Mini split service valve question

Old 04-18-19, 11:52 PM
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Mini split service valve question

I got a new mini split (R410a) that has not yet been installed. I was just doing some initial checks on the unit. I opened the service valve port cap and heard a slight hiss, as if the cap was under pressure.

Why would its cap be under pressure? Doesn't make sense to me. Any thoughts?

Secondly, can I check the system pressure using a manifold gauge with the valve backseated or does the valve need to be opened fully to check the refrigerant charge? I just want to check if the unit has adequate refrigerant in it, before getting it installed.

Last edited by whiteangel; 04-19-19 at 12:26 AM.
Old 04-19-19, 03:52 AM
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You can not detrermine the refrigerant charge without the unit connected and running.
Your installer will figure that out.
That hiss you heard will be removing refrigerant.......don't do that!

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