If an AC system is designed to keep liquid refrigerant out of the compressor, will the compressor be ok if installed upside down? It should only be dealing with gaseous refrigerant, but I don't know if there is something in the pump design where orientation matters. I know if you invert something like a complete window AC unit and try to run it, things will go boom when liquid hits the pump.

3 Answers 3


No, a typical fixed-use AC compressor will NOT work properly in any orientation but upright.

Most designed have a sealed can containing the compressor itself with an electric motor driving a crankshaft to which a connecting rod is attached which drives the pump. The bottom of the can is filled with lubricating oil for the bearings on the shaft and connecting rod.

If you invert the unit the oil will go to what is normally the top of the can and will not lubricate the mechanicals properly.

Here is a diagram that shows the basic layout of the parts:

AC compressor diagram


That may vary by compressor. As such, the matter is decided by the labeling, instructions and data sheet for that particular compressor.

If it connects to mains power, this is called out in NEC 110.3(B) and obviously, misapplication will void the warranty.

  • Do you have such an example?
    – Pilothead
    Commented Jan 26, 2020 at 4:35

That will also depend on the design of the compressor - on my car the compressor is the lowest point...

  • Hi. This doesn't answer the question; it's more of a comment. Commented Jan 25, 2020 at 18:18
  • @DanielGriscom if one knows refrigeration there is a lot in that answer, if one does not it then looks simple :)
    – Solar Mike
    Commented Jan 25, 2020 at 18:45
  • 1
    does that requirements not make it a useless answer?
    – Jasen
    Commented Jan 25, 2020 at 22:45
  • @Jasen sorry grammar errors confuse...
    – Solar Mike
    Commented Jan 25, 2020 at 22:47

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