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AC Question?

I recently acquired a new (used) AC system for my house.  Mitsubishi mini-split system with 2 zones.

It has been stored in a storage unit for about the last year, unfortunately the ends were NOT sealed off when removed.

How can I test it to make sure it works before installation?  I have heard these systems are very sensitive to water even in the air....

I would like to make sure it works before installation as it will be quite a process....

What are my options?

Thanks in advance!! 


  • McGee
    McGee Member Posts: 14

    I did that once and never again. It may have poe oil which is very hygroscopic( easily absorbs water). The one I did lasted for less than a month before the compressor locked up. If you do decide to go for it I would at least change the oil. Good luck
  • Spence
    Spence Member Posts: 316
    Testing Opened System

    R-410A oil is a sponge, if that hints at what you're up against. The sections that were open to the atmosphere will have to be purged with nitrogen, then triple evacuated with more nitro in between. You most likely will never get out all of the moisture; have your factory tech rep recommend an oversized liquid line drier as well.

    Since you're most likely able to float a boat with the moisture, try to get your triple evacuation to 300 microns or below. If you can't, here's a guideline: after each evac, change your pump oil. If you can get to 500 microns, for example, and you don't rise over 750 within a minute or two, you're probably at the best you can get under the circumstances.

    Please understand this is not without risk. The system has to be hooked up to do this, or you'll be doing 9 evacuations. And the system may not run or live long anyway. If it does run