Indoor Blower does not turn on - need new control board?


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Old 12-04-13, 05:11 PM
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Indoor Blower does not turn on - need new control board?

Hello all,

So I have a Lennox 80MGF3-75A-1.

When i turn the heater on:
- the combustion blower turned on
- then after couple second, fire is ignited and burner is on
- after that the main blower (indoor blower) does not turn on
- then after 1 minute or so, the burner died (i think due to overheating).

In the control board, the LED then flashes 4 times.
Based on the manual, it says something about Primary Limit, Rollout
Switches and Secondary Limits, but I ask an heating guy, he said it is a bad board. We did try to by pass the board and the blower works just fine.

Do I need a new control board or is there anyway to fix this and not replacing the control board since it costs me ~$500+installation for replacing the control board,

Thanks in advance guys.
 
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Old 12-04-13, 06:46 PM
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shop around for the board

repairing boards is not a factory authorized repair generally...maybe a relay failure on the board?
 
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Old 12-04-13, 07:56 PM
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Welcome to the forums.

As boilernut mentioned it's most likely a relay problem and that is usually true.
Unfortunately they don't sell them separately.
 
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Old 12-06-13, 12:14 AM
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So the heating guy finally replaced the control board with 19W94 Lennox (he charges $500 for $300 board and $100 installation, but since I am too busy and need it replaced soon, I pay it anyway). Now another problem arises.

My furnace is located in a room inside my garage along with hot water tank. With the new control board and the door closed in the room, if I turn on the furnace, after 10-15 minutes, the furnace shuts off and with the 2 LED , red is flashing and green is on - diagnostic says either primary or sec limit switch has opened.

However, if I leave the door open (I guess it is cooler because air from outside the room is going in), the furnace works just fine.

This never happens with the old board. Anyone can help with this issues?
 
 

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