Oil in a AC compressor is there so that the mechanical parts don't over heat from friction
To prevent wear on the compressor.
The compressor oil
Oil
I'm in the process studying for my epa test and this is one of the questions and their answer is foaming occurs in the compressor.
To return oil to the compressor.
to lubricate the compressor
Sludge in a refrigeration system can lead to reduced system efficiency, decreased cooling capacity, and potential damage to components such as the compressor. It can also cause blockages in the system, leading to uneven cooling or system breakdown. Regular maintenance and proper filtration can help prevent the formation of sludge in a refrigeration system.
mineral oil
Did you add an oil charge to the system when you recharged it and did you recharge the system using refrigeration gauges. The system may be low on refrigerant oil or you could have overcharged the system causing the compressor to have to work too hard.
freon and oil
It's a Lubricant. It lubricates parts.
Ice