Troubleshooting Chart - Bryant 394HAD Service And Maintenance Procedures Manual

Gas-fired induced-combustion furnaces series c
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Turn on 115-VAC
power to unit.
Jumper across
screws R & G.
blower running
NO
Replace
across EAC-1
board.
R & G jumper.
NO
Jumper across
screws R & W.
inducer motor
YES
115VAC across
Replace
inducer motor
inducer motor.
NO
24VAC across
PL-2 & screw
Check/Repair
wire harness;
otherwise,
replace
pressure
switch.
NOTE: After replacing any component, verify correct operating
sequence as indicated by bold arrows.
© 1993 BDP Co. • P.O. Box 70 • Indianapolis, IN 46206
YES
Is blower
running?
NO
Check/Replace:
1. Limit switch
2. Limit shield (if used)
3. Fuse link
4. Auxillary limit switch (if used)
5. Wire harness
Is
NO
on cooling
speed?
YES
Is
115VAC
& COM?
Check pressure
YES
crimp; otherwise,
Remove
replace pressure switch
Does
blower turn
pressure drop greater
off?
YES
Check/Replace:
1. Vent systems
2. Induce wheel
3. Flue choke
4. Inducer voltage
5. Inducer motor bearings
Is
YES
on?
NO
Is
on heat speed 45
connector?
NO
Is
NO
C on board?
YES
Replace
board.
NO
Printed in U.S.A.
START
Disconnect all thermostat
wires from board.
Is 24VAC
YES
across screws
R & C?
NO
Is
NO
115VAC
across HI &
COM?
YES
Replace
blower motor
and/or start
capacitor.
tube for leak or
YES
Is heat
exchanger
YES
switch N/O contact
than 0.35-in.
wc?
NO
switch N/O contact
NO
Is
24VAC across gas
unit lit?
YES
Is
blower running
NO
sec after unit
lights?
YES
Is
115VAC
across EAC-1
& COM?
YES
Remove
R & M jumper.
After
YES
off-delay
does blower
turn off?
—8—
Is 24VAC
YES
across screws
W & C or
G & C?
NO
Is
YES
115VAC
across L1 &
L2?
NO
Check/Replace:
1. Unit power
2. Door switch
3. Power harness
Is
24VAC
across PL1-2
& screw C on
board?
NO
YES
Is 24VAC
across pressure
& screw C on
board?
NO
Is 24VAC
YES
across pressure
Check/Replace:
1. Draft safeguard switch
& screw C on
2. Wire harness
board?
NO
Check/Replace:
Is
YES
1. Pilot
2. Thermocouple
valve?
3. Gas valve
Is
YES
115VAC across
inducer motor
connector?
NO
Is
24VAC
YES
across
PL-1 & screw
C on board?
NO
Repair wire
harness.
Reconnect all
thermostat wires.
35001b
Catalog No. BDP-3339-432
Turn off 115-VAC
power to unit.
NO
Are
all thermostat
wires to board
disconnected?
YES
Replace
board.
YES
Is
24VAC
across screws
R & C?
NO
Check/Replace:
1. 3-amp board
fuse
2. Transformer
NO
Replace
board.
Repair wire
harness.
Replace
blower motor
and/or start
capacitor.
Replace
board.
Check/Replace
thermostat
and/or
thermostat wiring.
NO
Does unit
operate?
YES
END OF TEST.
A91253

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