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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30 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. Melba,

        Thanks for your question about your air conditioning. Most of the time, when your AC only works at higher speeds it is because your fans aren’t doing a good enough job cooling the condenser at low speeds. This could be due to faulty fans, or a problem with their electrical circuits like a blown fuse or bad relay. This also could be an indication that your system is low on refrigerant or your compressor is starting to wear out. You can try checking your low and high side pressures to see if this might be the problem.

        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

    1. Bobby,

      Thanks for your question. You can over oil an air conditioning system which can clog the dryer and cause problems in the compressor. Since the oil spreads out through the refrigerant there is no way to measure how much oil is in your system. The only way to have the correct amount of oil is to evacuate the entire system then add clean refrigerant and the manufacturers recommended amount and type of oil.

      Thanks again for your question!
      -BD Auto Pro

  2. I have an 98 Altima, and someone my wife took the car to emptied the refrigerate from the high side. Now, I’m having troubles getting the air cold again. Once I checked and added more refrigerate and oil without overfilling it comes on cool for awhile then turns warm after a few good mintues. Do you have any suggestions besides taking it to a dealer or mechanic?

    1. Minus24,

      Thanks for your question about your 98 Altima. If your air starts off cold but turns warm again it sounds like your system may be overfilled or have a clog somewhere. If it was overfilled the pressures could get extreme after running for a short while causing the system to trip off. Similarly, if there is a clog it could restrict flow more so as things heat up causing the problems you’re experiencing. Our advice would be to get the high and low side system pressures checked to look for a clog or to show that the system is overfilled.

      Thanks again for your question!
      -BD Auto Pro

  3. I am replacing the compressor, condenser, drier, and 2 lines. All of the components are denso and the new compressor comes with a complete system charge of oil. My question is do i need to measure the oil if im replacing all of that?

    1. Nate,

      Thanks for your question about adding oil to your system. If the compressor comes with a complete charge of oil you shouldn’t have to add any more oil to the system. There should be a sticker on your radiator support or hood that tells you how much oil and how much refrigerant the system requires. Our recommendation would be to make sure the amount of oil that came with the compressor is close to or equal to that amount.

      Thanks again for your question!
      -BD Auto Pro

  4. I recently replace my ac compressor and dryer, and expansion valve. 06 town and country. Before I did that everything was working perfect, except that the clutch was making a noise that’s the reason why I replace the compressor. My problem is that is not blowing cold air like it used too. With new compressor
    Any suggestions what could I have done wrong.

    1. Daniel,

      Thanks for your question your 2006 Town and Country. First, we would recommend putting a thermometer in your air vents to check and see what temperature the air is. The specification on most systems is between 34 and 40 degrees. If you’re getting warmer air than that, our first recommendation would be to bring your car back to the mechanic who did the work to have them check the pressures in the system and look over their work to see if there could be something they installed incorrectly. Checking the pressures in the system should give you a better idea what’s going on, but it’s possible that some foreign material got into the system while it was open to replace the parts which could cause a clog, or that the system is simply under charged with refrigerant.

      Thanks again for your question!
      -BD Auto Pro

    1. Todd,

      Thanks for your question about your 2006 Audi A6. Adding oil to your air conditioning system probably won’t quiet down a noisy compressor unless you recently had your system evacuated and didn’t have the correct amount of oil adding to your system when it was refilled with refrigerant, but even then it’s a long shot. Noisy compressors usually indicate an imbalance in the pump which or a problem with the magnetic clutch.

      Thanks again for your question!
      -BD Auto Pro

  5. I have a 1997 Oldsmobile Achieva and I’m changing the compressor and the Receiver Drier-Filter Drier.
    My question is along with putting the recommended oil and amount in the compressor itself do I need to put extra oil in the rest of the system also? Thank you

    1. Kenneth,

      Thanks for your question about your 1997 Oldsmobile Achieva. Air conditioning oil isn’t added specifically to the compressor. When you add oil to your air conditioning system you add it through the low-pressure port where it will mix with your refrigerant and travel through the system keeping the compressor lubricated. You can add the oil to your system using the BlueDevil Oil Injector you can find here:

      Thanks again for your question!
      -BD Auto Pro

  6. I’ve evacuated system with a recovery machine barely any oil came out of system. Just foam/ bubbles. Should I add oil when I recharge system n how much?

