York SUNLINE MagnaDRY WR300 Installation Manual page 72

284813-YIM-C-1008
The draft motor runs but the furnace does not light and
the sparker does not spark.
1. The ignition control (IC1, IC2) may be locked out
due to either a flame roll out or 100% shut off.
These safety features are described above. If lock-
out has occurred, 24V must be removed from the
ignition controls. This is done at the unit or by
resetting the room thermostat. After resetting 24V,
check for proper furnace operation. If lock-out con-
tinues to occur, locate the source of the problem
and correct.
2. Check all 24 volt connections from the relay board
to and in the gas heat section. Check low voltage
connections to the (ETD) located in the control
box.
3. If the furnace is hot, it may be out on an over-tem-
perature condition, wait for limit reset.
4. 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.
5. 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-attach 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 centrifu-
gal 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.
6. 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.
7. 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 electri-
cal 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.
72
The draft motor runs and the ignitor sparks at the pilot
burner but the pilot does not ignite and a gas odor is
not detected at the draft motor outlet.
1. 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" page 63 and that the pilot
adjust screw is allowing some flow of gas as
described in "PILOT CHECKOUT" page 64.
2. Check all wiring between the ignitor control and the
gas valve. Check to make sure the ground connec-
tions are intact.
3. If the wiring is intact, check for 24 volts across ter-
minals "PV" and "COMMON" on the ignitor control.
If 24 volts is not present, replace the ignitor control.
4. 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.
The ignitor sparks at the pilot burner but the pilot does
not ignite and a gas odor is detected at the draft motor
outlet.
1. Adjust the pilot adjust screw on the gas valve as
described in "PILOT CHECKOUT" page 64.
2. Check the supply pressure as described in "POST
START CHECK LIST" page 63. Make adjustments
as necessary.
3. Check the pilot orifice and carryover tube for
obstruction as described in paragraph above.
Clean as needed but the problem should not be the
gas valve.
The pilot burner ignites but the ignitor continues to
spark and the main burners do not ignite.
1. Make the same checks and adjustment as
described in "PILOT CHECKOUT" page 64.
2. Check the supply pressure as described in "POST
START CHECK LIST" page 63. Make adjustments
as necessary.
3. Make sure that the pilot burner is not bent or dam-
aged.
Johnson Controls Unitary Products