Bryant 394HAD Furnace User Manual


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