394HAD
396HAD
Series C

GAS-FIRED
INDUCED-COMBUSTION FURNACES
Cancels:

SP04-13

SP04-19
11-1-93

NOTE: Read the entire instruction manual before starting the
installation.

→ These procedures are for sizes 65,000 through 150,000 Btuh units.
Index

Page

ama

CANADIAN GAS ASSOCIATION

A PP R O VED
R

SAFETY CONSIDERATIONS .....................................................1
CARE AND MAINTENANCE..................................................1-5
Air Filter Arrangement..........................................................2-3
Blower Motor and Wheel......................................................3-4
Cleaning Heat Exchanger......................................................4-5
Electrical Controls and Wiring.................................................5
Pilot ...........................................................................................5
Troubleshooting ........................................................................5
Unit Wiring Diagram ............................................................6-7
Troubleshooting Chart ..............................................................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. All other operations must
be performed by trained service personnel. When working on
heating equipment, observe precautions in the literature, on tags,
and on labels attached to or shipped with the unit and other safety
precautions that may apply.

A92058

Fig. 1—Model 396HAD
Downflow

Follow all safety codes. In the United States, follow all safety
codes including the National Fuel Gas Code NFPA No. 541992/ANSI Z223.1-1992 (NFGC). In Canada, refer to the current
edition of the National Standard of Canada CAN/CGA-B149.1and .2-M91 Natural Gas and Propane Gas Installation Codes
(NSCNGPIC). Wear safety glasses and work gloves. Have fire
extinguisher available during start-up and adjustment procedures
and service calls.

A92057

Fig. 2—Model 394HAD Upflow
WARNING: The ability to properly perform maintenance on this equipment requires certain expertise, 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 recommended in the User’s Manual. FAILURE TO FOLLOW
THIS WARNING COULD RESULT IN POSSIBLE
DAMAGE TO THIS EQUIPMENT, SERIOUS PERSONAL INJURY, OR DEATH.

Recognize safety information. 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 word DANGER, WARNING, or CAUTION. 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 that 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 that will result in enhanced installation, reliability, or
operation.

CARE AND MAINTENANCE
For continuing high performance and to minimize possible equipment failure, it is essential that periodic maintenance be performed
on this equipment. Consult your local dealer as to the proper
frequency of maintenance and the availability of a maintenance
contract.
—1—

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.

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.

1. Downflow
Each furnace requires 2 filters which are installed in the
return-air duct. (See Fig. 3.)

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.

AIRFLOW
INSTALLATION
POSITION
OF FILTERS
RETURN-AIR
PLENUM

The minimum maintenance that should be performed 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 and lubrication each heating and cooling season. Clean and lubricate as
necessary.
3. Check electrical connections for tightness and controls for
proper operation each heating season. Service as necessary.
CAUTION: As with any mechanical equipment, personal injury can result from sharp metal edges, etc.,
therefore, be careful when removing parts.

ACCESS DOOR

A88486

Fig. 3—Filter Positions

Air Filter Arrangement

The air filter arrangement may vary depending on the application.
Refer to Table 1 or 2 for filter size information.

To remove filters for cleaning or replacement, proceed as
follows:
a. Disconnect electrical power before removing access
door.

TABLE 1—FILTER SIZE INFORMATION FOR DOWNFLOW FURNACE (IN.)

b. Remove blower access door after removing 2 screws.

FURNACE
CASING WIDTH
14-3/16
17-1/2
21
24-1/2

FILTER QUANTITY
AND SIZE
(2) 16 X 20 X 1
(2) 16 X 20 X 1
(2) 16 X 20 X 1
(2) 16 X 20 X 1

c. Reach up behind top plate, tilt filters toward center of
return-air plenum, remove filters, and clean as needed.
Replace if torn.

FILTER
TYPE
Cleanable
Cleanable
Cleanable
Cleanable

d. Furnaces are equipped with permanent, washable filters.
Clean filters with tap water. Spray water through filter in
opposite direction of airflow.
e. Rinse and let dry. Oiling or coating of filters is not
recommended or required.
f. Reinstall filters.

