All you need to do is fill the new ac compressor with exactly the same amount that you drained out of the old ac compressor.
How to drain oil from car ac compressor.
Empty the air conditioning compressor of all the oil by holding the open end down while rotating the clutch by hand in the normal direction of rotation.
The next steps must be done in a near sterile fashion.
You may be lucky enough to find the type of oil on the same sticker that lists the weight of refrigerant your system requires but if not the only place to reliably find the amount of ac compressor oil your system requires is by calling a dealership for your make of car.
If you don t have the owner s manual look up the make and model of your vehicle online to find information about your ac compressor.
However the easiest way to tell exactly how much oil needs to be in your specific ac compressor is to drain the old compressor and measure the amount of oil that comes out.
Place an order for any of the replacement parts at buy auto parts.
Putting the wrong oil in your compressor will damage it.
Buy auto parts carries a wide range of parts for every car make and model.