Compressor crankcase

[Bobfd7dbf]

Why does the crankcase of the compressor is the lowest pressure part in the refrigerant cycle ?
So that refrigerant migrates to it when the system is off.
Thanks in advance

 

[Compositepro]

Because the compressor draws its suction flow from the crankcase.

 

[Bobfd7dbf]

But when the system is off, the pressure difference between the suction and discharge does not exist and pressures are equalized.

If refrigerant is left in the evaporator when the system is off it migrates to the crankcase (lowest pressure part in the system) and causes problems.

So why does the compressor crankcase pressure is low when the system is off??

 

[Compositepro]

When the compressor is off, the pressure everywhere in the system equalizes, obviously. Any liquid will end-up in low spots or colder spots.

 

[berkshire]

To mitigate this problem, some compressors are fitted with a crankcase heater to boil off any residual liquid refrigerant.
B.E.

You are judged not by what you know, but by what you can do.

 

[GT-EGR]

Any pressure difference you are seeing is probably from external influence, mainly ambient temperature. So if it’s colder outside than inside, there will be some difference/gradient in pressure depending on how extreme the temperature difference is.