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I just finished installing my first mini split system and until now things have been a breeze. It's a pre charged unit. Hooked up lines pulled a vacuum, waited to check for leaks, released some coolant, waited some more to check for leaks, released the rest, more leak checks (there never were any), then disconnected the vacuum pump. When I disconnected the pump from the service port refrigerant and oil sprayed down my arm, a lot more than the little puff I was expecting. Is that normal/acceptable? What should be my next step to verify that things are ok?
 

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It’s a precharged unit as in the refrigerant lines were precharged?
You don’t check for leaks with refrigerant. That’s done via a nitrogen pressure test and measuring the micron level of the evacuation.
The vacuum pump shouldn’t have been connected to a pressurized port.
 

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Not sure what you mean when you said you released the charge and then removed the vacuum pump. Depending on how you did it, the system could have sucked some of the oil out of the vacuum pump and into the system, and then all over your arm somehow.

This isn't a good thing since the oil that's in the vacuum pump isn't compatible with the oil that's in the refrigeration compressor.

Either way, if you lost enough of the refrigerant charge to effect it's performance, the only proper way to deal with it is to recover what's in there, and then weigh the proper amount back into the system.
 

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It sounds like you had the vacuum pump shut off at your gauge manifold with no shutoff valve at the hose end. When you released the charge, you pressurized the hose. When disconnected the charging hose, you lost whatever amount of refrigerant and oil that was in the hose. I wouldn't worry about it for now... you probably didn't lose enough to affect the performance.

Next time get and use a disconnect valve on the charging hose end. Shut it off before releasing the system charge and you will avoid the problem you had.
 
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