Troubleshooting Chart - Williams 6008532 Owner's Manual

Troubleshooting
FOR MODELS: 6008532; 6008531
SYMPTOM
1. Pilot w ill not stay lit
after follow ing lighting
instructions.
2. Main burner w ill not
come ON - pilot
burning and
thermostat set for
heat.
3. Burner comes "ON"
but goes OFF before
blow er turns ON.
4. Burner comes "ON",
blow er comes "ON",
but cycles "ON"
and "OFF" w hile
burner remains "ON".
5. Burner comes "ON",
blow er comes "ON",
but burner cycles
"OFF" and "ON" w ith
blow er "ON".
6. Furnace operates but
turns "OFF" before
room temperature is
attained.
POSSIBLE CAUSE
A. Thermocouple producing
insufficient millivolts.
B. Loose or dirty
thermocouple
connection at gas valve.
C. Thermocouple defective.
D. Thermomagnet pilot
safety defective
E. Vent safety shutoff
device.
A. Gas valve not turned ON
after lighting the pilot.
B. Electric pow er to furnace
turned OFF.
C. Low voltage transformer
or limit sw itch defective.
D. Wall thermostat
defective.
E. Burner orifice plugged.
F. Gas valve defective.
A. Defective w iring.
B. Defective limit sw itch.
C. Defective motor (2-
speed).
D. Defective motor (1-
speed).
E. Detective fan sw itch.
A. Furnace not operating at
full rate.
A. Furnace operating over-
rate.
B. Line voltage too low .
C. Recirculation.
D. Loss of circulating air
due to leakage.
A. Thermostat location.
B. Defective thermostat.
Check pilot flame – it must impinge on thermocouple. Pilot flame may be low or
blow ing (high) causing safety to drop out. Pilot orifice or aerating hole may be plugged
(check for spiders, w ebs or other organic material). Be sure the thermocouple is fully
inserted in its bracket.
Clean and/or tighten the thermocouple fitting at the connection to the valve.
Check thermocouple w ith millivolt meter – it should generate approximately 30
millivolts w hen not connected to a load. When connected to a load, it should generate
approximately 14 millivolts. If below 7 millivolts, replace.
Replace gas valve after above is checked out.
Check w iring connections from valve to the vent safety shutoff device. Be sure all
connections are tight. Check for blocked or incorrect venting.
Turn gas valve knob to 'ON" position - if no main gas flow , proceed to Step. "B".
Check for line voltage at furnace - if okay and no main gas flow , proceed to Step "C".
Check for 24 volts at the low voltage terminals of the transformer. If no voltage,
OFF electric pow er to furnace. Remove one w ire from limit sw itch and check for
continuity across both terminals. No continuity – replace limit sw itch. With a good limit
sw itch back in the circuit and the electric pow er turned ON - if no voltage, replace
transformer. NOTE: Before replacing the transformer or limit sw itch, check w iring for
loose connections or broken w ires and repair as needed. If voltage is present at
transformer, proceed to Step "D".
With thermostat set for heat (contacts closed) check for voltage at terminals on gas
valve. If no voltage is present replace defective thermostat. NOTE: Before replacing
thermostat, be sure to check the w iring from the furnace to thermostat for loose
connections or broken w ires and replace as needed.
Clean or replace orifice - if okay and still no gas flow to main burners, proceed to Step
"F".
Replace defective gas valve.
Turn OFF electric pow er to furnace. Remove top front panel, fan shroud and blow er
w heel. Refer to Wiring Diagram and check all w iring inside junction
center front panel and check all w iring inside sw itch box containing fan, limit and
selector sw itches. Correct if necessary. If correct, proceed to Step "B".
If burner goes OFF in less than five minutes from room temperature start, check limit
control sw itch. If detective, replace. NOTE: Blow er should turn "ON" w ithin three
minutes after burner is "ON" from a room temperature start. If not, proceed to Step
"C".
Jumper across the fan switch, turn electric pow er ON, the motor should rotate. If a 2-
speed motor is used - jumper from "brow n" terminal on the fan sw itch to #2 (red)
terminal on the selector sw itch, motor should rotate on "LOW" speed. Jumper from
same "brow n" terminal on the fan sw itch to #3 (black) terminal on the selector sw itch,
motor should rotate on "HIGH" speed. Replace motor if defective.
Jumper across fan switch, turn electric power ON, motor should rotate. Replace motor
if detective.
If, after checking above possibilities, problem still exists, replace fan sw itch.
Check for low gas pressure at gas valve - should be 4" W.C. for Natural Gas, 11" W.C.
for L.P. Gas. Check burner orifice.
Check for high gas pressure at gas valve - correct if necessary. See correct pressure
above.
Check line voltage to motor, if below 115 volts motor w ill run too slow .
Heated air discharging against an object causing recirculation, such as a hall
installation or a large piece of furniture w ithin 4' of discharge.
Check header plate installation and proper use of gaskets. Repair as necessary.
Check location of thermostat. It should not be in the path of w arm air discharge from
the furnace, near a lamp, or above a TV set or stereo.
Check thermostat calibration or replace.
CORRECTIVE ACTION
Care – 29
turn
box. Remove