Mitsubishi Close Control

[techni]

I have two 60kW Mitsubishi Close Control unit in a data room that are tripping out the compressors at low ambient temperature. No faults are showing on the controllers or mitsubishi laptop. Mitsubishi cant give me a reason, anybody any ideas.?

[Brian_UK]

When you say "tripping out the compressors" what exactly do you mean?

Is the power MCB tripping, is the compressor klixon tripping, etc?

Also, the model number would be helpful.

[Thermatech]

Can you look at the fault history record at the outdoor unit to see if there are any preliminary faults.

Preliminary faults are not displayed at the remote controller & can sometimes give an idea what might be the problem.

Do the compressors restart after a period of time or only after power reset ?

[Greengrocer]

I have two 60kW Mitsubishi Close Control unit in a data room that are tripping out the compressors at low ambient temperature. No faults are showing on the controllers or mitsubishi laptop. Mitsubishi cant give me a reason, anybody any ideas.?

Are these downflow PFD-P500VM-E indoor units with 2 x PUHY-P250YHM-A outdoor units?
If so the Tech manuals for these are on the 2009 Mitsi Tech CDROM. These manuals are large (over 180 pages).
Check the minimum outdoor operating temp for these systems with Mitsi (I couldn't find any info in the stuff I had). If the min ambient operating temp in cooling for these systems is only -5c then this will be your problem in the cold weather we are currently experiencing. There's probably a suction line, evap or ambient sensor somewhere that's locking out or holding off the compressor. However, it's strange that no error code is displayed to inform you of this. Stranger that Mitsi could not offer any detailed info!!
With a bit of luck a Mitsi specialist will offer some further advise on this site shortly.
We've had quite a few call outs recently on splits on server rooms that have stopped cooling operation due the low ambient temps. Most systems are good for -5c ambient in cooling mode but -15c is the normal requirement for UK applications. Having said that Oxford & Scotland saw -17c & -20c respectively recently so even systems capable of operating down to -15c would have been in trouble. Even some of the specialist DX close control systems (Airedale & the like) won't run below -15c / -20c without special modifications.
Good luck.

[techni]

Sorry for late reply but I have been out of action due to illness, Mitsubishi put the problem down to software and upgrade this so that the units ran. When the unit did'nt cool at low ambient the compressors still ran , just did'nt cool the room, we had temperatures of -10 with a wind chill of -25. I presume they upgraded the software to run at a lower ambient.

[Paultighe]

I only heard today that the indoor unit software must be updated, the wrong software was installed, check, below v1.03 must be updated.