need help diagnosing furnace not lighting

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Old 10-27-11, 02:14 PM
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need help diagnosing furnace not lighting

I am very new to furnaces but not to home improvement.

I have an ICP gas furnace with the model number NTC6075FBA1.

I turn the thermostat on and increase the temp to 70*
the blower motor then starts up
then nothing, it will continue to blow cold air until i turn the thermo down or off

I have a tester and basic electrical knowledge. I have turned the gas and electricity off to the appliance and also removed the fuse to prevent accidental start up. Please help me figure out what I need to do next.
 
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Old 10-27-11, 08:09 PM
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Start by taking the cover ofrf the burner compartment of the furnace.

Describe in detail the SEQUENCE of events that you see happening when the thermostat is turned up. The accuracy and completeness of your description will determine how much help we can be.
 
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Old 10-28-11, 02:00 PM
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I did that is all that happens the intake motor starts up and then just spins no clicking no gas sound.
 
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Old 10-28-11, 02:49 PM
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Not sure about that particular model but many furnaces have a peep hole window in the blower door. If yours does, there could very well be a light blinking a code. Note the code & remove the blower compartment door. On the inside of the door on the control itself should be a key to the code.
 
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Old 10-28-11, 06:05 PM
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Follow Grady's directions to check for a diagnostic code.


The odds are the pressure switch isn't closing, which means that something in the heat exchanger or venting system is plugged up.

Besides following Grady' advice, use your tester to check on whether the pressure switch is closed when the inducer motor is running.

Connect your tester to the furnace chassis (sheet metal) ground and check for voltage on the two pressure switchy connections. You'll probably find voltage on one side but not the other, indicating that the switch isn't closing.

If you get voltage on both sides, it is closing and something else is the problem.
 
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Old 10-29-11, 06:55 AM
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Well I decided to see what would happen if I turned the furnace on with the ignition/sensor unplugged. Well this time....

the intake motor and the blower motor both started
the pressure switch clicked
the intake and blower motors began blowing slightly slower
pressure switch clicked
gas started leaking out the pilot pipe

This tells me that the problem must be the ignition or the sensor correct?

also there are no blinking lights on the entire system
 
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Old 10-29-11, 07:53 AM
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yes, sounds like you have a Honeywell SMART (dumb) valve and either the valve is bad or your ignitor is bad....
 
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