Lennox G27M Fan Will Not Stay On. - HVAC - DIY Chatroom Home Improvement Forum

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Old 07-17-2011, 01:51 PM   #1
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Lennox G27M fan will not stay on.

A couple of weeks ago, I noticed a pulsating sound coming from my vents. What I found is that with the AC on or FAN on, the fan is not staying on consistently.

The fan will shut off, I hear clicking in what I am guessing to be a relay, and the diag lights switch from a simultaneous blink to a solid green. After a second or two, the fan tries to restart, the diag lights switch back to a simultaneous blink. Sometimes it stays on for a few minutes, other times it will try 4 or 5 times to restart. Sometimes it will restart and keep operating as normal.

If I turn off the electricity to the furnace and then turn it on again, it will run normally for about 5 minutes. It does seem that the longer I leave the unit off, the longer it will run.

I replaced the air filter about a week ago in hopes of helping the situation, but it has not.

So I am looking for thoughts on what I should check next and how to check it. Any help would be appreciated!


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Old 07-17-2011, 02:26 PM   #2
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solid green means control board failure. sounds like the board is malfunctioning/dying. may want to get an experienced Lennox tech to check it. may have bad grounding. the replacement board is usually/probably a retrofit and difficult for the average tech to rewire and beyond most DIYers.


"Cut it twice and it is still too short".
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blower fan stops , clicking , help please , lennox , relay

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