questions about refrigerator pressures

[po boy]

I dont work on refrigerators normally but my uncle asked me to take a look at his , so I did.It is a 15 year old refrigerator that just stopped cooling like it should. The compressor and fans come on and run .The compressor will shut off for awhile like the ol is tripping out.I tapped the suction line but am not sure what pressures a refrigerator should run.It is an r-12 system and was running at 30 pounds pressure on the suction when it was running.When it shut off and equalized it was at 80 pounds pressure.Can someone please help me with normal operating pressures .Thank you.

[onetime]

Equalized and running pressures are in the ballpark, check the defrost timer, defrost terminate and evap fan.

[r404a]

Po boy,
Have you determined IF the OL is kicking the unit off? Is this a freezer/refrigerator combo? Try to determine if the OL is what is taking the motor offline. If it is, and you aren't overamping or overheating, you may try a 3'n 1 starter. Like the previous poster said, you could be losing power at a timer or tstat. Good luck.
r404a

[rayr]

Overloads do go bad on domestics. Dumb question but is the condenser coil clean?????? They can get pretty nasty.

[sajan127]

the pressures seem ok, but there are several things you should be sure of before tapping into the lines. comercial refrigeration is ussually small, with a smal charge. once you hook up your hoses, there goes a nice chunk of your charge. therefore I would check all my coils to make sure they are clear, then my fans are working properly, then that my temp control is actually calling.
If it is a refrig freezer combo, and the freezer is still working but the fridge is warm, I would check that the opening between the two are not either blocked by product in the freezer, or iced up.

[t527ed]

30 lbs suction pressure sounds pretty high for r-12 cap tube system. how soon is unit equalizing to 80 lbs.
sounds like could be broken valve in compressor.