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Highlander 007
16-06-2017, 12:44 PM
Hi all,

I wonder if anyone could help. I have recently installed a Mitsi Elec. VRF unit PUMY-P200YKM with 6 indoor units.
Commissioning went fine, added 6 kg 410A. It worked for a couple of days and the the customer said it is not doing anything.
Went on site and compressor wouldn't start. Eventually fault code 4100 comes up which is power issues or seized compressor.
Got in touch with mitsi and carried some checks as per their recomendations and they said compressor need replacing. I asked for an engineer to come to site and they said we had to wait for a month.
Long story short, client decided to buy new unit.
Recovered gas. installed new unit, connected pipes and cables. Pressure tested with nitrogen and something strange happens, when i pressurise from the high side, no air comes out of the low side even though i have removed schrader valve pins.
i pressurised the low side, and a tiny bit of air comes out of the liquid pipe and if i shut the valve on the hose, eventually the pressure equalises on both sides but it takes a good 5 minutes to do so.
let the nitrogen out from the pipes and some oil came out too which was the reason why i wanted to use nitrogen so i could get the oil from pipework out.
tried same thing again and same happened.
Evacuated the system from one side and it wouldn't pull from the other pipe.
I need to go back there tomorrow and this has been haunting me for 2 days as my initial thought was that there might be a kinked pipe somewhere (builders still workin in basement).
Has anyone come accross something similar ? Could it be that all the Expansion vlaves on indoor units are stuck in closed position ? if so, how can they be released ?

Any ideas are welcome.

narkom
16-06-2017, 07:43 PM
I guess that indoor units LEVs remain closed during your pressure test.