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· Registered
12 Posts
Discussion Starter · #1 ·
Please help i replaced control board on a lennox that i asked about the other day. Now when i turn it on it does nothing,
i label all connectors befor removal and installed new one there is one connector left on control board with nothing
on it and one connector left running close to control board
i didnt label it when i removed it and dont remember it connected it runs to the main blower to the house not the
exhaust blower. I tried connecting it to the left over connector on control board( on old control board) but nothing happens still. The left over connector on control board is labeled (hum). The other connector above it is labeled
cmb blwr which i have connected to the exhaust blower. Did
i do something wrong and how can i find out were it goes
or how to test it. When ever i disconnected the old control
board it would start exhaust blower and try to spark now
it does nothing, but green light flashes... Please help


· Hvac Pro
25,132 Posts
Here is the manual for your unit. Also there should be a wiring diagram on the back of one of the doors.
I am wondering if you now have the wrong board. HUM is for a humidifier which your package unit cannot have. Try for Lennox parts. I need you to use some periods in your writing as it is a bit hard to understand.
Your unit is older and sometimes Lennox has retrofit boards made by a different company and you need to carefully follow the instructions with the new board. Hopefully the one you bought is not damaged. They need the complete model and serial# to find the correct part.
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