Got called to a fault yesterday at a restaurant that we have just taken on. the fault was no cooling from the indoors.

After looking around i found that the system was a twin with refnets (not 2 seperate circuits). Both indoor fans were running although there was no cooling. I went to the condensor and the compressor was running, condensor fans were running so i decided to put on my guages.

On the suction i had 4 bar and the discharge was 15 bar (R410A), i went down to the van to get something then i came back up and the pressures had dropped to 1 bar suction and 4 bar discharge......easy, i thought....it's short of refrigerant. As it was late on when i got the call i told the manager i would be back tomorrow with a reclaim bottle to sort it out.

Today i went back, i recovered 400g. the standard charge was 4.3kg for up to 30m.. whoever installed this didn't write on how much additional refrigerant was added (this really does annoy me). The pipes disappear through ceilings, walls and floors but i think the total run is about 40m for the 2 of them. I pressure tested the system up to 25 bar and connected my gauge lines to the service ports as i always do, checked everywhere for a leak and i found a small leak on a schrader near the 4 way valve. Once it was fully vacced out i recharged but only managed to get in 2.5kg, i tried to start it up but i couldnt get it to run for long enough. The condensor fans would start up then the compressor but it would only run for a few seconds. I spoke to a guy from daikin who told me how to put it on test, i did this and managed to get the standing charge in it.
However when it was running the high side kept shooting up to 35 bar very fast as though there was a blockage somewhere, i checked that the expension device in the condensor was working and also the 4 way valve- they both were. When i turned the unit off by the isolator the standing pressure was 22bar, i told this to the daikin guy and he said there must be nitrogen still in the system. He asked me how i had pressure tested it, so i told him and he said i should never pressure test from the service ports because nitrogen can get trapped ( it's news to me) he advised to reclaim and vac out again- which i did