Hi Gents,

I've heard that sight glass shall not be used to inspect refrigerant charge level in refrigeration systems using R134a. The reason is that R134a provides a false indication that the system is underchanged (bubbles) - when in fact it is not - leading to a refrigerant overcharge of the system.
In this case, the only way to verify system charge would be using a set of manometers at low and high pressure side ports.

Thanks and Merry Christmas !!