Why is my mr slim a/c tripping the main C.B. on start-up, but not every time.

Try vacuuming the drain line.

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Check the disconnect at the outside unit, little box on the wall. If not, turn power off and remove top to outdoor unit.

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30 minuts working after broker trip 3 phases

Hi,
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Mitsubishi Air Conditioner Troubleshooting and Repair
http://www.fixya.com/support/r5643983-mitsubishi_air_conditioner

heatman101

continuous flash is frost prevention ...clean the filter & switch fan to high

flashes once every 2 sec could be room air sensor contact loose/short...call dealer

flashes 2x every 2 sec is indoor coil sensor contact loose/short...call dealer

flashes 3x / 2sec sensor contact problem, or compressor overload protection trip or gas leak...call dealer

Your house wiring in not capable of powering the unit. Try a different location to plug in. Check the unit to make sure it is not faulty and will trip breakers because it is damaged.

some of those units are equipped with a condensat pump you could have a loose connection or a small crack in the line

Sounds like you're on the right track. Might as well replace the , inexpensive, gfi while doing so. With power off make sure all connections are tight. Electrical tape is a wonderful thing. Good luck!!

If you need further help, reach me via phone at https://www.6ya.com/expert/thomas_092728000e6acb79

Try calling G A Larson's for technical advice. I think that they handle this product. 499-0866

41 amps is most likely a locked rotor in the compresser check on the tag of the compresser lok for LRA = Locked rotor amps) see what that reading says that is the first place to look also is it tripping the breaker or fused disconnect?