My car AC has been dead for a couple of years now and I was wondering the following things:

  • How could that affect the AC oil level?
  • Is there anything I should be worried about considering my AC system has been idle for a few years
  • How can I figure out if there is any oil missing?
  • How can I figure out how much extra oil to add if any is needed?
  • No way to check the amount. Unless you had a leak and leaked the oil out while running it still has the proper amount of oil.
    – Moab
    Commented May 10, 2020 at 15:31
  • Awesome @Moab, so I should be ok then. Is there any point doing such a test to at least making sure there is oil in there: youtube.com/watch?v=uI5x7VPpvVY Commented May 10, 2020 at 15:38
  • Oil circulates though the entire system, so no way to measure it. There might be a way to indicate there is oil present but will not indicate how much is in the system. When in doubt add 2 ounces.
    – Moab
    Commented May 11, 2020 at 15:40
  • Maybe pertinent is the age of the car. I had an old BMW735iSE where the aircon would only run when the button was pressed. All well and good, I thought, who needs aircon in winter. Little did I know that letting it sit idle for 6 months would mean the seals ripped themselves to shreds next time I used it. My brother in law, an aircon service engineer, pointed out my dumb mistake. My current much newer Merc doesn’t let this pump idle, it spins it up itself to prevent this damage.
    – Tetsujin
    Commented Feb 14, 2022 at 16:04

1 Answer 1


Checking oil as described in the video can only be done when the a/c system remains sealed and can maintain vacuum. Your other question presumably about the same vehicle indicates the a/c system does leak.

A leaky a/c system loses vacuum and becomes inoperable. Because the system is now empty (two years is a long time), you cannot assess its oil level using the method demonstrated in the video.

  • Also if the vehicle has been sitting s long period of time without a charge, air and moisture has been introduced and moisture will damage A.C. components. The accumulator\drier would have to be replaced the pump may have some internal corrosion. It should have all necessary parts replaced, the system flushed. After the system is flushed a professional will know how much oil to install. Each component requires a specified amount of oil.
    – Jupiter
    Commented May 10, 2020 at 22:26
  • David, yes that is the same vehicle. I am aware the system must be leaking, but I am not sure what it means in term of oil level and how to top it up. Commented May 11, 2020 at 7:55
  • @Jupiter, it sounds like the entire system is good to replace. Are you saying I should anyway, no matter what, flush the oil from the system as some of it will be missing (and while I'm at it, check all the AC components)? Also, should vacuuming the system not be good enough to remove all the moisture from the system? Why would the accumulator need replacement? Thanks Commented May 11, 2020 at 7:58
  • An accumalator driers purpose is to remove any moisture in the system. If it is exposed to air (which it will be in an uncharged system) it will be exposed to the moisture in the air. This same moisture can contaminate every other component causing corrosion. If you want risk free AC, everything should be flushed to start with a clean system. At the point you are at now it would be best for the pros. Proceed on your own if you like, but my rule to myself is: if I work on my A.C. without the right equipment, don't cry to myself when it don't work.
    – Jupiter
    Commented May 11, 2020 at 13:26
  • Vacuuming will remove all the moisture but cannot repair the accumalator drier and cannot repair the damage that the moisture created.
    – Jupiter
    Commented May 11, 2020 at 13:31

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .