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wiring question

I had a condensor with a shorted compressor today that a co-worker had replaced the fan motor 3 weeks ago. While checking it I noticed he had mis-wired it but it ran for 3 weeks! There was a potential relay, start capacitor, dual capacitor, and a contactor. He had the capacitor wire from the fan on the "fan" terminal of the dual cap but he had switched the "common" wire and the "herm" wires. The wire that goes to the potential relay and the wire that goes to the compressor were on the "common" terminal. The wire that goes to the contactor was on "herm".

How did this work for 3 weeks?

Do you think it contributed to the compressor failure?"


  • Eugene Silberstein_2Eugene Silberstein_2 Member Posts: 349
    Just a little more information...

    I am drawing this up and have three wires that are hanging around doing nothing. Are the run terminal wires on the compressor and condenser fan motor wired correctly (connected to the Common terminal on the dual capacitor)? Also, is the start capacitor wired correctly (One side connected to the #1 terminal and the other to the C terminal on the dual capacitor)?

    If such is the case, your start capacitor is not in the active circuit, as it is jumped out. In addition, the run capacitor is wired in series with the entire motor, not just the start winding.

    If the three wires I mentioned before are all wired incorrectly as well (placed on the herm terminal instead of the common), the compressor will operate normally, but the condenser fan motor will be operating with smaller than desired run capacitor, as the fan and herm capacitors will be in series with each other.

    in either case, you have the problem of a series capacitor connection, which, as you have witnessed first hand, is not a very good thing.
  • Empire_2Empire_2 Member Posts: 2,343
    Gene, did you Boot me out?

    I was trying to explain this wiring and BAM,,,,,,  I was out of the pool........:-)

    Just wondering if it was you or something on my end...

    Mike T.
  • ray hickethierray hickethier Member Posts: 26

    My co-worker only replaced the fan motor and dual cap. I have to assume he did not touch any other wires. The only thing I saw mis-wired was the reversal of the "common" terminal wiring and the "herm" terminal wiring as stated above. Unfortunately I did not see how it ran after he left. It did run through some of the hottest weather we've had this summer (100+). Ray
  • Empire_2Empire_2 Member Posts: 2,343
    edited July 2011
    A learning experience....

    Yes the system started and ran great, but in affect, the start winding of the compressor was burned out!..  The run cap has 1 job and 1 job only to for a brief second, assist the start winding to crank the compressor over.  Once it starts and runs, no assistance required.  The caps essentially charged upon call than plays a minor roll for operation.  Since the leads were reversed,  the problem is that the start winding is CONSTANTLY engaged.  Surprised that it lasted as long as it did.  Chuck it up to "Seen that, now I know".......:-)  Remember the run cap only stores electrical energy.  Basically it kicks the start winding in then ........out of the circuit.

    Hope this helped.

    Mike T.

    One thought:  Remember how when troubleshooting , say condenser fan motor?  Will not start by itself, but if I give it a twirl,,...................Runs great.................?  Ring a bell?
  • ray hickethierray hickethier Member Posts: 26

    Thanks for the answers! I will address this with my co-workers. Hopefully it doesn't happen again. I so appreciate your answers!    Ray
  • ray hickethierray hickethier Member Posts: 26

    Thanks for the answers! I will address this with my co-workers. Hopefully it doesn't happen again. I so appreciate your answers!    Ray
This discussion has been closed.


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