I have a problem with a m city multi out door unit. I got error 4250 with is a inverter problem.

I tried to run the compressor from an adjacent unit by swapping over the compressor tails. but the compressor wouldn't run. So I suspect the compressor may be knackered. Checked windings - no faults to earth and continuity seems ok..

Output from inverter to netural is around 250v on all 3 legs.

When I spoke to M they advised to change comp & inverter pack!! but inverter pack is £2500.

Any advice how I can test I pack. and will fitting a new compressor to faullty inverter pack damage the compressor?
Any help much appreciated