When you turn the thermostat on the wheel on the draft unducer will spin for a minute or so but stops spinning. The furnace doesnt light
If the inducer runs for a short time and shuts off and the main blower comes on and runs it could be a high limit switch or a roll out switch.it could also be a pressure switch that is stuck in the closed position. Most new furnaces have to read the pressure switch in the open position and then the closed position after the inducer fan starts. . Hope this helps.
1. Thermostat calls for heat.
2. Draft inducer motor starts.
3. Pressure switch attached by a small plastic or rubber tube senses the negative pressure produced by the draft inducer and closes.
4. Draft inducer runs for 30 seconds to a minute before you hear a gas hissing sound. The ignitor did not glow, the flame sensor (a small metal probe about 1/8" in diameter, with a white porcelain base) does not sense the flame, so after 8 to 10 seconds the hissing sounds stops with no ignition of gas to heat your home. Your furnace shuts down and goes into a lock out condition until you turn your power switch back off and on again. Then the sequence starts all over again with no ignition of the gas.
Solution:You probably need to purchase and install a new ignitor. I would suggest that you inspect your ignitor closely for cracks.Make sure you do not touch the ignitor with your bare hands. If you do not visually see a crack, then you could have a furnace control board problem or a limit, rollout switch problem. Please see "limits, rollout switches & furnace control boards" further down on this page. The furnace's control board might not be supplying the voltage to the ignitor. If your furnace lights and the gas stays on for 8 to 10 seconds, then shuts right back off, then you need to clean your flame sensor with light sand paper or steel wool. You might need a new flame sensor, but most of the time they can be cleaned an will work well after cleaning.
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1. Thermostat calls for heat.
2. Draft inducer motor starts.
3. Pressure switch attached by a small plastic or
rubber tube senses the negative pressure produced by
the draft inducer and closes.
4. Draft inducer runs for 30 seconds to a minute
before you hear a gas hissing sound. The ignitor did
not glow, the flame sensor (a small metal probe about
1/8" in diameter, with a white porcelain base) does not sense the flame, so after 8 to 10 seconds the hissing sounds stops
with no ignition of gas to heat your home. Your
furnace shuts down and goes into a lock out condition
until you turn your power switch back off and on
again. Then the sequence starts all over again with no ignition of the
gas.
Solution: You
probably need to purchase and install a new ignitor. I would suggest that you
inspect your ignitor closely for cracks. Make sure
you do not touch the ignitor with your bare hands. If
you do not visually see a crack, then you could have a furnace control board
problem or a limit, rollout switch problem. The furnace's
control board might not be supplying the voltage to the ignitor. If
your furnace lights and the gas stays on for 8 to 10 seconds, then shuts right
back off, then you need to clean your flame sensor with light sand paper or
steel wool. You might need a new flame sensor, but most of the time they can be
cleaned an will work well after cleaning.
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Does the motor get hot before it shuts off? Do you hear any splashing of water in the housing while its running?
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