mitsubishi mr slim

[derekbradbury]

Hi all,

This Mr Slim just brought up a phase rotation fault when the sparks pulled fuses out one by one. The sparks put the fuses back one be one and two out of the three units showed a phase rotation fault.

ANY IDEA WHY?

Thanks

[superswill]

what works did the sparks do while the fuses were out?

[Brian_UK]

Have you switched the unit off and on again after the sparky played with the fuses ?

[Thermatech]

On the old fixed speed units if you run for any time on 2 phase then the compressor motor windings will burn out. Unit would only stop if control board supply phase disconnected.
On newer inverter units pulling fuses one by one like this could potentially cause damage to the inverter.

I think most 3 ph Mr Slims have always had phase rotation protection because the scroll compressor needs to spin only one direction.

Did the unit run ok after power reset ?

If not then there may be some damage which will need further investigation.

[derekbradbury]

The unit did not still has a fault, two units have a phase rotation fault. one unit was fine. the sparks pulled fuses to do his five year electric test. after his test he put the fuses back and two out of three units have this fault. the units are 7 years old.

[frank]

To eliminate any mains supply problem you need to use a phase rotation tester at the isolator.

We had the same fault occur after a sparky replaced the outdoor isolator due to vandalism, but we traced it back to a faulty mcb - just coincidence with the work the sparky did.

If the Mr Slim can't see 3 phases you get the same fault code.

[JDT83]

:mad:Any Info on why i cant get 12v reading going to controller par21

[cosmaniac]

:mad:Any Info on why i cant get 12v reading going to controller par21

reasons why

no supply on indoor pcb
faulty indoor pcb transformer
burnt fuse and znr on indoor pcb
faulty wire from indoor unit to remote control

hope it helps