Mitsi 4250

[Pugwash]

Hi, just had a r407c mitsi r2 with fault code 4250. Found problem, comp was grounded. Anyhow out of curiosity when flicking thru the manual it turns out you can then get several 2 digit detailed codes off this error as further help. Where do you get the two digit code from, is it sw1 ? Also is it the same for 410 and 407c??

[Thermatech]

4250 is overcurrent on on compressor
4255 is overcurrent on fan motor
So the last digit of the fault code defines if the problem is with comp or fan at outdoor unit.
Before the unit stops on this fault it will have stopped on a number of preliminarry faults which were not displayed at the local remote controllers or the central G50.
To go any deeper than this you would need to be Mirsubishi employed engineer with latest Mnet monitor tool laptop.

But

If the fault was 4250 then there are 3 possible faults.
1/ the comp motor windings are down to ground.
2/ the comp is locked ( mechanical failure)
3/ problem with the IPM or inverter circuit.

1st megga the comp windings ( fare play to you as you did this & found the problem )
2nd run the system with comp disconnected from the inverter & measure the 3 ph supply from the inverter for ballanced supply.
If megga test of comp windings ok & ballanced supply from inverter then you have to conclude that the compressor has mechanical problem which is causing overcurrent.

You need to do this test because the compressor ground problem can cause damage to the inverter circuit. So you need to test it to confirm ballance compressor supply output from the inverter.
Otherwise you could replace the compressor only to find that it still wont run & then need to replace the inverter or some components in the inverter circuit.
In this case you can loose face with the customer.
So always make sure the inverter works ok when you find ground fault or locked compressor.

Try not to get hung up on the error detail codes because you need to confirm the above to be sure of the cause of the problem anyway.

I have a 3ph industrial inverter which can be connected to a 3ph power supply & used to independantly run the compressor as stand alone. Then if it still trips on overcurrent at start up with the industrial inverter then the comp is definately locked.
Catch is the industrial inverter costs best part of 2k.

[Pugwash]

yes narkom, thats what i had seen and was curious if that code can be read off the r/c or is only available to mitsi eng or someone running the mnet tool as thermatek responded.. not sure what other fault codes produce these further two digits, think its just codes 4000 thru 5000?

[kkeithd2]

I guess the question was about an "Error detail code" [101], [104], [105], [106], [107] (see attachment). Would you please explain how to get this digits?

use SW1 to get inverter error history this will give detail code.