How do I Add AC Compressor Oil?


You probably don’t often think about how your air conditioning system makes cool air on a hot day.  That is, until your car air conditioner is blowing hot air and you’re left arriving at your destination with the sweaty imprint of where your seat belt crosses your shirt.  It really is a relatively simple concept that causes your air conditioning system to work, but it requires a few unique pieces of equipment to work properly in your car.

How does my car A/C work?

Most refrigeration systems, including the air conditioner in your car, work on the simple principle that as a gas expands its temperature drops, scientifically called the Joule-Thompson effect.  You’ve probably seen this in effect if you have ever used a CO2 fire extinguisher.  As the gas is released, the remaining CO2 in the extinguisher can expand, causing the fire extinguisher to cool off.  The opposite is also true.  As a gas is compressed, it will heat up.  This is the same principle that causes a diesel engine to work, and can even be seen when using a bicycle pump to inflate a tire.  Notice the pump and the hose will get hot partly due to the compression of the air.

The refrigerant in your air conditioning system gets compressed by your AC compressor where it also heats up.  It then is cooled back to atmospheric temperature in the condenser at the front of your vehicle.  The atmospheric refrigerant is then allowed to expand through an expansion valve or orifice tube.  This expansion causes the refrigerant to cool below atmospheric temperature where it then travels to the evaporator which is inside the cabin of your vehicle.  Cabin air is passed over the evaporator, causing the air to cool and the refrigerant to return to atmospheric temperature.  From there it returns to the compressor to start the process again.

Your air conditioning compressor is the only moving piece in your air conditioning system but without it, the process wouldn’t be possible.  The air conditioner compressor is usually mounted on the front of the engine block where it can be turned by a belt on the engine.  The compressor has a pulley and clutch assembly on the front to allow the belt to always be attached to the engine, and to also allow the compressor to engage and disengage with the clutch.  The RPM your engine is turning, and the amount of cooling load on your air conditioning system will determine how often the compressor is engaged or disengaged.

How do I prevent my A/C blowing hot air?

Cycling your AC compressor on and off like this unfortunately adds a lot of wear and tear.  It also functions in a very high pressure system through a variety of temperatures and has to live in an environment that is constantly vibrating and sustaining impacts from your engine running and your car driving down bumpy roads.  This is a difficult life for any pump or compressor so it’s important to take care of your AC compressor.

The best way to ensure the long life of your AC compressor is to ensure that you add adequate oil any time you add refrigerant to your system.  If you’ve discovered a need for more refrigerant in your vehicle, add BlueDevil Red Angel One Shot.  Red Angel One Shot has the correct proportion of refrigerant and an advanced leak sealing agent that works as a lubricant until there is a leak.  If you have evacuated your air conditioning system, use BlueDevil’s Red Angel Oil injector to add Red Angel A/C Stop Leak to your system, ensuring lubrication and leak protection for your vehicle’s air conditioning system.

BlueDevil Products can be found on or at AutoZone, Advance Auto Parts, O’Reilly Auto Parts, NAPA, and other major auto parts retailers.

24 responses to "How do I Add AC Compressor Oil?"


  1. allen on October 16, 2014 at 10:40 pm

    I am wanting to add oil to my ac compressor without taking off the compressor.. is this possible? its on a 2002 trailblazer

  2. SLS on April 23, 2015 at 2:00 am

    I have had my system recharged twice and after each time the next day my system is blowing hot air I have also replaced the lower and high side ports, still after being charged the feon is leaking out should the compressor oil and stop leak be added to my system

    • BlueDevil Pro on May 4, 2015 at 10:42 am


      Yes, we recommend adding 1 can of the Red Angel A/C Stop Leak through the low side service port. After adding the Red Angel you should then recharge the A/C system to its proper level.

      Thank You!


  3. Alfredo on May 4, 2015 at 7:18 pm

    I have a 2005 Honda Odyssey and has the compressor replaced and the ac lasted one day and then it just blow hot air. I had the mechanic where they added more freon but never checked the oil for the compressor. Is this the problem?

    • BlueDevil Pro on May 5, 2015 at 4:25 pm


      Thanks for your question about your Odyssey. It doesn’t sound like your problem is a lack of oil in your air conditioning system. Most air conditioning systems only use about an ounce of oil while they use significantly more refrigerant. Even without oil, your system should continue to run for longer than a day. If your compressor needed to be replaced it is possible that it allowed debris into the lines of your system when it failed causing a clog. Your mechanic should be able to use a set of AC gauges to determine if there is a clog and which other components should be replaced.

