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 Repairing and Servicing Lennox Products
 Repairing / Servicing Lennox Gas Furnaces
 Lennox G24M3/4-100A-2 stranger problem
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hg863

5 Posts

Posted - 12/01/2008 :  11:58:18 PM  Show Profile  Reply with Quote
My gas furnace is a Lennox G24M3/4-100A-2 and the installation instruction shows the year is 1995.When I turn on the thermostat the blower will come on, but after a while the gas valve will click continually to do open and close.I test the valve's voltage it is changing rapidly. This problem only happened in cold weather.I tried a method to temporarily solve this issue. I use a fan heater heats the gas valve aera about 30 seconds,then I turn on it will work fine. Last week was very cold here, so I had to keep heating the gas valve whenever the furnace started, otherwise the gas valve would be clicking.I changed the gas valve, but the problem still remains. I also changed the Primary limit control switch, Pressure switch, Flame sensor, Direct spark ignitor and two Flame rollout switchs.They all are not helping. I am exhausted. Please help me. Ron He

Cozy.Support

5779 Posts

Posted - 12/02/2008 :  10:57:44 AM  Show Profile  Reply with Quote
This is an unusual symptom. You have changed so many parts already, it seem that you would have to be suspicious of the control board. However, I realize that one would not think the control board was the issue since the furnace would work fine when you heated the gas valve. Even if you have limits that open during a heat cycle, they should not be going off and on that fast.

Just to be on the safe side, you might want to jumper the vent pressure switch while it is acting up so that you can rule it out, but the symptoms really do not point to the vent safety switch. You have done everything else so you just as well rule out the vent safety switch as well.



Cozy.Support does not provide a diagnosis for users of this forum. We do, however, try to provide information that will help servicers arrive at their own diagnosis.

Once you know what part you need, you can contact the Cozy parts department by using the link below
http://www.cozyparts.com/Lennox-Parts/locator_form.aspx

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MechAcc

1499 Posts

Posted - 12/02/2008 :  5:42:55 PM  Show Profile  Reply with Quote
What is the voltage to the gas valve?

I am not an employee of CozyParts. The opinions that I post are my own.

Please have your furnace inspected annually by a qualified service technician. Have all of your fossil fuel appliances tested annually for carbon monoxide production by a professional.

Get a good Carbon Monoxide Alarm. Replace it according to manufacturers recommendations usually every 3-5 years. CO concerns are not just for the winter but 24-7. UL approved alarms alarm high. For a low level alarm do a search for CO Experts or NSI 3000 a low level CO monitor.
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shoe

141 Posts

Posted - 12/02/2008 :  10:16:33 PM  Show Profile  Reply with Quote
I love situations like this - ever since I started cutting my hair so short that it can no longer be pulled out by the clumpful ( when I find myself in situations like this ).

It would be helpful to eliminate the possibility of something outside the furnace causing the problem. Jumper 'R' to 'W' at the terminal strip for the thermostat wires. Does it work okay in this condition? If yes, the problem is with the thermostat or t-stat wiring.

Also, make sure no ground ( green ) wires have been cut or left disconnected.

-------------------------------------------

I am not affiliated with Cozy Parts or Lennox in any way.

The opinions I provide are my own. You have no idea whether or not I'm qualified to hold them. Use them at your own risk.
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hg863

5 Posts

Posted - 12/02/2008 :  10:56:44 PM  Show Profile  Reply with Quote
I will try your way later, because recently the weather is warmer,and the furnace is working fine.I like to try any possibilitiy. Thank you here. I will tell you after I try it. Ron He

quote:
Originally posted by shoe

I love situations like this - ever since I started cutting my hair so short that it can no longer be pulled out by the clumpful ( when I find myself in situations like this ).

It would be helpful to eliminate the possibility of something outside the furnace causing the problem. Jumper 'R' to 'W' at the terminal strip for the thermostat wires. Does it work okay in this condition? If yes, the problem is with the thermostat or t-stat wiring.

Also, make sure no ground ( green ) wires have been cut or left disconnected.

-------------------------------------------

I am not affiliated with Cozy Parts or Lennox in any way.

The opinions I provide are my own. You have no idea whether or not I'm qualified to hold them. Use them at your own risk.

Go to Top of Page

hg863

5 Posts

Posted - 12/02/2008 :  11:06:57 PM  Show Profile  Reply with Quote
The voltage is 24V in woring situation. I will do a reserch about what you have mentioned. Thank you very much. Ron He

quote:
Originally posted by MechAcc

What is the voltage to the gas valve?

I am not an employee of CozyParts. The opinions that I post are my own.

Please have your furnace inspected annually by a qualified service technician. Have all of your fossil fuel appliances tested annually for carbon monoxide production by a professional.

Get a good Carbon Monoxide Alarm. Replace it according to manufacturers recommendations usually every 3-5 years. CO concerns are not just for the winter but 24-7. UL approved alarms alarm high. For a low level alarm do a search for CO Experts or NSI 3000 a low level CO monitor.

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hg863

5 Posts

Posted - 12/02/2008 :  11:14:11 PM  Show Profile  Reply with Quote
Is the vent pressure switch the secondary limit control switch? I cannot find the vent pressure in my instruction. Ron He

quote:
Originally posted by Cozy.Support

This is an unusual symptom. You have changed so many parts already, it seem that you would have to be suspicious of the control board. However, I realize that one would not think the control board was the issue since the furnace would work fine when you heated the gas valve. Even if you have limits that open during a heat cycle, they should not be going off and on that fast.

Just to be on the safe side, you might want to jumper the vent pressure switch while it is acting up so that you can rule it out, but the symptoms really do not point to the vent safety switch. You have done everything else so you just as well rule out the vent safety switch as well.



Cozy.Support does not provide a diagnosis for users of this forum. We do, however, try to provide information that will help servicers arrive at their own diagnosis.

Once you know what part you need, you can contact the Cozy parts department by using the link below
http://www.cozyparts.com/Lennox-Parts/locator_form.aspx



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hg863

5 Posts

Posted - 12/07/2008 :  2:15:19 PM  Show Profile  Reply with Quote
Hi, I jumpered 'R' to 'W' to turn on the furnace, but the problem remained, and I still need to heat it to make it work.The grounding wires also are good. I am thinking it maybe caused by ignition or flames sensor cables. If I pull one of those cables off, it will make the gas valve clicking when I turn on thermostat.Do you think there are any possibility here? Ron He

quote:
Originally posted by shoe

I love situations like this - ever since I started cutting my hair so short that it can no longer be pulled out by the clumpful ( when I find myself in situations like this ).

It would be helpful to eliminate the possibility of something outside the furnace causing the problem. Jumper 'R' to 'W' at the terminal strip for the thermostat wires. Does it work okay in this condition? If yes, the problem is with the thermostat or t-stat wiring.

Also, make sure no ground ( green ) wires have been cut or left disconnected.

-------------------------------------------

I am not affiliated with Cozy Parts or Lennox in any way.

The opinions I provide are my own. You have no idea whether or not I'm qualified to hold them. Use them at your own risk.

Go to Top of Page
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