Blower Not Running


Old 05-24-15, 07:06 PM
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Blower Not Running

I have a problem with the central heating / cooling system in my house. The blower will not run. The cooling system and blower worked fine last week. I turned the thermostat off when I went on vacation for 3 days. Upon returning, and moving the thermostat back to the cool setting, the problem occurred. I can hear the AC condenser running, and the lines going into the ductwork get cold. The furnace blower does not turn on however.

Furnace unit is a Bryant heating & Cooling Systems, model 350MAV048080ADKA

Control board HK42FZ011

I read around this forum a little, and found some similar problems and things to test. This is my first time working on a furnace. Iím not afraid of the job, just inexperienced.

Things I have tested:

1. Checked run capacitor with digital multimeter. 10uF cap tested at 9.55uF
2. Checked voltage between R and Com at the furnace. ~27V
3, Turned thermostat to cool, and set fan on auto. Tested voltage between R and G at the furnace. ~27V
4. Removed black wire from L1 terminal, and black wire from COOL terminal on the control board, and connected together. Closed furnace door switch. The blower motor comes on.
Obviously the blower motor works.

Iím guessing the control board needs to be replaced. Maybe a relay went bad on the board? Can someone confirm my thinking before I drop some cash on a new control board?

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Old 05-24-15, 08:03 PM
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Welcome to the forums.

Unfortunately it does appear to be a defective control board. It may just be a defective blower relay but it will be soldered to the board and is not considered a replaceable part.
Old 05-25-15, 04:52 AM
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You may want to jump out the door switch just to be sure it is not the problem,it could be loose and not making a good connection when the door is closed.
Worth a shot.

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