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tls1 08-08-2012 06:49 AM

furnace fan wiring improvement
Hi all,

Currently we have a multi speed direct drive fan in our furnace. And we have a heat pump for AC in the summer and light heating. When it's cold we use oil. The thermostat has a switch for fan auto or on. It works fine, and I believe it is wired for highest speed only for both setting.

I would like the system to work as follows:

in Auto mode when using AC: fan either off or high speed.
in Auto mode when using heat: fan either off or lower speed.

in On mode when not heating or AC: fan on lower speed.
in On mode when using AC: high speed.
in On mode when using heat: lower speed.

The reason for high speed on AC is because cold air is heavier than hot air...therefore requires more power to move it.

I'm not sure how many speeds the motor has at this time. I will investigate further.

Any other suggestions or ideas are welcome.

What would I need to buy? And a wiring diragram.
I don't mind having a manual switch to swith between summer and winter mode if necessary.

We have an Aube thermostat model TH146 (multistage) and the control module: CT280-2H1C
manual here:


Acomfort 08-08-2012 06:55 AM

if you could post some pics that would help

tls1 08-08-2012 05:19 PM

1 Attachment(s)
Here is the motor...

there is a BX cable with three wires going to the capacitor. I guess 2 for power and 1 ground. I guess I would need to replace that...

tls1 08-08-2012 05:32 PM

I removed the cover on the wiring box next to the capacitor. It was difficult to see and I did not want to disturb anything.

I guess the white is power.

The black (hi), blue (med), red (lo) are the other power.
I could not see the black, The blue was not connected to anything. The red appeared to be connected to another red wire.

It cannot be running on low... this things blows harder than well... I cannot say it ... I will be kicked out...

I will have to turn off the power later and try again.


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