difference in pressure

[portwolf]

when a compressor is switched off should the pressure drop on the high press side?

[mikeref]

Yes, and in capillary systems, the pressure will try to equalise with the low side.

[portwolf]

thx mike. im not a technician actually a electrician, but i went out and bought gauges, flaring tools etc. i have successfully repaired a couple of fridges, but i got stuck today on a coldroom and a fridge. the coldroom i suspected a gas leak. the compressor was drawing a vacume on the low pressure side. but as soon as i added some r22 the high side got too much pressure and the compressor cut out. but then it stayed in vacume on the low side and verry high on the pressure side. could there be a blockage?

[mikeref]

thx mike. im not a technician actually a electrician, but i went out and bought gauges, flaring tools etc. i have successfully repaired a couple of fridges, but i got stuck today on a coldroom and a fridge. the coldroom i suspected a gas leak. the compressor was drawing a vacume on the low pressure side. but as soon as i added some r22 the high side got too much pressure and the compressor cut out. but then it stayed in vacume on the low side and verry high on the pressure side. could there be a blockage?
O.K, definately trouble has found you. There is a restriction in the system and now too much gas as well. Since you are "new" at this, i'm not sure how to get you out of trouble. I'd be looking at the expansion valve on the evaporator first as it may have closed down for various reasons. How did you come across this coldroom fault?.. mike

[portwolf]

it belongs to a friend who owns a liq.store. he also has a undercounter fridge using r134a when switched on the compressor runs about 30 seconds, before cutting out from over heating.

[mikeref]

it belongs to a friend who owns a liq.store. he also has a undercounter fridge using r134a when switched on the compressor runs about 30 seconds, before cutting out from over heating.
The undercounter fridge would be something you can do. Check compressor amps against nameplate RLA, then test capacitors are fine. Make sure condenser fan runs when compressor started and condenser(radiator) is free of dirt buildup on the fins. Let me know if the results. Ask if the compressor was noisy before this happened.. mike

[NoNickName]

There are a number of threads in the forum asking why the compressors don't keep the vacuum after pumping down, while here you have a compressor which actually pumps down and one dares to complain?