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HVAC Forums => HVAC Help => Topic started by: brodie123 on May 24, 2013, 06:31:18 PM

Title: AC motor wiring help needed
Post by: brodie123 on May 24, 2013, 06:31:18 PM
Hi All;

We are trying to install a new furnace fan motor. The new unit is a marathon electric CAT NO B208.

115V single phase AC motor

There is a wiring diagram, but seems incomplete. I've search their site for wiring an cannot find any.

The wiring refers to red and black only, and shows you which post to put them on for CW or CCW. (we want CCW - so we reverse them as per the diagram).

It also refers to "ungrounded line" which I assumed to be the AC supply however under no-load, the motor kept turning on and off whith a "click" I assume to be the thermal protection?

Can you please indicate the rest of the wiring? I don't want to fry the motor getting it wrong.

The remaining wires are Blue and Yellow.

Thank you in advance.
Title: Re: AC motor wiring help needed
Post by: rmuntz on May 24, 2013, 09:53:08 PM
http://www.marathonelectric.com/CnxDocRequest/PublishedPDF/52a105379aa.pdf (http://www.hvactechgroup.com/files/b208.pdf)

Line wires connect to same terminals for either rotation, the red (t8) and black (j9) are switched to change rotation
Title: Re: AC motor wiring help needed
Post by: Admin on May 25, 2013, 09:57:53 AM
What are you connecting to in the furnace?  A black and white wire or control board?

I think this motor uses the yellow wire as a neutral.