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Griffinfamily6 01-01-2011 05:42 PM

Lennox G26 turns off after 30 min.
My Lennox G26 turns off after 30 min. My house was at 63 degrees when we woke up. We live in MN and it is 8 degrees outside. The thermostat is set at 70. The system states that it is on and the fan is set to "on". There is no air coming out of the registers. When I go to the furnace and flip the "On/Off" switch off and on... it starts up and produces hot air for a half-hour or so and then the furnace turns off again. I have repeated this 10 times today.
Do you have an educated guess as to what is happening? Thank you! -Bob Griffin

gregzoll 01-01-2011 06:16 PM

What is the code is the LED flashing? The manual is available at Lennox's site. You can take the bottom panel off, especially that some of the circuit boards have the LED in a place that the site glass is not able to let you see it. Keep in mind, that you will have to hold the kill switch to have the unit powered up, or jumper across the terminals on it after shutting the power off to the unit, so you can safely do so, then turning the power back on.

Griffinfamily6 01-01-2011 06:24 PM

Two green lights flashing quickly - simultaneously

yuri 01-01-2011 06:39 PM

Post the complete model #. B4 you reset the power look at those green LEDS, should be flashing an error code which should be on the inside of one of the doors. If you reset the power 1st you erase the code we need. Right now it is flashing a normal power On code. Check your air filter, make sure all vents are open and check the intake/exhaust pipes outside for blockage or snow buildup.

gregzoll 01-01-2011 07:14 PM

Left out pulling the plug for the box on the side that the drain goes into. I always drain mine about every other month during Winter, so that any moisture/water does not get to the point of causing problems, in case it does not drain out. Also, on my unit, which I know is on a lot, there is nothing on the doors for a code sheet, so the book would be the next best thing, or

yuri 01-01-2011 07:17 PM

Post your complete model #, Marty and I have secret inside access to Lennox info for the codes:detective:

Marty S. 01-01-2011 10:09 PM

Fan turned to "ON" and no air movement would have me checking if the motor is turning or not. If the answer is no then check if the circuit board is sending 120 volts to the motor or not. Eliminate possible problems in blocks-circuit board- motor-capacitor. Could be more then one issue but start with voltage and go from there.

Double fast flash is a normal call for heat. Any fault code will only happen a few times then the diagnostic lights will flash a watch guard code which means it's locked out for one hour and then will try again.

Griffinfamily6 01-01-2011 11:14 PM

Left LED is blinking and Right is Steady. My manual states that this means a Primary or Secondary Limit switch is Open. Any advice is much appreciated. Thanks! -Bob

Model number G26Q 3/4 - 100 - 5

Marty S. 01-02-2011 12:10 AM

Limit is from lack of air flow. Back to checking circuit board, motor and capacitor. Filter's clean isn't it?

Griffinfamily6 01-02-2011 12:18 AM

Thanks for your reply! Filter is clean and everything else looks visually clean. This is the first time in 10 years for this problem.

Griffinfamily6 01-02-2011 10:49 AM

Although the Filter didn't look particularily dirty, I did take it out and clean it (it is a washable filter). There was a lot of dirt that came out. After putting back in... the furnace is working normally and the house is holding steady at 70 degrees!

Thank you to the kind individuals that replied to my post. It is great to have people willing to share their wisdom! :thumbup:-Bob

yuri 01-02-2011 11:06 AM

Yep, and some modern furnaces have very low limit control settings ie 170 or 180 degF so it takes very little air restriction B4 they start cycling on the limit control.

Griffinfamily6 01-02-2011 11:44 AM

Thanks again to Yuri, Marty and Greg for responding to my posts! -Bob:thumbup:

gregzoll 01-02-2011 12:47 PM

Set a reminder on your computer & cell phone to clean the filter every 20-30 days. Also make sure that you let it dry out for most of the day before putting back in. It is not going to hurt to have it out for a day, just remember to put it back in.

14701NYtileman 01-02-2011 01:02 PM

More than likely a plugged intake or exhaust. Try looking at the PVC pipes going from the furnace to the outside make sure no obstructions. If that's fine check the flame switch.

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