TABLE 2—FILTER SIZE INFORMATION FOR UPFLOW
FURNACE (IN.)
FURNACE
CASING WIDTH
14-3/16
17-1/2
21
24-1/2

FILTER QUANTITY AND SIZE
Side Return
Bottom Return
(1) 16 X 25 X 1* (1) 14 X 25 X 1
(1) 16 X 25 X 1* (1) 16 X 25 X 1
(1) 16 X 25 X 1 (1) 20 X 25 X 1*
(2) 16 X 25 X 1* (1) 24 X 25 X 1

g. Replace access door and secure with 2 screws.
h. Restore electrical power to furnace.

FILTER
TYPE

2. Upflow
Each furnace requires 1 or 2 filters which are installed in the
blower compartment. (See Fig. 4.)
To remove filters for cleaning or replacement, proceed as
follows:
a. Disconnect electrical power before removing access
doors.

Cleanable
Cleanable
Cleanable
Cleanable

* Factory provided with the furnace. Filters may be field modified by cutting as
required.

—2—

MOUNTING
SCREWS
DRAFT
SAFEGUARD
SWITCH
RELIEF
BOX

FLUE
COLLECTOR
BOX

SPEED
SELECTOR

GAS
VALVE

MOUNTING
SCREWS

AUXILIARY
LIMIT SWITCH
(NOT VISIBLE)
VENT PIPE
ENCLOSURE

CONTROL
BOX

PILOT
CONTROL
BOX

DRAFT
SAFEGUARD
SWITCH

RELIEF
BOX

SPEED
SELECTOR

FLUE
COLLECTOR
BOX

FILTER
RETAINER
WASHABLE
FILTER

A92178

A92179

Fig. 5—Model 396HAD Downflow

Fig. 4—Model 394HAD Upflow
b. Remove blower and control access doors.

3. Disconnect wires from auxiliary limit on blower housing
(downflow furnace only).

c. Release filter retainer from clip at front of furnace
casing. (See Fig. 4.) For side return, clips may be used on
either or both sides of the furnace.

4. Remove control box.
5. Remove electrical leads from numbered side of blower
speed selector. (See Fig. 4 and 5.) Note location of wires for
reassembly.

d. Slide filter out.
e. Furnaces are equipped with permanent, washable filters.
Clean filters with tap water. Spray water through filter in
opposite direction of airflow.

6. Remove screws holding blower assembly to blower deck
and slide blower assembly out of furnace.

f. Rinse and let dry. Oiling or coating of filter is not
recommended or required.

7. Squeeze side tabs of blower speed selector and pull it out of
blower housing.

g. Reinstall filter.

8. Loosen screw in strap holding motor capacitor to blower
housing and slide capacitor out from under strap.

h. Replace access doors.
i. Restore electrical power to furnace.

9. Mark blower wheel, motor, and motor support in relation to
blower housing before disassembly to ensure proper reassembly.

B. Blower Motor and Wheel
For long life, economy, and high efficiency, clean accumulated dirt
and grease from the blower wheel and motor annually.
The following steps should be performed by a qualified service
technician:
Some motors have prelubricated sealed bearings and require no
lubrication. These motors can be identified by the absence of oil
ports on each end of the motor. For those motors with oil ports,
lubricate motor every 5 years if motor is used on intermittent
operation (thermostat FAN switch in AUTO position), or every 2
years if motor is in continuous operation (thermostat FAN switch
in ON position).
Remember to disconnect the electrical supply before removing
access doors.

10. Loosen setscrew holding blower wheel on motor shaft.
11. Remove bolts holding motor mount to blower housing and
slide motor and mount out of housing. Disconnect ground
wire attached to blower housing before removing motor.
12. Lubricate motor (when oil ports are provided).
a. Remove dust caps or plugs from oil ports located at each
end of motor.
b. Use a good grade of SAE 20 nondetergent motor oil and
put 1 teaspoon, 5 cc, 3/16 oz, or 16 to 25 drops in each
oil port. Do not over-oil.
c. Allow time for total quantity of oil to be absorbed by
each bearing.

Clean and lubricate as follows:

d. Wipe excess oil from motor housing.

