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20 year old Amana 3.5 ton runs for 15 minutes and then blow circuit breaker on the main panel in the house. Condenser fans running compressor is running sweating making cold air. Help.

EDIT

Two 40amp breakers toggled together one of them gets hot when it pops that breaker automatically pops the one that's connected to. This unit has run flawlessly for 20 years. It's a Square D panel with Square D breakers

I believe 22amp ZRCF42U01D MOD#

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    What size is the breaker, what size are the wires feeding the air conditioner, what's the nameplate (branch-circuit selection) amp rating of the A/C, and what's the maximum fuse/breaker rating of the A/C? I can't read the nameplate off your air conditioner through the Internet! – ThreePhaseEel Jul 19 '18 at 1:58
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    Also, what make/model is the breaker feeding the A/C? – ThreePhaseEel Jul 19 '18 at 2:04
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    This breaker is a 2-pole 40 A breaker, the halves are not separable, and the combination is purchased and replaced as a unit. – Jim Stewart Jul 19 '18 at 9:14
  • @Eric Please register your account and then merge them so you have access to edit, comment, and accept answers on your own question. Posting multiple responses as answers can result in an automated lock that can prevent others from assisting you. – BMitch Jul 19 '18 at 17:00
  • Contact your power company and see if they have any subsidies for replacing old air conditioners. A/C units run during "peak" times, and part-time peaking units must be fired up to supply the extra load. Peakers sit idle most of the time, which makes them so expensive-per-hour that it's often cheaper for power companies to help you buy efficient appliances than buy more peakers. A/C units are the biggest peaking load, so they are the top priority for efficiency. – Harper - Reinstate Monica Jul 19 '18 at 18:12
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The breaker may be faulty or there may be a fault in the a/c condensing unit. Breakers are so cheap and easy to replace that I would replace the breaker, but those more knowledgeable about a/c's may know better.

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    Ok Jim your the man!! It ending up being a bad Square D breaker !!! I would never thought that's what it would be. It's a brand new panel last summer. Thank You Thank You !! Total cost of repairs $9.57 !! – Eric Hermann Jul 19 '18 at 18:23
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I see 2 problems that cause this, the first is a start run capacitor, it may be just a run capacitor as many units use caps with 2 caps. In 1 can. The start cap gets it up to speed but the compressor starts working harder to stay at speed it draws more and more current until it trips. The second is an incorrect Freon charge. At the age of this unit it is probably low with the possibility of air have gotten in the system. You can change the cap but to have the Freon checked and topped up you will need a service call. Actualy I thought of a 3rd thing but this starts from a low Freon pressure , if moisture has entered the system it will mix with the oil and turn acidic then starts to etch the varnish off the motor wiring. A resistance test and insulation test (megger) can check to see if the windings are good. If your system has s site glass and the oil is black that is a good indication of contaminated oil. Also if the system is low there will be a lot of bubbles in the site glass or almost no liquid.

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Okay guys it was a defective Square D circuit breaker in the panel I changed that out after checking everything else above because I didn't believe that's what it could be but sure enough that was it thank you so much

  • Yeah, the overheating on one side only was kind of a clue (especially on a 240V only circuit) -- that, and it'd be weird for a breaker to trip after 15 minutes. Was this a Homeline or a QO that went bad, by the way? (Homelines are wider, lack the little window in front, have handles on all the poles, and are marked HOM on their label, while QOs are skinnier, have a little window on the front, only have one handle sticking out the front, and are marked QO on their label) – ThreePhaseEel Jul 19 '18 at 22:28

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