  4. Raman on June 18, 2015 at 2:03 am

    My 2005 Dodge Grand Caravan v6, 3.8 slowly stopped cooling. Local auto store checked the freeon level, which came as low. They suggested to add more freon. Today i end up adding the whole canister and level barely increased. Then I found big puddle of oil leak under the car. I restarted the car and it was working fine, motor and transmission oil was fine. I turned the Ac on and more oil started coming. Any idea what may have happened? Or what should I do?

    • BlueDevil Pro on July 6, 2015 at 12:23 pm


      The problem you are describing is kind of confusing. Your air conditioning system does use oil to make sure things stay lubricated and operating properly but it is a very small amount, maybe 2-4 ounces total. It is possible if you’ve been adding refrigerant with oil in it regularly, your system may be over filled with oil. The refrigerant in your AC system is a gas at room temperature so the puddle is certainly not made of refrigerant. If your AC system is over filled with oil you can have it evacuated and refilled with new refrigerant to clean it out.

      The other possibility is that turning your air conditioning on is putting enough stress or torque on some component on your motor it is causing it to leak. To help you identify what your van is leaking, check out this article about how to identify what your car is leaking:



      • SRG on July 30, 2015 at 6:46 pm

        I have a 2005 Town and Country with the same problem. My leak is just forward of the passenger side rear wheel well. There are two hoses and now one leaks an oil that is clear and has no odor. The hoses (lines) are attached to metal lines that run to the front of the vehicle and appear to go to the A/C unit. I’m thinking it’s “PAG 46” (?) but I have no idea of how to recharge the lines after I replace the hoses/connections. My A/C still works but I have bled more oil than I am comfortable. Can you help?

        • BlueDevil Pro on August 10, 2015 at 10:45 am


          Thanks for your question about your Town and Country. It is difficult for us to diagnose the problem that you’re having with your van. Since R-134a is very volatile, if your system had a big enough hole to leak the oil, it would be very low on refrigerant as well and very soon not work properly. You are correct that you can use PAG 46 oil in your system but we wouldn’t recommend adding any oil until you are sure of what the leak is. It is possible that you simply have condensation on your AC lines under your car and it collects oily residue from under your car as you drive.

          Thank You!


  5. Ed on June 27, 2015 at 1:20 pm

    I’m about to add some R134a with dye refrigerant to my 2001 Toyota RAV4 because its cooling has been noticeably decreased last year and especially this year ( assuming no major leakage, otherwise would expect no cooling at all). I’ve owned this vehicle for 8 years now. My two question are: 1)Does losing R134a also mean the lubricant is lost (wouldn’t expect oily, non volatile lubricant to be lost). 2) In a situation such as mine, how does one tell if lubricant should be added (realizing too much lubricant in air conditioner is bad too)
    Thanks, Ed

    • BlueDevil Pro on July 6, 2015 at 1:47 pm


      Unfortunately there is no way to tell if you have the proper amount of oil in your air conditioning system. The correct way to fix it is to completely evacuate your system down to a vacuum then recharge it with the manufacturer’s specified amount of refrigerant and add the recommended amount of oil.

      If your leak is small, it is very unlikely that you’ve lost any oil as the R-134a, like you said, is much more volatile. If you did loose oil you would probably be able to see the residue around the leak point after you add the dye. With a small leak, you should be fine simply adding BlueDevil Red Angel AC Stop Leak (available here: and then recharging the system to the proper pressure with R-134a.

      Thank You!


  6. Darrian on June 29, 2015 at 4:09 am

    Working on a 2009 dodge caliber—
    I replaced the ac compressor and filled the freon it ran cool for about 5 mins then the freon purged out and keeps purging after i fill it. Any sugestions

    • BlueDevil Pro on July 6, 2015 at 1:52 pm


      Thanks for your question about your 2009 Dodge Caliber. It sounds like you have a leak somewhere in your system where the new refrigerant you are installing is leaking out. Before you add more refrigerant, use BlueDevil Red Angel AC Stop Leak (available here: to seal your leak so your system will stop loosing refrigerant. Once the leak is sealed you should be able to add refrigerant to the proper pressures and get your system back to working like normal.


  7. carl on July 9, 2015 at 3:11 pm

    I installed an AC compressor in my car.
    First time I had ever done something like this.
    But, I did not add oil.
    Charged it and its cool and quiet.
    Now I am worried that I should have added oil.
    Lot of work to pull the Compressor.
    Can I add oil now that the Compressor is already on my car?

