How to Check Oil In AC Compressor [Step-By-Step]

April 18, 2023 360

Improper oil levels within the A/C compressor can be devastating to your vehicle. Your A/C compressor needs oil to properly lubricate the system. It stops the piston and other moving parts from seizing.

There is a simple way to check the condition and amount of oil within your A/C compressor. It involves a small tube and some spare time.

In this post, we will cover how to tell if your AC compressors need oil, how to check the oil in any AC compressor.

If you don’t know what type of oil to use in an AC compressor, check out this post here.

How to Tell if Your AC Compressor Needs Oil

It’s important to keep track of how well your air conditioning system is working. It needs a specific amount of oil or it can cause your A/C to fail.

Generally, you shouldn’t have to add oil to the AC compressor once it’s been installed, unless you’re installing a new one or if there’s a leak in the system.

Generally speaking, you shouldn’t need to put more lubrication into your compressor after it has been installed, unless you’re replacing the old one with a brand new one.

Before adding any oil, it’s best practice to clear out the entire system before adding refrigerant or lubrication to it. The refrigerant also has oil in it. There is a simple way you can check if your A/C compressor needs oil. Here’s how you can do it:

Compression Preparation

If you have already decided your vehicle needs oil, you need to check and see which type of compressor you have. It is a dry compressor that needs oil or one that already has oil?

If you are reusing an old one that already has oil, then it has to be drained first. Once the oil has been drained, then you need to add the new oil before re-installation.

If it’s a dry compressor then the appropriate amount of oil should be added before it starts.

How to Check Oil In AC Compressor

1. Purchase Tubes

There are little tubes that can be purchased that attach directly to the A/C low-pressure suction line. These are a cheap alternative to draining the entire A/C system and hooking up to the special machine.

They come in multipacks and are simple to use.

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2. Run The AC

Turn on your vehicle and allow the A/C unit to run for 15-20 minutes.

3. Locate the Suction Line

The low-pressure line or suction line, is usually the bigger A/C line and the cap is usually black, however, on some vehicles, it may be blue.

4. Attach The Tube

Place the tube between your thumb, index finger, and middle finger. Push the tube into the low-pressure line hole 2-3 times while the A/C is running.

5. Let It Sit

Let the oil checker tube sit upright for 3-5 minutes. Once the time has passed, check the tube. If the oil is more than ½ way full, it does not need oil. If it’s below ½ full, add the proper amount of oil back into your system.

How Much Oil To Put in AC Compressor

Having too much or too little lubricant in your A/C compressor can equally cause damage. If you are adding oil into an old compressor, you need to drain all the old oil before adding any new oil.

If you don’t know how much came out of the unit, then you won’t have a clear idea of how much is left inside.

To get the proper amount needed, you have to look up the A/C specifications. It may require a can or two of refrigerant and a little bit of oil.

If you’re adding oil in a new compressor, just remember that most are already filled with lubricant. If you add more, you will end up with too much.

Draining The A/C Compressor

If you find yourself needing to drain the oil from your A/C compressor, it can be done in a few steps:

Step 1: Remove It

Remove the A/C compressor completely.

Step 2: Prepare

Prepare a measuring device such as a measuring cup. Remove the cap off the rear of the A/C compressor and pour the oil in the measuring cup.

Make sure the measuring cup is clean and free debris before pouring the oil in.

Step 3: Add

After you have emptied the oil out of the compressor, add the amount recommended by the manufacturer. The recommended amount should be stamped on the compressor.

Step 4:

After all the oil is put back in, you are going to want to spin the clutch plate to cycle the compressor approximately 3-4 complete revolutions. The clutch plate is the black circular piece.

Preventing A/C Compressor Failure

It’s important that you follow some common practices to avoid the failure of your A/C compressor.

1. Flush The System

If you hear noises within your compressor, this could indicate internal failure. This could happen due to particles making their way within the unit.

They will mix with the oil and move through the A/C system. If this happens, flush the system as soon as possible. However, flushing the system will not remove all the oil. It will only remove air and moisture.

2. Remove Particles

Unfortunately flushing the system won’t get rid of all the debris inside of it. In this case, you will have to disassemble the unit and replace the clogged parts. Generally, it’s the condenser that will clog up. This will need to be replaced.

3. Use The Proper Lubricant

The wrong lubrication will lead to compressor failure and damage to other components within the A/C system. Make sure you use a lubricant that can adequately mix with the refrigerant your system requires.

4. Drive Carefully

It’s hard to do sometimes, especially if you live in the country, but you should drive with caution on bumpy roads.

The bumps can impact the longevity of your A/C compressor. It’s very important that you service your A/C compressor regularly. You can do it yourself or to a trusted mechanic.

Your A/C system has cylinders just like your car’s engine, except the cylinders in the A/C compressor help compress gasses. It works hard and sometimes the system will need to be maintained.