Lennox Elite Gas Furnace Won't Light

Old 03-30-03, 06:20 PM
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Lennox Elite Gas Furnace Won't Light

I have a Lennox Elite Gas Furnace that won't light. The Vent blower comes on but the furnace only lights if you turn the Thermostat on and off (but not always). Flipping the ON/OFF switch on the furnace also seems to work at times. Sometimes the unit works on its own but no pattern seems to exists.

The furnace is about 7 years old and a Module was replaced early spring about 3 years ago while under warranty. We still seemed to have trouble with it the following winter so I am not sure that it really was fixed.

Any suggestions for a low-buck repair or diagnosis? I do have a volt/ohm meter.
Old 03-30-03, 10:19 PM
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Turning off the thermostat switch is resets the ignition control after it locks out from a failed ignition sequence. There can be many different causes to this.

Make sure your filter is clean (if you have one) as low air flow can make a high temperature limit switch open which in turn will shut off the gas flow from the valve and cause the unit to attempt to relight.

You could have a dirty flame sensor which makes for a weak current to the ignition control causing it to try and relight, then lockout. Find the sensor and clean it off with a very light sanding.

Check all the connections to the gas valve and ignitor. Make sure the ignitor has a good ground to the furnace chassis.

Make sure the heat anticipator (it's behind the cover on your thermostat) is pointing to a minimum of .6 on the scale. If not, move it there since most electronic ignitions systems require that setting to operate properly.

You can see if there is a LED light on the ignition control which blinks a fault code to help narrow down the area of the problem (some do, some don't) If there is, count the number of blinks before you turn of the thermostat or power. Then look on the wiring diagram or owner's manual for a fault code listing that equals the blinks.

You can also use your meter to check each of the limit/safety switches to make sure none of them are open after the furnace runs.

If none of these suggestions help, you should call a reputable repair service in your area.

Let us know what happens
Old 04-03-03, 06:25 PM
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Orange Module Wire

I read another thread that mentioned a similiar problem. He wiggled the Orange wire that leads to the igniter and the furnace lights. I tried it and it works. Is that wire connected in a way that it can be tightened. I thought it better to ask first before creating a new problem. Maybe this is a common problem that others have found a fix for by now.

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