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View Full Version : Removing 1 cassette from a VRF



marc5180
27-02-2008, 07:32 PM
I was sent to a job today at the airport and asked to take out a cassette from a room that was being turned into a walkway. I was told that it was a split unit so should be relatively easy.
Once i got there i noticed straight away that these were in fact from a Mitsubishi Electric VRF. My problem is these have been installed with no reference of how many indoors are fed from the outdoor. I have managed to find 5 but there could be more, nobody knows.
I plan on pumping the unit down, the standing charge is 10KG plus additional which again i dont know 'cos it hasn't been written down:mad: and whatever is left then i will reclaim it.
When removing the cassette and the pipework can i cut the pipework back as far as i can to the refnet and just braize them up?
Also what about the wiring "daisy chained" into the unit? Can i just connect these together in a block connector? There is ony 2 cables coming in, one in and one out to the next unit so i imagine that i can but what else will i need to change? Will i have to change address settings on the outdoor PCB? If i do i dont know what address this cassette is because it hasn't been labeled up.

Lastly before i left the spark took out the fuse spare to the indoor unit ready for removing tomorrow but then on another controller off the same system a fault flashed up after about 30 mins which said 051 ( outdoor unit?) then 1102 and it said 0DegC on the controller.
The model number for the indoor is PLFYP20VCME.

Thermatech
27-02-2008, 08:45 PM
The 1102 fault is excessive high compressor discharge temp. The No1 cause for this is short of gas. Best check it out first before you proceed other wise the customer will complain that the system only had a fault after you did the work on the system so it must be something you have done wrong.
So I suggest recover all refrigerant from the system. Calculate the total charge for the system based on the liquid line pipe sizes & lenghts to see if it was SOG.
The control cable is 30v d/c, you can remove it from the indoor unit & make a good connection with crimps or terminal block instead, but when you do this the system will show a communication fault because the outdoor unit cannot get any reply from the indoor unit you have just removed.
The indoor unit will have some address setting dip switches so you can check the address.
All the time the outdoor unit is connected to the indoor unit with 30v control cable it can communicate even if the 240v is disconnected at the indoor unit.
After you have removed the indoor unit & made good the pipework & control cable when you power up the outdoor unit again it might stop on a communication fault bacause it cannot get any reply from the indoor unit you have removed. In this case you will need to do a virgin restart procedure with the SW2 dips on the outdoor unit.

There is a way using the engineers mode on any connected remote controller to find out all the connected address settings & type of units in the system but its a bit to involved to describe here. It would help you to know how many units you need to look for in the building.

Hope it goes well but if you need help the lads on Mitsi tech help desk are very good.

Brian_UK
27-02-2008, 09:14 PM
Is this one of those times when you wish that you had a decent pipe crimping tool. Then you could simply crimp the lines off, use a line tap or similar to suck out gas, cut the pipes, braze the ends and drop the kit out.

Oh, were it that simple ;)

marc5180
28-02-2008, 07:33 PM
I went back to the unit today, spoke to a guy from mitsubishi called Matt who was very helpful. He explained that i could set the dipswitch on the outdoor board to count how many indoors there were. I found 11 so i then turned off all power to each indoor unit then on SW2 turned dip switch 2 and 3 to on whicxh performed a virgin restart and re configured the address settings. I left this on for 5 mins then powered down turn all dip switches back to normal then turn all indoors back on then power up the condensor. No faults flashed up and the unit ran like a dream.
Thanks for the help

Springbok
28-02-2008, 10:33 PM
Its true what they say,you learn everyday.By one engineer troubleshooting a unit like that,and fixing it,by sharing your experience,now it shows us all what to do when we stumble across a job like that.Nice job,Marc5180...

marc5180
29-02-2008, 07:04 PM
Thanks Springbok:D