I have a Panasonic cu-g125ke AC unit which trips the circuit breaker 30 seconds after its's powered on. I have searched the manuals for what to do but it says: contact a dealer in your area. The problem here is that there is no authorized dealer in my area... A non-authorized one could not find a solution. So, I thought I'd take action and search for errors on the devices (indoor, outdoor) in order to replace broken parts, but don't know how to do it. Suggestions are welcome!

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  • Possibly the breaker is defective. Is this a dedicated circuit or are there other receptacles or lights on the circuit. If so remove all other loads and see if the breaker stays on. What is the size (current limit in Amps) of the breaker? Is it a 1-pole (120 V) or a 2-pole (240 V)? – Jim Stewart Jun 20 at 19:21
  • no, it's just the ac unit. the circuit breaker is 240v. – user30058 Jun 20 at 21:16
  • Is it new and doing this from the outset, or is this old and was working fine for years, then just recently started doing this? If old and recently started, was it unused all winter and just turned on for the first time this year? More details are better. – J. Raefield Jun 20 at 23:14
  • The Panasonic cu-g125ke is a mini-split, right? Don't these have a "soft-start" design in which there is a much lower peak starting current for the compressor? What do the instructions say about the size of wire and breaker? What wire and what size breaker (Amps limit) do you have? – Jim Stewart Jun 21 at 11:35
  • How old is the unit? I find on the older ones if they still have a charge the inverter has failed (this is the electronic controller for the compressor) the controller can be replaced and the cost has really dropped in the past 5 years, but this may be the problem because the electronics do a sensor check then try to start the compressor. The triac’s or SCR’s in the inverter are the component that usually fails but the entire controller usually needs to be replaced because when the Triac/SCR’s fail they usually short out first and this damages everything around them including the pc board. – Ed Beal Jun 24 at 15:03

When an air conditioner is first turned on, the compressor motor encounters high back-pressure from the warm gas, which goes down a bit while running. If nothing is broken in the AC, then perhaps there is a high initial inrush, causing the mains circuit breaker to trip. Try the following:

  • Make sure all other appliances and lamps on that circuit are off when starting the AC.
  • If the circuit breaker is less than 20 amperes, try a heavy duty extension cord (rated for more than 15 A) to an outlet on a 20 A or greater circuit.
  • If you can remove the AC from its case, see if the fans are free to rotate. Sometimes debris can block them. Lubricate bearing, if possible.

If that does not get it working, then, regrettably, mechanical problems often cost more to fix than the price of a new AC, so there is probably little point in probing further.

BTW, the manufacturer's user manual, p. 24, is less than helpful: "Is There a Problem? Call the dealer immediately."

  • Inverter based units operate much differently than old school compressor on /off units. The electronics are a prime suspect over mechanical if the unit still Has a Freon charge. I mention if it still has a Freon charge because some precharged hose sets do not get pumped to a 500um vacuum and end up leaking all the Freon out in a few years. – Ed Beal Jun 24 at 15:08

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