compressor problem

[dunny123]

Hi,went to a call today,{ice cream display freezer} high in temp.compressor seems to run ok,but its quiet hot.But by the time it gets to the condenser the pipes arnt hot,cond not hot at all.iv reclaimed the gas,{wanted to weigh the gas in,due to someone else already worked on it}to make sure right amount was in.I replaced the drier,and sent a bit of nitrogeon through the system to make sure there wasnt a blockage in cond.Gas came out of cond fine.Replaced drier,vaced out,then weighed gas in.Still did same again.When i switched unit off,you can hear gas hissing for about 10seconds then stops.I know there isnt a leak on system,as pressures are same.Iv come to the conclution that gass is passing through seals inside comp,this would explain comp not pumping propley,and the hissing sound.Im a young enginner and realy want it confirming that iv made the right diagnosis before i replace comp.Thanks

[richelli]

Sounds like your comp is goosed. When its running is the suction pressure higher than would be expected? when switched off does the suction pressure rise up very quickly. If its passing really bad you can normally hear the hissing sound you talk about. If it has a suction valve shut the valve and see if it can pull a vacuum. Not an ideal test but it will tell you a bit. If it does pull a vacuum switch it off with the valve still shut and se how quickly the pressures rise up. If its passing back from the discharge the pressure will shoot up. Some things to try anyway.

[dunny123]

Yeh the suction pressure does rise very quick.
No it has no valves,its only a small unit,capil tube.

[piersons_man]

Sounds like the discharge valve in the compressor is not seating properly, when the unit is switched off the gas 'hisses' back past the valve causing the suction to rise like richelli mentioned.

[Slatts]

As the others said Dunny, the compressor is, as we say in the trade, stuffed.
I assume the compressor is hot to touch?
It's not pumping mate. The fact that the discharge line is cool at the condenser says it all.
Change the compressor, its electrics, the drier and cut the 1st inch off the capillary. Vac it out and weigh in the charge and make a name for yourself.
you know how to cut the capillary with a 3 cornered file?
Good luck mate.

[dunny123]

Thanks for all your replies guys,brilliant.
Confirmed what i thought.
Thanks again.