COZY CDV155D - Troubleshooting Your Furnace

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TROUBLESHOOTING YOUR FURNACE
ISSUE
1. Pilot will not stay lit after
carefully following lighting
instructions.
2. Pilot burning - no gas to
the main burner.
3. Burner comes “ON” but goes
“OFF” after operating for no
apparent reason.
4. Furnace operates, but turns
“OFF” before room temperature
is attained.
5. Furnace not producing
su󰀩cient heat.
6. Furnace operates, but will not
shut “OFF” when room
temperature is attained.
POSSIBLE CAUSE(S)
A. Generator producing
insu󰀩cient millivolts.
B. Generator defective.
C. Loose or dirty generator
connections at gas valve.
D. Grounded thermostat lead wire.
E. Defective gas valve.
A. Valve not turned to “ON”
position after lighting the pilot.
B. Thermostat not turned to a
position calling for heat.
C. Plugged burner orice.
D. Improperly wired or broken
thermostat wires.
Defective thermostat.
E. Pilot generator may not be
generating su󰀩cient millivolts
to open valve.
F. Defective valve.
A. Tubes not properly installed.
B. Furnace may be overrated.
A. Thermostat location.
B. Defective thermostat.
A. Furnace may be too small for
space being heated.
B. Furnace not burning at full rate.
A. Thermostat wiring defective.
B. Thermostat location.
CORRECTIVE ACTION
Check the pilot ame. It must impinge on the generator. Be sure the
generator is fully inserted in the bracket. Make sure the pilot lighting
door is tightly closed.
Check generator with millivolt meter. Take reading at generator
terminals of valve with pilot burning and thermostat contacts closed.
The reading should be 140 millivolts or more.
Clean and/or tighten connections at valve.
Remove thermostat lead wires from valve terminals. If the pilot now
stays lit, trace the thermostat wiring circuit for a ground. May be
grounded to the furnace, gas supply, nails or staples.
Replace the gas valve after the above is veried.
Turn the gas valve knob to the “ON” position.
Set the thermostat to a position calling for heat.
Check - clean or replace.
Check the connections at the valve terminals. Jumper across the
thermostat terminals on the valve. If the valve operates, check the
thermostat wires.
See 1A and 1C above.
Replace the gas valve after above is veried.
Check the vent tube and the air inlet tube. Follow the installation
instructions. Be sure the joints are tight and both tubes are in place.
Use only the tubes furnished. Do not extend the tubes beyond
original length.
Check for high pressure at the valve. See rating plate for specied
min./max. supply pressure. Check the burner orice.
Check the thermostat location. It should not be in the path of warm
air discharge from the furnace, near a lamp or above a T.V. or
stereo set.
Check the thermostat calibration or replace.
Check heat calculations.
Check for low gas pressure. Check the burner orice.
Thermostat lead wires may be shorted together, by a nail or staple.
Check by removing thermostat leads from the valve terminals.
Check the thermostat location. If on an outside wall or there is a
hole in the wall behind the thermostat causing cold air to contact the
thermostat. Relocate the thermostat.
For qualied service technicians.