How to Check Oil in AC Compressor? 3 Simple Steps

Check Oil in AC Compressor

An AC compressor plays a vital role in a vehicle air conditioner or a household unit.

Therefore, it is crucial to check and maintain it regularly to ensure optimal performance. The oil level is one of the critical things to check when using the oil-injected types.

Oil is needed to keep the pistons and all moving parts on the AC compressor well lubricated, so never seize. Here we explain a few symptoms that indicate you need to add more oil and also how to check the levels.

Common Symptoms Your AC Compressor Needs Oil

Let’s check most common symptoms that your AC compressor really needs oil:

Wear on Rods and Bearings

One of the most common signs you need to add oil to your AC compressor is excessive wear on the rods and bearings.

It typically occurs when the crankshaft does not get adequate oil to keep the moving parts well lubricated, leading to excessive wear.

Leaking Refrigerant

When you notice that refrigerant is leaking from your AC system, this is a sign there are weak points. Oil can also get out through these weak points.

AC Compressor Smoking

If you see black smoke coming from your AC compressor, this is a clear sign that the system is running low on oil.

The black smoke is generated by friction between the moving parts or burning components since there is no oil to cool things down.

Noisy/Smelly AC System

Although weird smells and sounds from your AC system can be a sign of various problems, it is also a good sign the compressor is running low on oil.

Noises that result from low oil are typically faint creaks while the smells are of burnt oil.

How to Check Oil in AC Compressor

Whether you see the signs above or not, it is still relatively easy to check the oil on your AC compressor, and you just need to follow the simple steps below.

1.  Locate and Remove AC Compressor

This method is perhaps what many people use, and it entails removing the AC compressor from the air conditioning system. It is a longer and more hectic method, but it is the most effective one.

Here you first need to locate the compressor on the specific air conditioning system you are using.

This should be easy provided you know the type you have and how it looks like, but the cylinders on most make them easy to spot. Once you locate it, you should unscrew or unbolt and remove it.

2. Drain the Oil

Next, you need to drain out all the oil in the AC compressor into a measuring container. Make sure you only drain out the oil from the drain valve and not any other opening on the compressor, if any.

3. Compare the Oil with Recommended Quantity

Once you drain all the oil into the measuring container, you have to compare it with what the manufacturer recommends.

Perusing through the user manual should give you this information. A quick online search can also tell you the exact amount of oil the specific AC compressor needs.

If what you have in the measuring container is less than what the manufacturer recommends, your AC compressor is low on oil.

You should then return the oil to the air compressor and top up the difference or even put a proper amount of fresh and clean oil before mounting the compressor back into the system.


An AC compressor requires adequate lubrication to keep running smoothly. Oil helps ensure things like the piston move how they should and do not overheat, as this can cause a myriad of issues

You can use various symptoms to tell when you have issues with the oil in your AC compressors, such as burning oil smell and excessive bearing wear.

Also, you can remove the AC compressor and check whether it has enough oil. Regardless of how you choose to check the oil level, the crucial thing is always to make sure there is enough in the system.