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Rick Mather
Rick Mather, HVAC Technician
Category: HVAC
Satisfied Customers: 3634
Experience:  35 years experience, HVAC
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Furnace goes through all of startup sequence, main burner lights

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Furnace goes through all of startup sequence, main burner lights off but fan does not start. Fan limit switch clicks but no power going to fan eventually high limit trips. When furnace fan is in manual mode (continuous) all works fine. Not sure if it is the fan relay or a board problem.

Lennox g20Q5/6E-150-5
Sounds like the low speed tap on blower motor is bad or the fan board is bad either way you need voltage meter to confirm this
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Customer: replied 7 years ago.
Can you walk me through the process?
Check blower motor leads for power if they have power fan board will be ok and motor lost low speed tap
Rick Mather and other HVAC Specialists are ready to help you
Please don't keep hitting accept button they charge you every time you do
Customer: replied 7 years ago.
can I test this by moving the motor speed connection to medium speed terminal
Yes you could move low speed off and switch with medium
Customer: replied 7 years ago.
Thank you I'll try that
Hope it works for you