Furnace blower won't run with Fan only setting on thermostat

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Furnace blower won't run with Fan only setting on thermostat

Postby Jrossi266 » Sat Jan 26, 2013 3:16 pm

I have a Honeywell T8132C thermostat and a Ruud Achiever 90 Plus with a model 1028928b control board. The board is brand new. I want to run the fan only in order to provide circulation for a wood burning stove we have. The blower doesn't come on when the Thermostat is on FAN and the heat is off. All the wiring looks in order. Green wire goes to G on the Thermostat as well as on the board. Any ideas
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- Furnace blower won't run with Fan only setting on thermo

Postby Freon » Sat Jan 26, 2013 4:20 pm

What is the model number on the Rudd furnace? Do you have split system air conditioning in addition to heat.
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- Furnace blower won't run with Fan only setting on thermo

Postby Jrossi266 » Sat Jan 26, 2013 5:17 pm

Model UGRA 12ERAJS. And yes, ac and heat.
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- Furnace blower won't run with Fan only setting on thermo

Postby Freon » Sun Jan 27, 2013 12:04 pm

On the furnace control board you will see spade connections for the blower motor (main fan) speeds. There should be 1 for Heat and one for Cool. The other 2 motor wires should be on terminals designated as Park. Park means not connected. When you run the Fan only at the thermostat, it usually uses the Cool motor speed connection.

First, with the thermostat set to Fan ON check the AC voltage at the furnace between the G and C (common) terminals. You should see 24 volts, AC. If you don't then check that when you have the thermostat set to Heat OFF that you aren't really turning off the entire system. That information should be in the installation manual.

If you do have 24 volts AC between W and Common, then you'll need to CAREFULLY remove the motor wire connected to the Cool spade connector on the control board. Using the meter, measure the AC voltage between that Cool space lug and the bare metal furnace frame. You should see 120 volts AC.
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- Furnace blower won't run with Fan only setting on thermo

Postby Jrossi266 » Mon Jan 28, 2013 11:33 am

Thanks...will give it a shot
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- Furnace blower won't run with Fan only setting on thermo

Postby Jrossi266 » Sat Feb 02, 2013 6:21 pm

Just a follow up. I haven't checked the voltage yet, but there is nothing connected to the FAN spade. Should that be?
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- Furnace blower won't run with Fan only setting on thermo

Postby Freon » Sat Feb 02, 2013 11:04 pm

Who is the manufacturer of the model 1028928b control board. Usually when the Fan is set to ON it energizes the motor speed connected to the cool (AC) spade. But you may have a separate connection for Fan only use.
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- Furnace blower won't run with Fan only setting on thermo

Postby Jrossi266 » Sun Feb 03, 2013 1:28 pm

I believe it's manufactured by Rheem. Part 62 24140 04
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- Furnace blower won't run with Fan only setting on thermo

Postby Freon » Sun Feb 03, 2013 3:19 pm

It appears there is a Fan spade connection available on the control board. Blower motor wires coming from the blower motor are thicker and usually colored blue, red, black and maybe yellow depending on the motor. You will see these blower motor wires connected to the Cool, Heat and Park spade connections on the control board. If there is no Park spade terminal the unused blower motor wires may be taped with electric tape. Turn off the power and move one of the blower motor wires FROM the "Park" spade terminal TO the Fan spade terminal. DO NOT MOVE THE MOTOR LEAD CONNECTED TO THE COMMON SPADE TERMINAL. The common motor lead is usually white.
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- Furnace blower won't run with Fan only setting on thermo

Postby Jrossi266 » Sun Feb 03, 2013 4:19 pm

When you say commonm you mean neutral correct.

From the blower, there is a yellow and blue wire connected to M1 and M2 spades. Would those spades be where they're Parked.
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