Our all components and refrigerant pipes are new. As far as we know, Compressor is sold with oil inside of it.

Do you think should I add extra oil into system after I assemble all system or Is the oil inside of compressor enough for entire new system ?

e.g If compressor has 130 gr. Is that mean 130 gr will be amount of our refrigerant system or Do I have to determine how much oil should be in the refrigerant system ?

I have read somewhere about OCR (oil circulation ratio) and return test but I dont know how to use these test to determine exact amount of oil in a new designed refrigerant system.

Kind Regards


When they did mine, having fitted a new condenser and compressor, the first operation was to use the machine to evacuate the system and it reported X grams of oil.

Then it was tested to see if it held the vacuum (well actually pressure below atmospheric...)

After that the machine filled it with the refrigerant and oil as needed.

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    As you said sir, It is a method to add oil back to system as much as extracted from the system. But my system is empty and I have to determine amount exact oil. – engineercyprus Jul 19 '19 at 8:30
  • @engineercyprus did you not read - new compressor and system empty except for what was in the compressor? – Solar Mike Jul 19 '19 at 8:32
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    All components are new and compressor came to me with oil inside of it. So I dont know either I should put the system more oil or the oil inside of compressor enough for system – engineercyprus Jul 19 '19 at 10:42
  • Whenever a compressor is replaced, one should forget about the machine's oil injector. Oil has to be added directly to the compressor in this case, or it will run dry and seize the first time you start it up. Only use the machine to inject any quantity of oil that won't fit inside the compressor without spilling over, but this applies only for large systems such as stand-alone driver's AC for buses (the one that won't depend upon the passenger's AC system)... – Al_ Jul 20 '19 at 21:59

Provided we're speaking of an OEM AC system, there are refrigerant and oil tables available online, which list the correct oil amount for every car. If 130 mL (oil is measured in volume, not weight) is what you have inside the compressor (drain it into a graduated container to be sure, anyways), and the table lists 130 mL of oil for your car's AC, you're perfectly fine. Otherwise, make sure you have the correct amount of oil inside the compressor (keep in mind that having 10mL in excess or being short of 10mL won't hurt anything). The same compressor can be fitted on multiple vehicles with different lenghts of piping and this means that the oil amount can vary between vehicles, especially whenever the vehicle comes with a "rear AC" option.

If you have an instruction sheet for the new compressor follow it, but keep in mind that generally speaking, before the engine can be allowed to turn the compressor's shaft, you have to rotate the compressor's shaft by hand (rotate the clutch hub if compressor has a clutch, or pulley if it's clutchless) about 10 times clockwise and 10 times counterclockwise so that it's correctly primed and no hydrolock happens; and switch the blower fan on at maximum speed before engaging the AC (or turning engine on if compressor is clutchless; in that case also turn AC on before switching engine on)/maximum cooling if car has automatic climate control; the same for any rear AC system; all of this ensuring that the engine stays in idle all the time. This has to be done for 5 minutes. This is because the evaporator/evaporators has/have to be loaded with heat so that the expansion valve/valves is/are fully open and that huge oil amount that has been put inside the compressor is able to freely circulate through the system, fill all the components and then return to the compressor with little or no damage experienced by it... this is called running-in of a new compressor...

Also, make sure the oil provided inside the compressor is actual refrigerant lubricant, and not assembly oil...

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  • Don’t need to go online, with the machine used on my car you enter make, model& year and it has the data from its own databank. The supplier sends out updates as well. – Solar Mike Jul 21 '19 at 5:34
  • Personally, i don't trust this option too much. – Al_ Jul 21 '19 at 10:41
  • I have seen the machine and I trust it more than you... – Solar Mike Jul 21 '19 at 10:43
  • Thank you for your answers. Unfortunately, I have no data online for my system as it is made by me. So, everything is sole. As far as I understand from your answer, I dont have to put any additional oil in case If I dont have long distance pipes and rear AC. In this case, The oil inside the compressor would be enough for whole system. Is it right ? – engineercyprus Jul 22 '19 at 5:32
  • I can't give you a definite answer, too much oil and the condenser and evaporator get fouled and exchange heat poorly, not enough and you damage the compressor. Determining the proper oil quantity is a hard task. It's everything at your risk. – Al_ Jul 23 '19 at 13:03

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