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I've had my house for nearly two years, and suddenly my in-wall air conditioner stopped working. I replaced the main power board, and it worked again...for a week. I replaced the main power board again again thinking maybe I'd gotten a dud but the new board lasted less than a day.

What could be causing these repeated failures and what can I do about it? Nothing should have changed from last summer to this summer in my wiring.

If it matters, it is a Kenmore model 58076129300.

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  • Have you checked the voltage coming in? Jul 2, 2015 at 15:10
  • @BradGilbert I just checked it, it seems to be normal at 118 volts Jul 6, 2015 at 18:21
  • Have you considered slapping a $100 window unit in its cage?
    – Mazura
    Jul 6, 2015 at 23:09
  • @mazura it will need a lot more than a $100 window unit, the current AC is 12,000 BTU and just barely enough to keep my room cool. Jul 7, 2015 at 18:17

2 Answers 2

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+100

I have not worked on this particular unit, but here is an educated guess:

I notice from the parts diagram that this unit is equipped with a 5KV DC power supply (Sears Kenmore part 6609A10003Q). If that has failed in such a way that it kicks high voltage back to the main power board, then that could cause repeated failures of the main board. I notice too that there is not that much that can fail on the main power board, so it is likely either a malfunction of the high voltage supply or the other possibility would be that the main compressor contact on the main power board is underdesigned and the run capacitor for the compressor is weak (Sears Kenmore part 0CZZA20001N), causing frequent locked rotor starts of the compressor and rapid failure of the compressor contact. It is much less likely that the compressor is hard starting for some other reason and if that is the case then the unit would not be economically repairable. Check the value of the capacitor with a capacitance meter. If the capacitor is less than 90% of the labeled value, then it must be replaced.

To narrow this down any further would require some on-site trouble shooting as Michael Karas stated. I am not usually a fan of the "parts-changer" approach to repair, but since the whole set of parts (capacitor, main power board, and high voltage supply) would be roughly $180 based on what I see on the internet, you may opt to replace all these parts together to save time and frustration. Also, the "searspartsdirect.com" website has information that shows how often the site sells each of these parts. They commonly sell the capacitor, main power board, and much less frequently the high voltage supply.

Good luck with your repair whatever you decide.

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  • If you go to searspartsdirect and almost place an order, then stop (but get far enough thay have your email) they may send you a 15% off offer (I went there, found the parts at a better deal elsewhere, bought elsewhere, and got a discount offer the next day...I think elsewhere was till cheaper including shipping, though.
    – Ecnerwal
    Jul 13, 2015 at 0:48
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There is a distinct possibility that another another component of the AC unit has some how gone bad and is overloading or injecting bad signals back into the control board and in turn burning it out.

It would take local diagnosis - along with a service schematic of the unit - to be able to isolate the faulty component. But your repeated replacement of the control board pretty much indicates that some other thing as gone wrong with the AC unit.

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  • There doesn't seem to be much between the power cord and the main power board. Could another component that is receiving power from the board be causing the problem? Jul 2, 2015 at 18:00
  • @JordanBentley Agreed, any one of these Sears parts may be bad. What's 5-B ? Retforrepr?
    – Mazura
    Jul 6, 2015 at 23:04
  • I blew the main board on my electric oven, it ended up being a shorted push-button on the control panel. Jul 10, 2015 at 19:45

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