mitsubishi vrf problem!

[airconadam]

hey again fellas got called to a system today in an old peoples home only 18 months old
PURY-P350YGM-A, found controllers faulting 6602 and main g50a controller faulting 6607 all mnet/comms problems. Spoke to mitsi advise of power down and full power up but i had one slight problem which is acces to fan coils etc so not able to power down every indoor evap:mad: also in the meantime the maintenance fella told me of a problem about tha main electricity into the building which had apparently worked loose on a phase and touched and earth or something and has caused tellyvisions to blow sockets,lights,fish tank in peoples rooms etc etc so straight away i thought that isnt good. after looking at some of the controllers some was faulting 6602,others wer showing HO and some would turn on show temp etc then knock off without the unit actually running,spoke to misi once again and he said its defo power problems! he told me to check every unit has got 240v to it which i could only check on a few and also check the bc box which iwas unable to get to,all i can see is the fuse spare which is turned on. Then i also seen one controller flashing up 062-6602 then bc in top corner which now tells me bc box problems?? also done a check on the controller to see if the controller was reading the indoor evap ie setting on controller was 12 got to the setting in the controller press test twice which showed 88 when it should show ic but does this mean that the board has gone in that unit i didnt get chance to try it on every unit but will do tomoz. Hopefully i will be able to gain full access to the bc box and see how it goes from there if any body can add any suggestions or comments please feel free to help me:D
thanks alot

adam

[Thermatech]

With a major power supply problem there is the potential for every circuit board in the system to be damaged.

The 6607 faults at the G50 is the place to start.
The G50 is reporting that it is not getting any communication reply from the units listed.
So you need to locate the outdoor unit, BC & all indoor units & look at the units with address that the G50 cannot see.
The 30v d/c m-net communication is made at the outdoor unit & without this none of the remote controllers would have any display.
If the G50 cannot see the outdoor unit & all units which it is connected to then the outdoor unit circuit boards are most likely damaged.


Make sure the customer will pay or is covered by insurance as this could be very expensive.

Note
1/ HO at remote controller means the controller cannot complete electronic hand shake with its relavent indoor unit.
2/ When remote controller goes blank a few seconds after switch on that means no 240v power to the indoor unit.
3/ 88 means remote controller cannot get any reply from the indoor unit.

[airconadam]

thanks alot thermatech was hoping you would reply:) when you say about 88 on the controller,cant get a reply from the indoor unit does that mean the board is knackered or not nessecerily. Also iknow the g50 cannot see 11 units which are all the ones on the one vrf,only 5 of them have hard wired wall controllers iwas told that they will all have the 30v m-net communication but some of them have not got mains power?? they all have a display on them aswell? iwill check at the outdoor first thing tommorrow thanks alot

adam

p.s

[Brian_UK]

If there have been major power problems don't forget to double check your neutrals when you are going around the system.

Line to earth doesn't always tell the whole story.

Good luck with it, it sounds like it's going to be a long day there....;)

[Thermatech]

How did you get on at the old peoples home today ?

[airconadam]

great! after gaining access to the bc box ichecked for mains power which i had,also checked the m-net ihad 30v i then checked the transformer and i had 24v going onto the board. Spoke to mitsi told them they said thats all i could check so luckily on site was another bc box i changed the board and bingo it worked so board needed. Now on one of the units it would turn on like yesterday but wouldnt run and then turn itself off so i take it that board has also gone i could only reach to the electrics and test for mains power to it need another access hatch:mad: thanks alot

adam

p.s when i told mitsi it had worked they was suprised and said thats a new one?? must be due to the power spikes??

[airconadam]

hey again fellas a follow on from the problem! after last week when i said a new board was needed on an indoor which was a pmfy-p20VBM-E. Changed the board,done a virgin restart, the system ran up fine and all units were cooling and heating:D but this one indoor unit which i had put the new board on, the fan wouldnt run:mad: i checked the fan was gettin power on the connector on the board and i was getting- between 1&3 1&4 1&5 1&6 all 349VDC then i tried it to earth and from 1,3,4,5,6 to earth was all 114VDC so does this mean the fan motor is knackered????? i could here the gas going through the fan coil just the fan wouldnt run thanks alot

adam

[Daikin=Overated]

I take it you've tested the fan motor capacitor before you condemn the fan motor???

[airconadam]

the fan motor just plugs on to a connection on the board so if there is a capacitor on the board its is a tiny one??

[Thermatech]

On those little one way blow units there is only the one circuit board & the address dips circuit board.
So if you have fitted a new circuit board & you are sure all dips are set correctly & the fan motor is plugged in properly then the only other possibility would seem to be the fan motor.
The wiring diagram does not show any capacitor.

If you have another one way blow unit on site you could always compair the resistance of the motor windings.

[airconadam]

thanks alot thermatech also a another question is! they dont look easy to change.Never done one on that model before looks like the easiest way is to drop the v shape coil???? thanks

adam

[marc5180]

I've never replaced the fan motor in one of those but i think that the coil will have to be dropped out of the unit to be able to get access to the coil because as you say its a "V" shaped coil and the fan motor is above it....Rather you than me:D.

If thats the case you will have to disconnect the suction and liquid pipes as well. Not sure how you would go about doing this, i think you would have to pump the system down to get as much refrigerant into the condensor and then reclaim what ever is left or maybe there is a way of closing solonoid valve for that unit in the BC box, im sure Thermatech will know

[Thermatech]

Sorry mate I have not yet seen one of these units taken apart.

For sure its not going to be easy.

[airconadam]

ok no prob thermatech what about the removal of refrigerant or is it possible to close the bc box valves???

adam

[Thermatech]

The B/C valve have teeny weeny pressure equalising orrafice so thay dont ever completely shut.

You will have to pump down / recover.

[airconadam]

ok thanks alot for all your help:D

adam

[airconadam]

just a quick update changed the indoor fan without pumping down and recovering,droped the tray etc and coil just enough to get the fan motor out and new one in

adam