1. Remove 2 screws from blower access door (downflow
furnace only). Remove blower access door.

e. Replace dust caps or plugs on oil ports.
13. Remove blower wheel from housing.
a. Mark cutoff location to ensure proper reassembly.

2. Remove vent pipe enclosure (downflow furnace only) and
disconnect short piece of vent pipe from relief box.
—3—

b. Remove screws holding cutoff plate and remove cutoff
plate from housing.

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).

c. Lift blower wheel from housing through opening.
14. Clean blower wheel and motor using a vacuum cleaner 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.

(2.) Use 1/4-in. diameter wire brush (commonly known
as 25-caliber rifle cleaning brush).
NOTE: The items needed in steps (1.) and (2.) can usually be
purchased at local hardware stores.
(3.) Insert twisted wire end of brush into end of steel
spring cable, and crimp tight with crimping tool or
strike with ball-peen hammer. TIGHTNESS is very
important.

15. Reinstall blower wheel by reversing steps 13 a. through c.
Be sure wheel is positioned for proper rotation.
16. Reassemble motor and blower by reversing steps 5 through
11. If motor has ground wire, be sure it is connected as
before.

(4.) Remove metal screw fitting from wire brush to
allow insertion into cable.
b. Clean each heat exchanger cell.

CAUTION: Be sure the motor is properly positioned in
the blower housing. The motor oil ports must be at a
minimum of 45° above the horizontal centerline of the
motor after the blower assembly has been reinstalled in
the furnace.

(1.) Attach variable-speed, reversible drill to end of
steel spring cable (end opposite brush).
(2.) Insert brush end of cable into upper 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. 6.)

17. Reinstall blower assembly in furnace. Connect electrical
leads to blower speed selector. Please note that connections
are polarized for assembly. DO NOT FORCE.
18. Reinstall control box.
19. Reconnect wires to auxiliary limit switch on blower housing
(downflow furnaces only).
20. Reinstall vent pipe and enclosure (downflow furnaces
only).
21. Turn on electrical power and check for proper rotation and
speed changes between heating and cooling.
22. Replace blower access door and secure with 2 screws
(downflow furnace only).
C. Cleaning Heat Exchanger
The following steps should be performed by a qualified service
technician:
NOTE: Deposits of soot and carbon indicate the existence of a
problem which needs to be corrected. Take action to correct the
problem.
If it becomes necessary to clean the heat exchanger because of
carbon deposits, soot, etc., proceed as follows:

A91252

Fig. 6—Cleaning Heat Exchanger Cell
(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.
(4.) Remove burner assembly and cell inlet plates.

1. Turn off gas and electrical power to furnace.

(5.) Replace screws in center panel and cells before
cleaning.

2. Remove 2 screws from blower access door (downflow
furnace only). Remove control and blower access doors.

(6.) Insert brush end of cable in lower opening of cell,
and proceed to clean 2 lower passes of cell in same
manner as 2 upper passes.

3. Remove vent pipe enclosure (downflow furnace only) and
disconnect vent pipe from relief box.
4. Remove 2 screws that secure relief box. (See Fig. 4 or 5.)

(7.) Repeat foregoing procedures until each cell in
furnace has been cleaned.

5. Disconnect wires to the following components:
a. Draft safeguard switch

(8.) Remove residue from each cell using vacuum
cleaner.

b. Inducer motor

(9.) Clean burner assembly using vacuum cleaner with
soft brush attachment.

c. Pressure switch
d. Limit overtemperature switch

(10.) Reinstall cell inlet plates and burner assembly.
Care must be exercised to center the burners in the
cell openings.

e. Gas valve
f. Edge connector leading to control box
6. Remove 8 screws that secure flue collector box to center
panel. Be careful not to damage sealant.

9. After cleaning flue openings, check sealant on flue collector
to ensure that it has not been damaged. If new sealant is
needed, contact your dealer or distributor.