    1. Leo,

      Thanks for your question about your air conditioning system. That is a very difficult question to answer as it’s impossible to know how much oil came out entrained in the refrigerant. If you’re installing 100% new refrigerant that you know is completely free of any oil you might consider adding the manufacturer’s recommended amount of oil with the new refrigerant to make sure your compressor is safe. If you’re using recycled refrigerant, you may not need to add much oil as it may already have oil in it. Our best recommendation would be to contact a local dealership with your make of car and ask what their procedure is on an evacuate and refill.

      Thanks again for your question!
      -BD Auto Pro

    1. Malathy,

      If your air conditioning isn’t working and you’ve got a strange odor inside your car then it is possible that you’ve got a leak in your evaporator. It is the only component in your air conditioning system that is inside the cabin of your vehicle and your ventilation system blows air over the evaporator all the time so that could be where the smell is coming from. Try using Red Angel A/C Stop Leak and Conditioner (available here: to seal the leak and get your air conditioning working again.

      Thanks again for your question!
      -BD Auto Pro

  7. 1. Does refrigerant oil if a bit low effect cooling i.e.. if compressor requires 10 oz. of mineral oil and system has 6 oz. will this have any effect on cooling capabilities ?
    2. Can your red angel AC stop leak sealant 49496 be added to low side port without adding additional Freon if system has already been fully charged (using your oil injector to prevent future leaks)?

    Thank you and please send me an email if you answer these 2 question.

    1. Ben,

      Thanks for your question about refrigerant oil. Refrigerant oil usually does not impact the cooling capacity of the system unless there is so much oil it clogs the system or no oil so the compressor doesn’t work efficiently. Red Angel A/C Stop Leak can be added to a full system through the low side port using our Oil Injector which you can find here:

      Thanks again for your question!
      -BD Auto Pro

  8. Hi. On toyota Yaris 2004 model 1.3. I had compressor changed due to first one failing.

    The compressor i have is 5ser09c and takes nd8 oil and r134a gas.

    The problem I’m having with that is, A/C starts first time but when it cuts off at the right temperature inside the car, it doesn’t turn back on, until i switch the ac off and on. And sometime even switching it off and on doesn’t help.

    What problem could it be?


    1. Nouman,

      Thanks for your question about your Toyota Yaris. It sounds like you may have an electrical fault to your compressor, a problem with the compressor magnetic clutch or too much refrigerant in your system causing a high-pressure cutoff. First, try measuring the pressures around your system with it running to make sure you’ve got the right amount of refrigerant installed. If you’ve got the right amount of refrigerant, try checking the voltage at the AC compressor signal wire to make sure that the compressor is getting the run signal. If neither of those is the problem you may need to replace the clutch.

      Thanks again for your question!
      -BD Auto Pro

  9. Can I run my 1990 chevy Silverado with no oil in the air conditioner? I think it’s leaking oil and wanted to know if I can run it without using the air. Does it the pump still turn when I’m not calling for cold air or does it just spin on a clutch tell it’s called for?

    1. Tyler,

      Thanks for your question about your 1990 Silverado. When your air conditioning is switched off, the magnetic clutch isn’t engaged and your compressor does not sping so you can still drive your truck if you don’t have any oil or refrigerant in your air conditioning system. If your system is leaking oil, then it is also leaking refrigerant so we suggest using Red Angel A/C Stop leak to seal the system, then have your system completely evacuated and the correct amount of refrigerant and compressor oil added.

      Thanks again for your question!
      -BD Auto Pro

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