30
2. Element life is reduced somewhat by repeated heating and cooling. If the furnace is to be used
again within a few hours, it is best to keep it at the operating temperature or at a reduced level
such as 500°F (260°C).
3. Change the thermocouple every six months.
Troubleshooting
The Troubleshooting Tips section is intended to aid in defining and correcting possible service problems.
When using the chart, select the problem category that resembles the malfunction. Then proceed to the
possible causes category and take necessary corrective action.
PROBLEM PROBABLE CAUSE CORRECTIVE ACTION
The power light does not illuminate. The furnace is not connected to
power supply.
ON and OFF power switch is
defective.
Check furnace connection to power
source.
Replace power switch.
The furnace does not heat, cycle
light illuminated.
Heating elements burned out or
improper connections.
Replace heating elements or repair
connections.
The furnace does not heat, cycle
light not illuminated.
No power.
Two or more heating elements in
208V or 240V furnaces are burned
out.
Thermocouple has oxidized and
opened the circuit. Indicated by:
a) basic automatic control - 1-5
degrees on display
b) automatic control - "OR" on
display.
c) Prog. 2 ramp & 2 dwell -
"SNB" on display.
d) Prog. 8 ramp & 8 dwell -
"OR" on display.
Defective electrical hookup.
Set point set too low.
High power limit set to a low level.
Door switch malfunction.
Defective mechanical door switch
relay coil or contacts.
Check power source and fuses or
breakers.
Replace defective elements.
Replace thermocouple.
Repair electrical hookup.
Reset setpoint to a higher value.
Reset level to a higher value.
Re-align or replace door safety
switch.
Replace relay.
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