7. Remove complete inducer assembly from furnace, exposing
flue openings.

10. Clean and replace flue collector assembly, making sure all
8 screws are secure.

8. Clean cells using field-provided small wire brush, steel
spring cable, reversible electric drill, and vacuum cleaner.

11. Reinstall 2 screws in relief box.
—4—

12. Reconnect wires to the following components:
a. Draft safeguard switch

PILOT HEAD V–NOTCH FALLS
DIRECTLY BELOW FRONT EDGE
OF BURNER CARRYOVER.

b. Inducer motor
c. Pressure switch
d. Limit overtemperature switch
e. Gas valve
f. Edge connector leading to control box
1/8″

13. Reconnect vent pipe to relief box. Replace vent pipe
enclosure (downflow furnace only).
14. Replace blower access door only and secure with 2 screws
(downflow furnace only).
15. Turn on electrical power and gas.
16. Set thermostat and check furnace for proper operation.

A91249

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.

Fig. 7—Position of Pilot to Burner

Pilot

Check the pilot and clean if necessary at the beginning of each
heating season. The pilot flame should be high enough for proper
impingement of the flame sensing element (or thermocouple) and
to light the burners. Remove the accumulation of soot and carbon
from the flame sensing element (or thermocouple). Refer to Fig. 7
for proper location of pilot on burner assembly.

17. Check for gas leaks.
18. Replace control access door.
D. Electrical Controls and Wiring
NOTE: There may be more than 1 electrical supply to unit.
The electrical ground for 115-v wiring must be maintained
properly. Refer to Fig. 8 for field wiring information and to Fig. 9
for unit wiring information.
With power disconnected to unit, check all electrical connections
for tightness. Tighten all screws on electrical connections. If any
smoky or burned connections are noticed, disassemble the connection, clean all parts and stripped wire, and reassemble properly and
securely. Electrical controls are difficult to check without proper
instrumentation; therefore, reconnect electrical power to unit and
observe unit through 1 complete operating cycle.
The 24-v circuit contains an automotive-type, 3-amp fuse located
on the main control board. Any direct shorts during installation,
service, or maintenance could cause this fuse to blow. If fuse
replacement is required, use ONLY a 3-amp fuse of identical size.

Troubleshooting

Page 8 contains a troubleshooting chart. This chart 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 chart will help identify the problem or failed component. After
replacing any component, verify correct operating sequence as
indicated by bold arrows.

—5—

FIELD 24-VOLT WIRING
FIELD 115-, 208/230-, 460-VOLT WIRING
FACTORY 24-VOLT WIRING
FACTORY 115-VOLT WIRING
W

FOUR
WIRE

THERMOSTAT
TERMINALS

FIELD-SUPPLIED
FUSED DISCONNECT

TWO-WIRE
HEATINGONLY
BLK

BLK

WHT

GND

115-VOLT FIELD- AUXILIARY
J-BOX
SUPPLIED
CONTROL
FUSED
BOX
DISCONNECT

208/230- OR
460-VOLT
THREE
PHASE

G
C

GND

CONDENSING
UNIT

24-VOLT
TERMINAL
BLOCK
FURNACE

208/230VOLT
SINGLE
PHASE

TWO
WIRE
NOTE: Connect Y-terminal as
shown for proper
operation.

NOTE: If any of the original wire,
as supplied, must be replaced, use
same type or equivalent wire.

