Hi, I was asked to go and have a quick look at a beer display fridge yesterday evening, it is a J&E Hall condensing unit....unfortunately I don't have the model to hand. The data plate says R404a but at some point the compressor looks like it has been swapped out for a R134a compressor....which I know J&E Hall have units which you can choose which gas it runs so unsure if this is what the original compressor was or if the original was a r404a one. I checked to make sure the expansion valve was r134a and it is.

The paper work the last engineer left said he re-gassed the unit with R134a and put 4.3kg in, the sight glass is flashing through and for some reason it is tripping the HP switch even though it is set at 250psi. I couldn't tell you what the running pressures are on the high side as there is only one service point on the system and that is on the suction right before it goes into the compressor (not a rotor lock valve).

The discharge air from the condensing unit doesn't feel warm at all, the compressor seems to be running warmer than you would probably expect but not boiling....I suspected that there may be possibly air in the system and this is why the symptoms are like this? I have never come across this before so abit bemused by it...according to the guys paperwork all he has done is pressure test the system with nitrogen, repair a leak on a rotor lock valve on the receiver and re-gas!? I have also checked the condenser coil and it is clear, but I know from previous jobs even if it was blocked you would feel the excess heat and there doesn't seem to be much.

From what the customer told me the unit seemed to get down to temperature ok when it was first done but after a few days began not working. Anyone ever come across anything like this before...I have to go back Monday to try resolve the problem, so just wondering if I was going down the right track by reclaiming and recharging?

Thanks