A00231b
11
NO PREVIOUS F
A
UL
T - F
aults are
er
ased after 72 hrs
. Run system through
a lo
w-heat, high-heat or cooling cycle to
chec
k system.
12
BLO
WER ON AFTER PO
WER
UP (115V OR 24V) - Nor
mal
operation. Blower will run for 90
sec when furnace power is
interrupted during a call for heat,
R-W closed.
13
LIMIT
, DRAFT SAFEGU
ARD
, FLAME
R
OLLOUT SWITCH OR BLOCKED
VENT
SWITCH (WHEN USED) LOCK
OUT -
An
y of these s
witches was open longer
than 3 minutes.
Auto-reset will occur after
3 hrs. Flame rollout s
witch or b
loc
ked v
ent
switch (when used) requires manual reset.
See No. 33
14
IGNITION LOCK
OUT - System
failed to ignite gas and prove
flame in 4 attempts. Control will
auto-reset in 3 hrs.
See No. 34
21
GAS HEA
TING LOCK
OUT -
Turn of
f power and wait 5
minutes to retry
.
Check for:
Unplug igniter harness from control
and inititate another component test
sequence. Check f
or 1
15v between
pins 1 and 2 on the control. W
as 1
15v
present f
or 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
bu
rners will not stay on, replace
control.
Clean flame sensor with fine steel w
ool 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 PR
O
VING
SIGNAL - Flame w
as 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
NO
T OPEN - Chec
k f
or
:
•
Disconnected or obstructed
pressure tubing.
•
Defective pressure switch.
24
SECOND
AR
Y
V
O
LT
A
GE FUSE IS
OPEN - Chec
k f
or
:
•
Short in low-voltage wiring
including thermostat leads
shorting to ductwork or
furnace cabinet. Disconnect
thermostat leads to isolate
short circuit.
32
LO
W
-HEA
T PRESSURE SWITCH
DID NO
T CLOSE OR REOPENED
- If open longer than 5 minutes,
inducer shuts of
f 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 (1
15v).
•
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 SAFEGU
ARD
, FLAME
R
OLLOUT SWITCH OR BLOCKED
VENT
SWITCH (WHEN USED) IS OPEN - If an
y
switch is open longer than 3 min
utes
, code
changes to No
. 13.
Chec
k f
or
:
•
Blower motor failure.
•
Motor start capacitor
.
•
Open flame rollout switch, manual reset.
•
Dirty filter or restr
icted duct system.
•
Defective limit switch or connections.
•
Loose blower wheel.
34
IGNITION PR
O
VING F
AILURE -
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 of
f.
•
Manual shut-of
f valve.
•
Green/Y
ello
w 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
•
Restr
icted v
ent.
•
Proper v
ent sizing.
•
Excessiv
e wind.
45
CONTR
OL CIRCUITR
Y LOCK
OUT
-
A
uto-reset after one hour
. Loc
kout
due to:
• Flame-sense circuit f
ailure
.
• Gas v
alv
e rela
y stuc
k open
• Softw
are chec
k error
Reset po
w
er to clear loc
kout.
Replace control if status code
repeats
.
—11—
