Wow. For 30 cents, I replace the orifice tube anytime the system is open, typically skipping the accumulator depending on the time frame of how long it's open. But that's not the problem. Fluctuation in pressure is, and that, you already know because you have a fan trying to pull down the high side.
Variable orifice tubes will do just as they are named, they will allow more or less refrigerant and oil to pass through and automatically adjust under certain pressure conditions. It's not an add on, it replaces the orifice tube.
The orifice tube is a filter and expansion valve in one little bitty piece.
Variable
The one you have
