I am having a problem with my heating unit. The board is GMP100-3. When I turn on the heating unit, the inducer motor starts, ignitor glows and then nothing happens. The gas will not flow in to start and ignitor turns off and whole thing stops. This repeats for 3 times and then systems shuts down. I do hear few clicks during this cycle. What can possibly be the problem? Can anyone help??
Inducer and Ignitor starts but no gas
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What is the flash code on the control board?
Once you find it find the code chart and post the results.
Is this a 80 or 90+ % furnace?
Once you find it find the code chart and post the results.
Is this a 80 or 90+ % furnace?
It gives one blink which means problem with gas flow, gas pressure, gas valve or flame sensor. I did clean flame sensor with sand papers but didn't make any difference...
I am not sure what 80 or 90+% means. Can I look up this some where?
I am not sure what 80 or 90+% means. Can I look up this some where?
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It's natural gas for sure. What is flue pipe?
I asked my friend to bring a voltage meter so I can check this. Once I have the voltage meter, what should I do with it? What should be the correct voltage? If it's not correct, then how can I fix it?
Sorry for asking so many questions and thanks for everyone's help in advance.
I asked my friend to bring a voltage meter so I can check this. Once I have the voltage meter, what should I do with it? What should be the correct voltage? If it's not correct, then how can I fix it?
Sorry for asking so many questions and thanks for everyone's help in advance.
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Bare with me..look at the gas valve and tell me how many wires are going to it and if you can the terminal lettering.
What you need to do basically is take the black lead to ground and the red lead to each of the terminals to see if voltage is getting to the valve and though the valve windings.
The voltage is approx 24-27 vac
What you need to do basically is take the black lead to ground and the red lead to each of the terminals to see if voltage is getting to the valve and though the valve windings.
The voltage is approx 24-27 vac
There are 2 wires connected to gas valve. One is purple wire hooked to slot with V and P letters on the left side and 1 and 3 numbers on the right. The other wire is blue and is hooked to slot with letter C on left and number 2 on right..
BTW, my flue pipe is metal.
BTW, my flue pipe is metal.
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Ok
Take the black lead and go to ground..Anything metal on the furnace
Take the red lead and go to the V terminal. Set the meter to AC voltage so that it will read 0-100
Have your buddy turn up the stat and make a call for heat.
On the first try for ignition measure the V terminal - Purple wire
On the second try for ignition measure the C terminal - Blue wire
Post results
If you have power on both terminals then you have a bad gas valve
If you have power on the purple wire but not on the blue wire. Then you will want to remove both wires and measure in ohms between the two terminals for continuity. If there is no continuity then you have a bad valve. If you have no power to the valve you may have a bad control board.
Take the black lead and go to ground..Anything metal on the furnace
Take the red lead and go to the V terminal. Set the meter to AC voltage so that it will read 0-100
Have your buddy turn up the stat and make a call for heat.
On the first try for ignition measure the V terminal - Purple wire
On the second try for ignition measure the C terminal - Blue wire
Post results
If you have power on both terminals then you have a bad gas valve
If you have power on the purple wire but not on the blue wire. Then you will want to remove both wires and measure in ohms between the two terminals for continuity. If there is no continuity then you have a bad valve. If you have no power to the valve you may have a bad control board.
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Sorry, I got typing to fast.
If you have voltage in and out of the valve then you need to check gas pressure to the valve before replacing the valve.
If you have voltage in and out of the valve then you need to check gas pressure to the valve before replacing the valve.
I found the problem. The purple wire had connector on top cover of the burner. It had no voltage. However, it also had a reset button. When I pressed the reset button and check the voltage again, it worked. I turned the unit on and everything works fine.
Thanks so much for your help. It's nice to know that there are people like you who will help others.
Take care and keep up the good work!!!
Thanks so much for your help. It's nice to know that there are people like you who will help others.
Take care and keep up the good work!!!
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1,517 Posts
Was this button you pressed on a disc type devise?
This could be a roll out limit switch and may be indicating that you have another problem.
The purple wire from gas valve goes to side cover of the unit first. From there, it goes to top cover of the unit and then to the board. On top of the cover, it has a small unit with tiny rectangular button on top and 2 flat metal pieces on the side. The purple wires are connected to these 2 small flat metal pieces by sliding them into the metal, similar to way we connect USB devices to USB ports in computer.
How do I find out if there are other problems?? Is there any other tests I can do to check?
How do I find out if there are other problems?? Is there any other tests I can do to check?
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Yes, I ave only had one time in 15 yrs that the switch was bad.
The limit tripping is caused by either the limit bad or more than likely excessive heat coming out of the heat exchanger. Below are likely causes.
You could have a few things wrong
1. Gas valve over supplying gas to the burners
2. Restricted heat exchanger
3. Cracked heat exchanger
4. Bad roll out limit
At this point I would advise you to call a pro to check this out. If the gas pressure is to high then you are over heating. If you have an issue with the heat exchange you may be releasing carbon monoxide into you home.
Either way a $50 or so service call is cheaper than the out come of the above.
Hope this helps
The limit tripping is caused by either the limit bad or more than likely excessive heat coming out of the heat exchanger. Below are likely causes.
You could have a few things wrong
1. Gas valve over supplying gas to the burners
2. Restricted heat exchanger
3. Cracked heat exchanger
4. Bad roll out limit
At this point I would advise you to call a pro to check this out. If the gas pressure is to high then you are over heating. If you have an issue with the heat exchange you may be releasing carbon monoxide into you home.
Either way a $50 or so service call is cheaper than the out come of the above.
Hope this helps
Thanks for the replies once again. I have asked someone to come and check the unit. However, as he is currently out of town, he won't be able to come till next Sunday. Until then, I am not sure what I should do. The unit is working fine for past few hours now.
If it is heat exchanger problem, would my unit stop working again in the near future? I will go out tomorrow to buy a carbon monoxide detector to be safe but I am not sure if I should use my heating unit until I fix it or at least find out the issue.
If it is gas valve over supplying gas, how can I check this? I have not touched the valve ever since I moved in to this house which was 7 yrs ago. Should I turn the valve just a little to reduce the gas?
Last year, I had an issue with flame sensor. After I cleaned it with sand paper, it's been working fine. I am not sure if these issues are related...
If it is heat exchanger problem, would my unit stop working again in the near future? I will go out tomorrow to buy a carbon monoxide detector to be safe but I am not sure if I should use my heating unit until I fix it or at least find out the issue.
If it is gas valve over supplying gas, how can I check this? I have not touched the valve ever since I moved in to this house which was 7 yrs ago. Should I turn the valve just a little to reduce the gas?
Last year, I had an issue with flame sensor. After I cleaned it with sand paper, it's been working fine. I am not sure if these issues are related...
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I would get a CO monitor and run it at the lowest setting you can.
If the limit trips again I'd call your buddy and see if he can get there sooner.
Checking gas pressure requires a manometer to check pressure. I'd say Yuri hit it on the head and the heat exchanger has popped a ring.
At this point my advise to you is let a pro take a look at it.
If it is over fueling some times it sounds like a train..really loud.
If the limit trips again I'd call your buddy and see if he can get there sooner.
Checking gas pressure requires a manometer to check pressure. I'd say Yuri hit it on the head and the heat exchanger has popped a ring.
At this point my advise to you is let a pro take a look at it.
If it is over fueling some times it sounds like a train..really loud.
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