Helo;

I am a new member in this forum. I am working in a manufacturing industry of Split air conditioners. Normally; the vaccum pumps are used for evacuating the nitrogen gas and for creating the vaccum for gas charging in the air conditioning units. I have encountered a problem during my 3.5 years service. We found oil in the tubes connecting with the Vaccum pump and the Air conditioning unit. It happened very first time. Can some one help me out how it happened because normally the pump evacuate the gas not the oil from the compressor.
Waiting;

Regards,

Waqas