Question about Air Conditioners
Here is the sequence I see.
I ask for heat. The combustion exhaust fan comes on. The ignighter glows. As the glow fades, I hear the gas valve clicking open but as if it is too late, it turns off, never firing the burners. I smell a hint of propane at this point.
However, if when I hear the valve kick on I BLOW THE GAS THROUGH, THE BURNERS IGNITE! - and the system stays on until the demand for heat is satisfied. But, next time, If I am not there to blow on it, the system attampts to light 3 x and on the last fail, the house blower fan comes on. I can only turn it off by cutting current to the unit. This also re-sets the unit to go through another 3 cycle attempt to fire.
It is as if the igniter and the gas valve are no longer in synck.
The error code is 2 flashes - system lockout (no flame) check line polarity.
Again, if I blow the gas to the fading glow of the igniter, the unit fires and continues to work just fine so I guess all the limiters and safery circuits are functional
The unit worked fine for years. Then a few times, we just turned the power off and it fired the next time. Now it seems the delay got worse.
Is there a way to re-set the cirquit board? any suggestions or revelations on what is wrong? Any questions to clarify my problem? Please ask. I have a multi-tester and can read wiring diagrams and usually manage to fix things myself. This time I need help. Thank you in advance for providing it.
Put your hand on the gas valve and see if the click of the valve is opening just before the ignitor goes off if it does your valve is going bad
Posted on Nov 13, 2008
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Jan 07, 2011 | Air Conditioners
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.
Dec 07, 2010 | Air Conditioners
When there is a Call for heat, the control delays ignition until combustion air
Blower operation has been proved and pre-purge period
Has elapsed. It then opens the gas valve and generates a
Spark to ignite the burners. Trial for ignition lasts for 7 seconds.
At the same time, the control begins monitoring the
Flame sensor. If the flame current is too weak (less than 1
Micro amp) or if the burners do not ignite (within the 7 second
Ignition trial), the control will shut off spark and the combustion
Air blower and de-energize the gas valve. Flame
Current should be between 1 and 5 micro amps to keep the
Gas valve open.
The control will attempt to ignite the burners up to two more
Times. Each time the control restarts the ignition sequence,
It begins with a 45 second pre-purge. If flame is not sensed
After the third trial, the control locks out. Lockout means that
The control shuts off the gas valve, spark and combustion air
Blower for 60 minutes. At the end of 60 minutes the control
Completely resets and will attempt ignition up to three times.
The control can be manually reset before the end of 60 minutes
By momentarily turning off power to the unit.
here is a link to an operations manual
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