Form I-UDA, P/N 195673 Rev 13, Page 37
PROBLEM (cont'd)
PROBABLE CAUSE (cont'd)
REMEDY (cont'd)
Burner will not light
(cont'd)
4.
No Spark (cont'd):
4.
(cont'd)
c) Incorrect spark gap.
c) Maintain spark gap at 1/8".
d) Spark cable shorted to ground.
d) Replace worn or grounded spark cable.
e) Spark electrode shorted to ground.
e) Replace if ceramic spark electrode is cracked or grounded.
f) Burner not grounded.
f) Make certain integrated circuit board is grounded to ignitor.
g) Circuit board not grounded.
g) Make certain integrated circuit board is grounded to furnace chassis.
h) Unit not properly grounded.
h) Make certain unit is properly field grounded to earth ground and properly
phased (L1 to hot lead L2 to neutral).
i)
Integrated circuit board fuse blown.
i) Correct cause. Replace fuse (type ATC or ATO, 32VDC, 3A).
j) Faulty integrated circuit board.
j) If 24 volt is available to the integrated circuit board and all other causes
have been eliminated, replace board.
5.
Lockout device interrupting control circuit by above
causes.
5.
Reset lockout by interrupting control at the thermostat or main power.
6.
Combustion air proving switch not closing.
6.
a) Make sure unit is
properly vented.
b) Remove obstructions from vent.
c) Replace faulty tubing to pressure switch.
7.
Faulty combustion air proving switch.
7.
Replace combustion air proving switch.
8.
Main valve not operating.
8.
a) Defective valve.
a) If 24 volt is measured at the valve connections and valve remains closed,
replace valve.
b) Loose wire connections
b) Check and tighten all wiring connections.
9.
Integrated circuit board does not power main
valve.
9.
a) Loose wire connections.
a) Check and tighten all wiring connections.
b) Flame sensor grounded.
b) Be certain flame sensor lead is not grounded or insulation or ceramic is
not cracked. Replace as required.
c) Incorrect gas pressure.
c) Supply pressure should be 5" - 14" w.c. for natural gas or 11" - 14" w.c.
for propane gas.
d) Cracked ceramic at sensor.
d) Replace sensor.
Burner cycle on and
off
1.
Gas pressure too high or too low.
1.
Supply pressure should be 5" - 14" w.c. for natural gas or 11" - 14" w.c.
for propane gas.
.
Burner not grounded
.
Make certain integrated circuit board is grounded to ignitor.
3.
Circuit board not grounded.
3.
Make certain integrated circuit board is grounded to furnace chassis.
4.
Faulty integrated circuit board
4.
If 24 volt is available to the integrated circuit board and all other causes
have been eliminated, replace board.
5.
Combustion air proving switch not closing.
5.
a) Make sure unit is properly vented.
b) Remove obstructions from vent.
c) Replace faulty tubing to pressure switch.
6.
Faulty combustion air proving switch.
6.
Replace combustion air proving switch.
7.
Flame sensor grounded.
7.
Be certain flame sensor lead is not grounded or insulation or ceramic is
not cracked. Replace as required.
8.
Cracked ceramic at sensor.
8.
Replace sensor.
9.
Incorrect polarity.
9.
Reverse line volt leads to integrated circuit board.
10.
Pin terminal loose on 9 pin plug.
10.
Replace wire harness.
No heat (Heater Op-
erating)
1.
Incorrect valve outlet pressure or orifice.
1.
Check valve outlet pressure. See Rating plate for manifold pressure.
.
Cycling on limit control.
.
Check air throughput.
3.
Improper thermostat location or adjustment.
3.
See thermostat manufacturer's instructions.
Fan or venter motor
will not run
1.
Circuit open.
1.
Check wiring and connections.
.
Defective integrated circuit board.
.
Replace board.
3.
Defective motor or starter.
3.
Replace motor or starter.
Fan or venter motor
turns on and off while
burner is operating
1.
Motor overload device cycling on and off.
1.
Check motor load against motor rating plate. Replace motor if needed.
Fan or venter motor
cuts out on overload
1.
Low or high voltage supply.
1.
Correct electric supply.
.
Defective motor.
.
Replace motor.
3.
Poor airflow.
3.
Clean motor, fan, fan guard, filter, and coils