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View Full Version : My Lennox G40UH (X) Does Not Have Hot Air => 1st LED Flashes, 2nd LED Is On


AtlantaFolk
Nov 2, 2012, 01:39 PM
Hello All Brothers, we really, really need your help. Our family live without heater almost a week. We both lost our jobs that is why we must wait until today.

Here is the problem: Based on the diagnostic codes, 1st LED flashes, 2nd LED is On => Primary or secondary limit switches open.

Here is what we did: We first took out the primary switch and bypassed it by connecting 2 wires together, then turned on the furnace. Nothing happened, it just blowed out cold air for 6 minutes.

Then, we installed back the primary switch to its place; turned on the furnace and then taped on the fiber board many times [hopefully, it would close] but nothing happened. We then bypassed two secondary limit switches by connected the wires, but nothing happened either. We also took out the plastic hose between Combustion Air Inducer & Combustion Air Pressure Switch to cleaned it up.

Currently, we put back the first and the secondary witches and the hose to their places. Turned the Gas Valve off and then on. Again, our furnace just had only cold air for a couple minutes, then it was off automatically. We also notice that the Air Inducer did not run at all.

Brothers, would you please help us out. Your input and your suggestions are always appreciated and remembered. Gods Bless you and your family, Brothers.

T-Top
Nov 2, 2012, 05:50 PM
You need to check and see if you have 115v going to the inducer motor. You can turn the power off and the back on going to the furnace to reset the control board. Check out pages 32,33,34.
Www.lennox.com/pdfs/installation... /Lennox_G40UH_IOM.pdf

AtlantaFolk
Nov 3, 2012, 06:03 AM
Hello Brother!! Would you please tell us how to check and verify if the inducer motor has 115v, and how we can reset the control board? Many thanks for your time and your help, Brothers.

AtlantaFolk
Nov 3, 2012, 09:44 AM
There is no 115V. Coming to Inducer, I tested inducer itself it running normally. How can I reset the control board? How can I get power for inducer? Do you think my control board is bad?

First, when I turned on the power, blower ran normally, but the inducer just started and stopped immediately. Currently, LED 1 still flashes, LED2 is still on. Thank you so much for your time and help.

Take care,
Tiffany