DX System Help

[HVACRSA]

I need some help diagnosing a built up DX system -

The system is running a Bitzer Semi Hermetic Compressor, liquid line splits into two seperate evaporator coils each has its own TXV and Solenoid control on the liquid line, system is running on R407c and air cooled condenser coil.

Does one calculate super heat the same way as you would on a single TXV system?
Oil in compressor is 'bubbling' or 'frothing' like crazy, is the best place to start diagnosis by check Super heat and Sub cooling?
Suction Pressure is constantly hunting...

Any advice would be appreciated.

[passandscore]

You are on the right path! Check the superheat on each evaporator, the method is always the same. You may very well have one or both TXVs flooding back slightly.

[Brian_UK]

Is there a good solid supply of liquid to both TxvS?

[monkey spanners]

Are there check valves at the exit of the two evaporators? Are the two evaporators running at the same temperature? (if not refrigerant can condense in the cooler one when its off and the warmer one is running.)