2.The supply air blower operates but the draft motor does not when the room thermostat is set to call for heat and the fan switch in the “ON” position.
a.The draft motor has inherent protection. If the motor shell is hot to the touch, wait for the internal overload to reset.
b.If the motor shell is cold with the room thermostat calling for heat, check for line voltage at the motor’s
c.If line voltage is not present, check for line voltage at the draft motor relay "DMR" or "DMC" contacts in the main control box and check to see if the “DMR” or "DMC" is pulled in.
d.If the “DMR” or "DMC" relay is pulled in, check for a loose line voltage connection.
e.If the “DMR” or "DMC" relay is not pulled in, check for 24 volts at the “DMR” or 24 volts at the
3.The draft motor runs but the furnace does not light and the sparker does not spark.
a.Check all 24 volt connections from the relay board to and in the gas heat section. Check low voltage connec- tions to the “BT” and "DMC" or "ETD" located in the control box.
b.If the furnace is hot, it may be out on an over tempera- ture condition, wait for limit reset.
c.With the draft motor running, check for 24 volts at terminal 24V on the ignitor control (IC) where the red lead from the draft motor attaches. 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.
d.If 24 volts is present at the ignitor control, check all control wiring at the ignitor control and the high tension wire to the ignitor. Check that the green ground wires from the ignitor control, the gas valve and pilot burner are all intact and making good electrical connection. Check to make sure that the ceramic insulator on the pilot ignitor or sensor is not broken or cracked, if all are intact replace the ignition control “IC”.
4.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.
5.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 Item 4. Clean as needed but the problem should not be the gas valve.
6.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 Item 5.
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.
7.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.
8.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.
9.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.
208/230, 460 VOLT | 208/230, 575 VOLT | |||
MODELS ONLY | MODELS ONLY | |||
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MODELS ONLY
Unitary Products Group |
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P.O. Box 1592, York, Pennsylvania USA |
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Subject to change without notice. Printed in U.S.A. | ||
Copyright © by York International Corporation 1998. All Rights Reserved. | ||
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