I installed a 5 ton water to water heat pump..
Told by manufacturer that it holds 68 oz, of 410.
Emptied it,put vacuum to it and filled it with 68 oz.(weighed the tank).
Its heating great but only for 30-45 minutes it shuts down.
When running there is nothing visible in the sight glass;no liquid,no bubbles nothing....
Should there be liquid visible ,if so,what should it look like?