Originally Posted by BURL-REF
For a long line set application, with the liquid line and evaporator above the condenser, it is best to have a LL solenoid at the outdoor unit to prevent liquid draining back into the condenser and displacing the vapor in the condenser coil.
Originally Posted by Snapperhead
If the condenser coil and discharge line are full of liquid when the compressor starts, there will be a huge spike in the head pressure for a short time, sometimes even rather violent vibrations. I've seen trip discharge line mounted high pressure switches, and cause cracks in the discharge line due to the vibration.
Scroll compressors sound especially angry starting under those conditions.
A non bleed TXV will take care of things at the evaporator coil end of the lines.
Yes, this scroll was certainly pissed off by all the liquid. It scared the crap out of me, I left the system off until the solenoid was installed. Now it works like a charm
Here is a PDF on the issue from Carrier.