Oil in evaporator

[SULTAN]

I found a system with MinusForty Refrigerator with blocked capilary causing system to cycle only around -6f and not reach its designed temperature of -20.
To get to capillary you have to take the suction line off the evaporator also. When i took the both line off the evaporator i found it flooded with oil.

Can someone explain me the phenomenon as to why oil accumulated in the evaporator from just have a blocked cap tube. Is it because the partial block causes the flashgas to escape and not enough pressure for oil to return back to the accumulator?

[Tesla]

Hi SULTAN
Two main reasons. 1; Operating at lo loads reduces the volume flow rate of refrigerant in turn reducing amount of oil moved out of evap. 2; Oil migration when comp is off. Having a restriction (partial block) will reduce volume flow rate causing more oil to accumulate.

[SULTAN]

Thanks tesla.

I have another problem now. I was brazing the drier off the liquid line and i noticed a **** load of oil accumulated in the lines there also. My co-worker condems the compressor. Should i go ahead with changing of compressor or just ignore the oil and just vaccum everything off?

[amitsaxena]

Dear.
No need tp change the compressor, as it is a natural phenomenon while the capillary is blocked at capillary and drier joint.
You just dont change the comp. If possible then charge slightly more gas may be <5% so that it can take care of extra heating of the comp.
Or try with the same charge if not much oil is spilled out.
thanks
amit

[Tesla]

Hi SULTAN
Normally to rectify an oil logged evaperator we would run the compressor for 2 - 6 hours at full load. So you may need to give it a few extra defrosts and increase the load with heat. To check if your compressor needs replacing close the suction valve and run comp into a vacume around 20 or so inches, then stop comp and see if the vacume creeps up slowly or shoots straight up. If the comp is on its way out it wont pass the vacume hold test - if this were the case it could also cause oil to log in evap. If the comp is ok the oil should go back to comp - if you have drained out some oil it may need a little more, contact comp supplier for data on this. Good luck and please let us know how you go so we learn a little too.