A78461

Fig. 8—Heating and Cooling Application Wiring Diagram

—6—

—7—

BLWM
CAP
CFR
DSS
EAC-1
EAC-2
FU1
FU2
FL
GV
HFR
IDM
IDR
ILK
JB
LS
PCB
PL1
PL2
PL4
PRS
TRAN

LEGEND
ALS

CAP

BRN

BLWM

FU2

ILK
NOTE #5

EAC-2

EAC-1

NOTE #10

HFR

TRAN

CFR
LO

COM
PR2 L2

PL2
BLK 1
2
WHT

AUX. LIMIT SWITCH (OVER TEMP), SPST-(N.C.),
MANUAL RESET
BLOWER MOTOR
CAPACITOR
COOLING FAN RELAY, SPDT
DRAFT SAFEGUARD SWITCH, SPST-(N.C.), MANUAL RESET
ELECTRONIC AIR CLEANER CONNECTION (115VAC)
ELECTRONIC AIR CLEANER CONNECTION (COMMON)
FUSE, 3 AMP, AUTOMOTIVE BLADE TYPE
FUSE, FIELD INSTALLED
FUSIBLE LINK
GAS VALVE, (REDUNDANT)
HEATING FAN RELAY, SPST (N.O.)
INDUCED DRAFT MOTOR
INDUCER DRAFT RELAY, DPST-(N.O.)
BLOWER DOOR INTERLOCK SWITCH, SPST-(N.O.)
JUNCTION BOX
LIMIT SWITCH (OVER TEMP), SPST-(N.C.), AUTO RESET
PRINTED CIRCUIT BOARD (FURNACE CONTROL)
9-CIRCUIT CONNECTOR (PCB1)
2-CIRCUIT CONNECTOR (L1, L2)
5-CIRCUIT PLUG CONNECTOR (BLWM)
PRESSURE SWITCH, SPDT
TRANSFORMER (115VAC/24VAC)

BRN

GRN

NOTE #4
PL4
4
3 RED
2
BLK
1
WHT
C

LO
MED LO
MED HI
HI
COM

GRN

WHT

BLK

FUSED DISCONNECT
SWITCH (WHEN REQ'D)

IDM
RED
WHT

BLK

WHT

(WHEN USED)
NOTE #7

ALS

BLU

NOTE #9

PR1

BLK

PILOT

BLK

DSS

IDR

3AMP
FUSE
NOTE #8

FU1

PL1 1 4 7
2 5 8
3 6 9

GROUND
SCREW
REQ'D

SEC-1

SEC-2

BLU
BRN
ORN

PLUG RECEPTACLE

FIELD SPLICE

EQUIPMENT GROUND

PCB

HFR

NOTE #1

PL1-6

CFR

PRS

EAC-2

PL1-4

COM

IDR

DSS

NOTE #10

4
3
2
1
C

FU1

PR-1

TRAN

115VAC

BLWM

HFR

PILOT

IDR

MGV GV

TIME
DELAY

LOGIC

PL1-8

SEC-2

PR-2

IDM

SCHEMATIC
DIAGRAM

3A
SEC-1 24VAC
FUSE
NOTE#8

PL1-1

PL1-3

CAP

LO
MED LO
MED HI
HI
COM

PL4
NOTE#4

PL1-2

(WHEN USED)
NOTE #7

ALS

EAC-1

CFR

EQUIPMENT GROUND

TO 115V AC FIELD DISCONNECTIONS
NOTE #5

PL1-9

NO
NC

IDR

NOTE#10

A92176

NOTES:
1. INTERNALLY CONNECTED TO EQUIPMENT GROUND THROUGH MOUNTING SCREW.
2. IF ANY OF THE ORIGINAL EQUIPMENT WIRE IS REPLACED, USE WIRE RATED FOR
105° C.
3. BLOWER MOTOR (BLWM) & INDUCER MOTOR (IDM) CONTAIN AUTO-RESET
THERMAL OVERLOAD SWITCH.
4. BLOWER MOTOR FACTORY SPEED SELECTIONS (PL4) ARE FOR AVERAGE
CONDITIONS. SEE INSTALLATION INSTRUCTIONS FOR DETAILS ON OPTIMUM
SPEED SELECTIONS.
5. USE ONLY COPPER WIRE BETWEEN THE DISCONNECT SWITCH AND THE
FURNACE JUNCTION BOX (JB).
6. SYMBOLS ARE ELECTRICAL REPRESENTATIONS ONLY.
7. AUXILIARY LIMIT SWITCH (ALS) USED ON DOWNFLOW MODELS ONLY.
8. THE TRANSFORMER 24VAC WINDING IS PROTECTED BY A 3 AMP AUTOMOTIVE
BLADE TYPE FUSE ON THE CONTROL BOARD. A 24VAC SHORT TO GROUND
DURING INSTALLATION, CHECKOUT, OPERATION, SERVICE OR MAINTENANCE
COULD CAUSE THIS FUSE TO OPEN. DO NOT REPLACE THE 3 AMP FUSE
WITH ANY OTHER SIZE FUSE.
9. BLOWER MOTOR (BLWM) ADJUSTABLE OFF-DELAY. FACTORY SET: 120 SECS.
CUT RESISTOR: 180 SECS.
10. WHEN CFR RELAY IS ENERGIZED, HFR RELAY IS ALSO ENERGIZED.
319593-401 REV. C

