Do I Need to Add AC Compressor Oil?

ac compressor oilLike any mechanical system, it’s important to make sure your air conditioning system stays lubricated, and AC compressor oil is the lubricant for the job. Your AC compressor requires lubrication for proper functioning and a long life because anytime you have metal parts rotating or sliding they will fail quickly if they aren’t properly lubricated.  This failure comes from quick wear and excessive heat buildup.  The AC compressor in your car is working hard to compressor refrigerant, often R-134a, in order to allow that refrigerant later to expand and create the cooling effect used to cool the cabin of your vehicle.  The process will create a lot of heat and damage if it’s not properly lubricated.

One of the most important things required for a compressor to operate is a good tight seal in the compression chamber.  Your AC compressor creates a low pressure to draw refrigerant into a chamber.  That refrigerant is then compressed to a high pressure either by a piston or a rotating vane and forced out of the chamber into the high pressure side of your air conditioning system.  It is extremely important for there to be a tight seal around this compression chamber.  If there isn’t a tight seal, high pressure refrigerant can leak backward into the compression chamber negating the compression effect, or fluid that is being compressed can slip around the pump back into the low pressure side of the air conditioning system again negating the compression effect.  To help keep the seals tight in your AC compressor, it’s important to make sure there is enough AC compressor oil in your air conditioning system to ensure proper lubrication to maintain the tight seal in your compressor.

Every automotive air conditioning system comes from the factory with the exact amount of refrigerant the system requires and the exact amount of AC compressor oil pre-installed.  Often times, you can find an information sticker about your air conditioning system under the hood of your car listing the amount of refrigerant in the system by weight and the amount of AC compressor oil needed in a dry system.

The difficulty of working on an older AC system is that it is impossible to tell how much AC compressor oil is in your system.  For example, if you’ve had a slow leak for a year, you don’t know how much oil may have leaked out with the refrigerant.  If the leak is high in your system, it could be very little, but if the leak is low or on the low pressure side of the system it could be a significant amount of oil.

Another thing to consider is what type of AC compressor oil your vehicle requires.  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’re replacing just a component or two of your air conditioning system, there are some general guidelines you can use to estimate how much oil will be in those components when removed and therefore needs to be replaced when you recharge the system.  You can find those guidelines and other AC compressor oil information by reading this article about A/C Compressor PAG Oil

Once you’ve got the correct type of oil, you can use the Red Angel Oil Injector to add the AC compressor oil to your system.

You can find the Red Angel Oil Injector and other Red Angel AC products at any of our partnering auto parts stores like:

  • AutoZone
  • Advance Auto Parts
  • Bennett Auto Supply
  • CarQuest Auto parts
  • NAPA Auto Parts
  • O’Reilly Auto Parts
  • Pep Boys
  • Fast Track
  • Bumper to Bumper Auto Parts Specialists
  • S&E Quick Lube Distributer
  • DYK Automotive
  • Fisher Auto Parts stores
  • Auto Plus Auto Parts stores
  • Hovis Auto & Truck Supply stores
  • Salvo Auto Parts
  • Advantage Auto Stores
  • Genuine Auto Parts stores
  • Bond Auto Parts stores
  • Tidewater Fleet Supply
  • Bumper to Bumper Auto Parts
  • Any Part Auto Parts
  • Consumer Auto Parts

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ac_compressor_oil.jpg – By Phantom 1311 – Licensed by Getty Images – Original Link

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4 responses to “Do I Need to Add AC Compressor Oil?

    1. Justin,

      Thanks for your question. Unfortunately, you need a little more information to determine what’s wrong with your air conditioning system. Your next step would be to have the system pressures checked, both high and low sides. If the pressure rise across the compressor is lower than it should be, it would indicate your compressor is indeed bad.

      Thanks again for your question!
      -BD Auto Pro

  1. I have to replace my compressor with a secondhand one in my 2000 E240 Mercedes. Do I need to add oil with the R-134a refrigerant.

    1. Kgapa,

      Thanks for your question about your 2000 E240. Before installing the new compressor you should have your system completely evacuated of refrigerant and oil and drawn to a vacuum. Once you install the new compressor, have the system evacuated again to a complete vacuum, then add the correct amount of refrigerant along with the correct amount of oil for your car. There should be a sticker on your radiator support or on the underside of your hood stipulating how much refrigerant and how much and what kind of oil to use. If you can’t find that sticker, you can always call your local Mercedes dealership for those specifications.

      Thanks again for your question!
      -BD Auto Pro

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