# capacitor start motor connections



## 12bolts (Apr 27, 2014)

I have got a hermetically sealed compressor motor from an old aircon unit.
There are 3 connections going into the housing.
1 marked with the letter U and a smaller (B) in brackets
1 marked with the letter V and a smaller (J) in brackets
1 marked with the letter W and a smaller (R) in brackets
and the earth is on a stud welded to the case. I have the capacitor for the motor
What wires do I connect to which terminal?

Cheers Phil


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## BlueChipper (Apr 27, 2014)

12bolts said:


> I have got a hermetically sealed compressor motor from an old aircon unit.
> There are 3 connections going into the housing.
> 1 marked with the letter U and a smaller (B) in brackets
> 1 marked with the letter V and a smaller (J) in brackets
> ...


I found this discussion and thought it might be of help,  wife is calling so I can't dig deeper right now, hope this really helps...

http://www.practicalmachinist.com/vb/general/need-help-wiring-lathe-motor-europe-207417/


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## amuller (Apr 27, 2014)

I'm not familiar with that marking style.  In the US, hermetic compressors usually have three terminals marked (C)=common, (R)=run, and (S)=start.  Common is connected to one side of the line, Run is connected to the other side, and Start is connected to the same other side through a run capacitor.  The start winding usually has higher resistance than the run winding.  You might find this helpful:  http://www.furnaceman.com/techtips/c-s-r.htm

QUOTE=12bolts;198453]I have got a hermetically sealed compressor motor from an old aircon unit.
There are 3 connections going into the housing.
1 marked with the letter U and a smaller (B) in brackets
1 marked with the letter V and a smaller (J) in brackets
1 marked with the letter W and a smaller (R) in brackets
and the earth is on a stud welded to the case. I have the capacitor for the motor
What wires do I connect to which terminal?

Cheers Phil[/QUOTE]


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## tractorman44 (Apr 30, 2014)

The a/c compressor has a PSC (permanent split capacitor) motor in it.  Most manufacturers' terminals are read left to right like a page in a book.  Common, Start then Run.  It doesn't matter if there is a single terminal on top or if there are two terminals on top....read left to right as Comon, Start then Run.  

To make sure, if you have a DVOM, read all combinations of the ohm readings between the terminals.  When you find the two that have the highest reading.....the remaining one is the Common terminal.  Once you find the Common terminal, read between Common and the other two.  The one with the highest reading will be the Start terminal.  The one with the lower reading will be the Run terminal.

Your run capacitor in permanently installed between Start and Run where it stays in the circuit continuously. Voltage is then applied across Common and Run. 

Really simple if you look at the start and run as being in series from one end to the other attached in the middle to the Common terminal.  Confused???  If I wasn't in a rush, maybe a little better explanation could be thought up, but this will have to do for now....


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