Nortron D SERIES Installation And Operating Instructions Manual - page 10
The first step in identifying an operational problem is to determine
whether the fault is in the furnace or in the thermostat and/or its
connecting wiring.
To help make this determination, the furnace is equipped with a
“Thermostat ON” diagnostic light. If the light is “ON”, it indicates
the thermostat has closed and is calling for heat; the blower
should be running. If the light is “OFF”, the furnace should not be
operating (unless the Continuous Speed switch is set to run the
motor continuously).
1. If the furnace will not start:
Turn the thermostat to its highest setting. If the light goes on,
the thermostat has closed, so the fault is in the furnace. If the
light does not go on, the thermostat or its connecting wiring is
the problem.
2. If the furnace will not turn off:
Turn the thermostat to its lowest setting. If the light goes off and
the furnace continues to run, the thermostat has opened properly
and the fault is in the furnace. If the light stays on, the fault is
in the thermostat or its connecting wiring.
After the fault area is isolated by use of the diagnostic light, a check
of the following components can be made more efficiently.
TROUBLESHOOTING
PROBLEM
POSSIBLE DEFECTIVE PARTS OR COMPONENTS
1. The furnace will not turn on
• Thermostat
• Circuit breaker or fuse is open
• Motor or capacitor
• Fan control switch
• Electronic control
• Transformer
2. Motor runs continuously
•
Continuous Speed switch is not on “Off” position
• Thermostat wires incorrectly attached to furnace
3. Elements on, but motor does not run
• Motor or capacitor
• Electronic control
4. Motor going on and off in short cycles
(or in too long cycles)
• Heat anticipator in thermostat incorrectly set
or may be defective
5. Must set thermostat much higher (or lower)
than the desired house temperature
• Thermostat is not leveled or out of calibration
6. Not enough heat
• One or more defective elements or relays
•
Season Select switch in “Mild” positio
n
• Safety limits opening because duct obstruction
or dirty filters are restricting air flow
• Defective or incorrectly wired two-stage
or outdoor thermostat
• Lack of enough cold air returns in house
7. Two-stage or outdoor thermostat not operating properly •
Season Select switch not in “Mild” positio
n
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