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edwardh1

SQ D Contactor failure

6 posts in this topic

This square D 40 amp (200 amp LRA rated) contactor , mexican made in a 30 running amp amp air conditioner load failed after 2 years.

The service company put in a Siemens to replace it, said SQ D were "cheap" . The heating started in the lower right and the plactic bulged out and melted on the right side. Anyone else had similar problems?

post-27-12904509402_thumb.jpg

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Need appliance parts? Call 877-803-7957 now!

I go through at least 20 contactors a season and I don't even do a lot of HVAC. It's clearly a part designed to make work for us.

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  Basically there are 2 standards of contactors / starters:

 NEMA ( National Electrical Manufacturers  Association ), and IEC ( Intertechnical European Commision ), or something like that. The NEMA standard is generally heavier duty than the IEC. They are rated for more cycles off / on, and the contacts are also heavier. The advantage of the IEC, is size. If you are in a tight spot, then this may suit you better. I have used them on several occasions, but generally dont max them out, on the FLA ( Full Load Amps ). Go to the next bigger size, just to be on the safe side. I would think the Square D would be NEMA.....but then again, maybe not. I know Cutler Hammer has both to choose from, so possibly Square D has both as well. It should say on the contactor whether it is NEMA or IEC rated.

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I wonder if it got wet during the cooling season.

 

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not wet

in a heat pump and is in service all year- also very well protected in the Rheem heat pump

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obviously the heat damage is the visual evidence of current draw.

How old is your machine (perhaps the compressor and or outdoor fan motor is having a harder time starting up due to wear and tear or capacitors outside of spec).

Since it is a heat pump, are the coils clean (dirty coils causing higher pressures in the cooling mode causing a greater load on  the compressor).

What is the mega ohm reading on your windings (are the windings breaking down causing minor winding to winding shorts or excessive heating in the windings).

What is the wire gauge serving the disconnect and the contactor and what is the length (would not be the first time that too small a gauge was used - especially on a previous change out).

Check and make sure that the disconnect is fused withing the OEM max rating (I find disconnects with fuses that are in excess of OEM specs all of the time.  This will allow the unit to draw too much current and not blow thereby hiding a true problem that needs attention but shows up as a symptom elsewhere in the system).

Just some things to consider in an effort to get you an answer other than "It is a cheap piece of crap contactor."  Look hard enough and you will most likely find your answer

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