If lock-out continues to occur, locate the source of the
problem and correct.
b. Check all 24 volt connections from the relay board to
and in the gas heat section. Check low voltage connec-
tions to the (ETD) located in the control box.
c. If the furnace is hot, it may be out on an over-tempera-
ture condition, wait for limit reset.
d. If the furnace is cold, check for 24 volts at wire 241
attached to the electrical time delay (ETD) located in the
main control box. If 24 volts is not found, replace the
ETD.
e. 24 volts is found at wire 241, remove the wires attached
to the (TDR) and with a VOM, check for continuity
across contacts 1 and 2. If none is found, the (TDR) is
open and must be replaced. If there is continuity, re-at-
tach the wires.With the draft motor running, check for
24 volts at terminal 4 of (RW1-2) and (RW2-1). If 24 volts
is not present, the centrifugal switch (CS) has not closed
or has gone bad. Check the line voltage to the unit - if
it is correct, replace the draft motor. If line voltage is low,
call the power company.
f.
Check for 24V at terminal 2 of (RW1-2 and RW2-1). If
24V is not present, check for 24V at (RW1 and RW2)
relay coils. If these relays are pulled in, then check for
a loose connection at terminal 2 and terminal 4 of each
relay. If no problem is found, then replace (RW1 and/or
RW2) as required.
g. If 24 volts is present at the ignitor controls, check all
control wiring at the ignitor controls and the high tension
wire to the ignitors. Check that the ground wires from
the ignitor controls, the gas valves and pilot burners are
all intact and making good electrical connection. Check
to make sure that the ceramic insulator on the pilot
ignitors or sensors is not broken or cracked, if all are
intact, replace the ignition control IC1 or IC2.
5. The draft motor runs and the sparker sparks at the pilot
burner but the pilot does not ignite and a gas odor is not
detected at the draft motor outlet.
a. Check to make sure gas is being supplied to the unit.
Make sure that the gas pressure to the unit is within the
proper limits as described in the “POST START CHECK
LIST” and that the pilot adjust screw is allowing some
flow of gas as described in “PILOT CHECKOUT”.
b. Check all wiring between the ignitor control and the gas
valve. Check to make sure the ground connections are
intact.
c. If the wiring is intact, check for 24 volts across terminals
“PV” and “COMMON” on the ignitor control. If 24 volts
is not present, replace the ignitor control.
d. If 24 volts is present, remove the pilot burner and
remove the pilot orifice from the pilot burner. The orifice
is removed in the direction opposite the flow of gas.
Inspect the orifice for obstruction. If it is clear, replace
the main gas valve.
6. The sparker sparks at the pilot burner but the pilot does not
ignite and a gas odor is detected at the draft motor outlet.
a. Adjust the pilot adjust screw on the gas valve as de-
scribed in “PILOT CHECKOUT”.
b. Check the supply pressure as described in “POST
START CHECK LIST”. Make adjustments as necessary.
c. Check the pilot orifice for obstruction as described in
para. 5d. Clean as needed but the problem should not
be the gas valve.
7. The pilot burner ignites but the sparker continues to spark
and the main burners do not ignite.
a. Make the same checks and adjustment as described in
para. 6.
b. Make sure that the pilot burner is not bent or damaged.
c. Make sure that the ground connections at the pilot
burner, gas valve and ignitor control are intact. Check
the high tension wire for good electrical connection. If
all are intact, replace the ignitor module.
8. The pilot burner lights and the spark stops but the main
burners do not light.
a. Check electrical connections between the ignitor con-
trol and the gas valve. If intact, check for 24 volts across
terminals “MV” and “COMMON” terminals. If no voltage
detected, replace ignitor control. If voltage is present,
replace gas valve.
9. Furnace lights with roll-out or one burner has delayed
ignition.
a. Make sure that the pilot burner is aligned properly with
the carryover as described in “PILOT CHECKOUT”.
b. Make sure that the carryovers on adjoining burners are
screwed fast and are level with respect to one another.
10. Main burners light but exhibit erratic flame characteristics.
a. Adjust air shutters as described in “BURNER AIR
SHUTTER ADJUSTMENT”.
b. Check the main burner orifices for obstruction and
alignment. Removal procedure is described in
“BURNER INSTRUCTIONS”. Clean or replace burner
orifices and burners as needed.
TROUBLESHOOTING
- Cont’d.
530.18-N6Y
Unitary Products Group
23
