Silly question

[duckman373]

If a sight glass is between the receiver and LL solenoid, shouldn't the sight glass be full when the solenoid closes? Why would it be empty?

[Russ57]

What makes you think it is empty?

[duckman373]

You can watch it drain after the LLSV shuts

[Russ57]

That would be before...or after the compressor stops?

[bunny]

Essentially you've got a finite volume (condenser, receiver and portion of liquid line) with some amount of refrigerant in it. For this to be 100% liquid, the refrigerant would need to be at a pressure that is equal to, or higher than the correspoding saturation temperature of the refrigerant.

When the compressor stops the liquid pressure reduces. Likely you're seeing the pressure fall below the point where the refrigerant would remain as 100% liquid.

[duckman373]

Essentially you've got a finite volume (condenser, receiver and portion of liquid line) with some amount of refrigerant in it. For this to be 100% liquid, the refrigerant would need to be at a pressure that is equal to, or higher than the correspoding saturation temperature of the refrigerant.

When the compressor stops the liquid pressure reduces. Likely you're seeing the pressure fall below the point where the refrigerant would remain as 100% liquid.

That makes sense. Thanks

[jpsmith1cm]

Either that or the liquid is physically draining back into the receiver, seeking it's own level as any liquid will tend to do.

This would depend on the piping orientation.

[Phase Loss]

Have you ruled out magic yet?

because I think it might be magic.

[cool_tech_llc]

I think it's the magic effect. But seriously, I see this all the time and agree w/ bunny & jpsmith1cm.
Worry about the site glass when box temp is close and the unit is running. Also pay close attention to SC and SH.