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Comfortmaker furnace fires sometimes

Cycles 2 or 3x and then valve will not open (new glow plug is installed)

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  • richglenn Jan 07, 2009

    I believe it may have been a build up of dust on the mercury switch on the T stat...but It did fail to light one time after that with a red light blinking on the module. I think it was 3 blinks. I also hear a strange click from solenoid on valve but it opens and shuts down properly (noisy though). T stat is new and glow plug.

  • richglenn Jan 08, 2009

    Cycles fine for half a dozen times and then codes to red solid light no blinking. Then you half to lower the T stat all the way down and back up to desired temp. Light goes out when you lower the Tstat and then it fires up when you raise it back up.

  • Danny Clark
    Danny Clark May 11, 2010

    Is the ignitor glowing? Any fans coming on? any ignition? what exactly is it doing/not doing and in what order?


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Is there any led lights inside the fan cabinet that blink a code if so write down the code then check inside the panel it might tell you the code description if so let me know what the description is and we can procede

Posted on Jan 06, 2009

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Sounds like a faulty board. shut the power to the furnace off for a minute then turn it back on. Make a call for heat at the thermostat. The inducer should start and close contacts on a pressure switch . Once pressure switch closes the hot surface ignitor should glow red. Then the gas valve will open when the gas valve opens you should get fire till the stat is satisfied. If your concerned it is the jump out r to w on the board this will eliminate the stat. If you to reset the rollout switchs 3 timesyou're getting flame rollout and you either have a cracked heat exchanger or blockage in the exhaust piping or a bad inducer motor. Keep me posted with what you find!

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It does not fire at all times igniter works, I can hear the gas valve when opens, some times it fires for a minute and some times does not fire at all

Problem: Your furnace will not ignite the gas to produce heat for your home. When a furnace has a bad ignitor what I see most of the time is the following sequence of operation:

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 | Heating & Cooling

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I have an amana furnace and it will not kick on. When the switch is turned on the furnace will try to run but won't warm up and blow. Does it have a pilot light?? or a reset button??

Try this----turn furnace off at stat and unplug furnace for 10 minutes. Plug it back in, the combustion and blower motor may both kick on for 2 minutes or so or not. Turn t-stat to heat and turn up stat to highest setting. Hurry out to furnace and you should hear the combustion motor(little motor piped to flue) kick on, then wait for a "click" next you should see a glow from the igniton element, then another click, next will be the gas valve opening. If no ignition, it will try 3 times and then lock ur *** out, and just turn on the blower just as a precaution. If you dont see the glow plug glowing after the first click, replace the $20 glow plug and you should be good to go. The glow plugs crack, and this is what breaks the connection. If you gas valve has a knob, and says pilot----turn the valve to pilot, push down on the knob, light the pilot and hold down knob for 2 minutes to heat up flame sensor. Make sure the t-stat is all the way down or off. After 2 minutes of holding pilot knob down, let go and your pilot should be still lit, if it is, then turn gas valve to ON and then turn t-stat up to kick on furnace. If ur pilot doesn't stay lit, get a new thermal couple and replace it-$12 bucks. Good luck and let me know how it went.

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1 Answer

Furnace glow plug lights but main burner doesn't go on

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A/C, & Heating Contractor

Sep 28, 2010 | Heating & Cooling

1 Answer


Hi, I have seen this so many times. It could be a couple of things.In the sequence of operation, normally the small inducer fan will start to come on first, if your model has one. With the motor on, it closes a set of contacts telling the module, hey I am on and running. A safety device.Module sends power to the glow plug to light. If it glows but doesn't light, it may try a couple of times before it locks out the module, and you're indoor fan will come on and run.1 of 2 components will be at fault. Either the main gas valve coil is dead and not opening to fire the burners when the glow plug is established, or the ignition module is faulty not sending 24volts to the main gas valve to open. Try this, go to the unit and have someone set it to come on. When you see the glow plug start to get hot, listen very closely to the main gas valve to make a click.You can even put your finger on the small coil and feel it energize. If it does click, and you can fill it do so, this means it is getting the 24 volts to open and fire, but the coil is faulty and you must replace the valve. If you have a volt meter, you can put you're 2 leads on the 2 terminals, hot and common to see if you have 24 volts to it when the glow plug glows and its time for the valve to open.A click, feel, or 24volts,a/c tells that the module is good but valve is faulty.If no sound, click, or no feeling anything and you do have a volt meter and you have no 24 volts there at valve when its time to fire, the module is at fault and must be replaced. You can check for 24volts ac there also at the terminals marked mgv, and c or Grd.You should have 24volts there when glow plug is glowing before it goes out.I wanted to fully explain to you the steps you must take to find the solution, I know it might sound confusing, but it is rather simple when you know the sequence of operation of something. You can purchase the valve or module at an appliance parts house. Mark all wiring and draw a picture of the part you are replaceing.The gas valve is very easy to remove and install.It could be 1/2x 1/2 pipe or 1/2x 3/4, 3/4x3/4 ect.Turn off gas. remove flex line. Remove gas hand valve. Remove pipe nipple. Grab hold of main gas valve and turn CCW while holding nipple at other end. Remove wiring first and mark.Install in reverse using pipe dope. You can do this by hearing the click without a meter. It would be helpful if you could pick up a cheap model at like Sears tools.I do this just about everyday and I can promise you it is one of the two components.Please keep me informed and make a copy of this solution if you like for reference. It should not take you to long to know which is faulty. Best of Luck, and Sincerely,

Dec 06, 2009 | Heating & Cooling

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