Well first you want to verify that there is gas pressure coming from the connector. Turn off the valve and disconnect the connector. Then turn on the valve for 1 second and back off. You should get plenty of gas flow. Be careful doing this!. Then inspect the opening at the adapter to the control. There is a screen inside there. Make sure the screen is clear(not plugged with pipe dope,lint ect). When the igniter reaches the 2200 degrees you should hear the gas solenoid valve click open releasing gas. If you hear it click and no gas is released you will need to inspect the burner orfices. The orfice has an extremely small hole and there is a posibillity that they are plugged with debris. You will need to use a very small wire(like a tie strap) and insert it into each hole and see if there is anything in the orfice. If you do not hear the gas valve click then it might not be getting the signal it needs due to a weak igniter or flame rectification sensor. Does your furnace have a stand-by pilot that is lit by the hot surface igniter or does the igniter directly light the burner assembly?
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thats not even relavent
Add a Commentits a 40 old furnace
its forty years old noignitor
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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 (or circuit breaker ) 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 (use gloves). 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.
sends a signal to the control module. The control module will indicate a call for heat with a light on the control either blinking or remain solid depending upon model. The inducer (exhaust) blower will purge all gasses from the furnace and pressurize a pressure switch. Once the pressure switch tells the module to continue, the electronic ignition will energize and send 120 volts to the ignitor. The ignitor will glow and you will be able to see it if viewed thru the small inspection port. Once the ignitor gets hot enough, it sends a signal to the module opening up the gas valve (24 volts). Either a pilot will come on or the burner tube will ignite then spread the flame to all burners. Lastly a safety sensor will be looking for a certain temperature within a few seconds and the furnace will continue to operate and the room air blower will turn on in a minute or two. 249 views
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