PL1-7

PL2

ILK

Fig. 9—Unit Wiring Diagram

FIELD WIRING SCREW TERMINAL
FIELD GROUND

NOTE #1

PRS

JUNCTION
TERMINAL
PCB TERMINAL
FACTORY POWER WIRING (120VAC)
FACTORY CONTROL WIRING (120VAC)
FIELD POWER WIRING (120VAC)
CONDUCTOR ON PCB

BRN

BLK

GV
MGV

BLU
RED

WHT
RED
RED

CONNECTION
DIAGRAM

YEL

START
Turn on 115-VAC
power to unit.

Disconnect all thermostat
wires from board.

Turn off 115-VAC
power to unit.

Is blower
running?

Is 24VAC
across screws
R & C?

YES

Is
115VAC
across HI &
COM?

YES

Replace
board.

YES

YES
Replace
board.

YES
NO

YES

Is
115VAC
across L1 &
L2?

YES

Replace
board.

YES

Is 24VAC
across pressure
switch N/O contact
& screw C on
board?

Repair wire
harness.

Check/Replace:
1. Vent systems
2. Induce wheel
3. Flue choke
4. Inducer voltage
5. Inducer motor bearings

Jumper across
screws R & W.

Is heat
exchanger
pressure drop greater
than 0.35-in.
wc?

YES

Check/Replace:
1. 3-amp board
fuse
2. Transformer

Is
24VAC
across PL1-2
& screw C on
board?

YES
Does
blower turn
off?

Check/Replace:
1. Unit power
2. Door switch
3. Power harness

Check pressure
tube for leak or
crimp; otherwise,
replace pressure switch

Remove
R & G jumper.

Is
24VAC
across screws
R & C?

YES

Replace
blower motor
and/or start
capacitor.

Is
115VAC
across EAC-1
& COM?

YES

Is 24VAC
across screws
W & C or
G & C?

Check/Replace:
1. Limit switch
2. Limit shield (if used)
3. Fuse link
4. Auxillary limit switch (if used)
5. Wire harness

Jumper across
screws R & G.

Is
blower running
on cooling
speed?

YES

Are
all thermostat
wires to board
disconnected?

Is 24VAC
across pressure
switch N/O contact
& screw C on
board?

YES

Check/Replace:
1. Draft safeguard switch
2. Wire harness

NO
Is
inducer motor
on?

YES

Is
unit lit?

Replace
inducer motor.

YES

Check/Repair
wire harness;
otherwise,
replace
pressure
switch.

Is
24VAC across gas
valve?

YES

Check/Replace:
1. Pilot
2. Thermocouple
3. Gas valve

YES
Is
blower running
on heat speed 45
sec after unit
lights?

Is
115VAC across
inducer motor
connector?

YES

Is
24VAC
across
PL-1 & screw
C on board?

Is
115VAC
across EAC-1
& COM?

Replace
blower motor
and/or start
capacitor.

YES

Replace
board.

YES

Replace
board.

YES

Is
24VAC across
PL-2 & screw
C on board?

Is
115VAC across
inducer motor
connector?

Remove
R & M jumper.

Check/Replace
thermostat
and/or
thermostat wiring.

Repair wire
harness.

NO
NO

After
off-delay
does blower
turn off?

YES

Reconnect all
thermostat wires.

Does unit
operate?

NOTE: After replacing any component, verify correct operating
sequence as indicated by bold arrows.

YES
END OF TEST.

A91253

Printed in U.S.A.

—8—

35001b

Catalog No. BDP-3339-432

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Create Date                     : 2005:11:10 11:32:29-05:00
Metadata Date                   : 2005:11:10 11:32:29-05:00
Document ID                     : uuid:598d41bd-a1f5-4cab-8a5a-e2eb9c17c49d
Instance ID                     : uuid:42b4fa81-ef73-4341-9018-23cec9cceb94
Page Count                      : 8
Author                          : Carrier Corporation

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Bryant 394Had Users Manual

394HAD to the manual 5f1fcab9-8ae2-4f48-bf65-1b78f880b70d

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