    • BlueDevil Pro on July 9, 2015 at 8:41 pm


      Thanks for your question, and great job changing out the AC compressor and getting it to work properly. If your system simply had a slow leak and you never had it professionally evacuated then it is possible there is still plenty of oil residue in the system to work right. It is impossible to tell how much oil is in your AC system, but if it was evacuated before you put the new compressor on then you should probably add some oil. You can use the BlueDevil oil injector (available here: to add oil even after your system is filled. You should be able to get oil and the amount you should add from your dealer.

  8. Andrew on August 11, 2015 at 7:26 am

    I replaced my compressor which appeared to be dry. I added a can a oil first. I then added the refrigerant. After several days of driving, when I turned on the air. the engine would sputter like something was hindering it. Is it possible that there is not enough oil, or is the compressor beginning to fail internally?

    • BlueDevil Pro on August 20, 2015 at 5:21 pm


      Thanks for your question about your air conditioning. It is possible that your compressor is failing if it is hard enough to turn that it is trying to stall your engine. The other possibility is that you added too much oil to your system. Refrigerant is a gas or light liquid in your air conditioning system so if you added too much oil it is possible the compressor is struggling to move that much oil. You can try calling a dealership to find out how much oil your car’s AC takes but in most cases it is just a few ounces. If you did over fill your system with oil you will need to have it completely evacuated before you try filling it with the correct amount of oil and refrigerant.

  9. Kobe on August 24, 2015 at 2:36 pm

    I have dogde caliber ac full service all parts of ac system is all new . But my problem the new ac compressor oil enough or need to add more oil?

    • BlueDevil Pro on August 26, 2015 at 1:15 pm


      Thank you for asking about your Dodge Caliber. You should first check the oil to see if you are at capacity or not. If you are low, then we would recommend adding oil. Feel free to contact our technical support line at 888-863-0426 with any other questions.

      Thank you!


  10. Ryan on September 1, 2015 at 3:15 pm

    I recently replaced the harmonic balancer on my car. I was breaking serperntine belts and did determine that the balancer was shot. After replacing the balancer, the car began to sputter and then the AC quit. There is now oil all over the pulley attached to the AC condenser. There was some periodic sputtering that occurred even before the harmonic balance went out. Could a problem with the AC compressor lead to problems with balancer? They are located in line and very close to one another. Or, could the failure of the balancer have caused a failure with the compressor? Is my compressor shot now that the oil leaked out (based on the location of the leak, I assume leaked from the shaft seal). For what it’s worth, now that the oil blew out of the compressor, the engine sputtering has also stopped. I have never added oil or recharged the AC system in any way, so being overfilled was not the problem.

    • BlueDevil Pro on September 15, 2015 at 2:24 pm


      If your harmonic balancer was bad it wouldn’t be surprising if it also destroyed your front crankshaft oil seal as well. Also, oil leaking onto your AC compressor could possibly damage it, but for the most part, your compressor is a sealed unit and shouldn’t be damaged by a little oil spray. It is possible that whichever of the components went bad first it was part of premature wear and failure of the other. If your vehicle is running correctly after your AC failed then it is an indication that your AC compressor has mechanically failed and was putting excessive load on your engine causing it to run poorly like you mentioned.

      Since things are runny properly with the new balancer, our recommendation would be the replace the AC compressor as well and have your system recharged to see if you can get things back to normal.

      Thanks again for your question!
      -BD Auto Pro

  11. Mentor Hasani on September 6, 2015 at 3:08 pm

    Hi, I’ve got a Nissan Quest 2005 and it was making somekind of screeching sound when started and it’d go away after taking off. A friend sugested that air compressor is makind that sound and need oil, thus I added oil to it and the sound went away but now I’ve got another problem, the compressor runs ans stop while driving causing to blow hot air more than cold air.
    What should I do, do you think I need to put more refrigerant?

    • BlueDevil Pro on September 23, 2015 at 4:45 pm


      Thanks for your question about your Nissan Quest. Great job adding compressor oil and getting the screeching to stop. The screeching may also have been an indication of a belt issue so you may consider replacing your belt as well. The compressor will normally cycle on and off while you’re driving to keep pressures where they should be in your air conditioning system. If you’re getting hot air, we would recommend checking your refrigerant levels as well. If you find a low level, use BlueDevil Red Angel AC Stop Leak (available here: to seal the leak causing the low level, then putting more refrigerant in.

      Thanks again for your question!
      -BD Auto Pro

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