Carrier Global

[Bash1803]

Any Carrier gurus?

Got a 30GX that was tripping on LP shortly after startup. Done a leak repair as it was around 50% short.

Commisioning it and it still trips on LP shortly after start. Liquid line glass is full then drains rapidly shortly before tripping.

EXV tests ok. Could be an oil logging problem? Any ideas?

Thanks in advance, Bash

[Grizzly]

Blocked Liquid line filter Maybe?
Just a thought.
Or if it has one Liquid line solenoid / coil us?

Grizzly

[Bash1803]

Thanks Grizzly,
Driers were replaced during repair and lifters were put on coils, but coils ok in any event.

[Grizzly]

Ok.
Thanks for replying and over to some of our carrier specialists!
Grizzly

[Supernova86]

Seen a few 30GX's do this.
If they run unloaded they can dump their oil charge.
Had two which had oil laden liquid lines causing circuits to trip on low evap temp.
Even took at EXV ( old type flanged top ) apart before and found it full of oil.

[Grizzly]

Top answer supernova,
Rep point added.
Grizzly

[Bash1803]

Thanks guys, kind of confirms what I was thinking in terms of oil logging, wasn't sure if in liquid line or excess sitting on top of evaporator liquid level. Unfortunately evaporation level switch is digital input rather than analogue, so can't work out the level in evaporator - do you think connecting hoses with a sight glass in between to measure liquid level in evaporator would be worthwhile?

[Bash1803]

Plus, if exv was blocked, surely the sight glass on the liquid line would remain full, it wouldn't empty. Additionally, when the system goes out on LP the Evap pressure sensor reads 0kPa on the Prodialog, keeping this in mind I don't think the high side can take the entire refrigerant charge as the evaporator is flooded - plus it happens quickly after start up, would take time to drain the evaporator completely....

[Supernova86]

I'm sure there is no liquid in the evap if it is tripping that quickly after start up.
Does the LP come back up after it trips?
I would double check the evap transducer is calibrated.
All there is before the EXV is two service valves, drier cores and a solenoid valve ( if we talking about the same air cooled 30GX )
Have never seen a liquid level on a 30GX, only oil level switch.

Ian

[Gibbo]

I'm sure there is no liquid in the evap if it is tripping that quickly after start up.
Does the LP come back up after it trips?
I would double check the evap transducer is calibrated.
All there is before the EXV is two service valves, drier cores and a solenoid valve ( if we talking about the same air cooled 30GX )
Have never seen a liquid level on a 30GX, only oil level switch.

Ian

The chiller is a phase 2 Pro Dialog with a black display. screen
The liquid level is likely to be very low on start up in the cooler. Circuit will do a pump down on start up hence the clear sight glass, the liquid in sight glass suddenly draiming quickly would indicate exv opening.. It could be the refrigerant has migrated due to the low temp ambients or as mentioned if low load or short cycling the oil will leave the oil separator. I would monitor exv position ,cooler liquid level and discharge superheat on start up.
Gibbo

[Bash1803]

The chiller is a phase 2 Pro Dialog with a black display. screen
The liquid level is likely to be very low on start up in the cooler. Circuit will do a pump down on start up hence the clear sight glass, the liquid in sight glass suddenly draiming quickly would indicate exv opening.. It could be the refrigerant has migrated due to the low temp ambients or as mentioned if low load or short cycling the oil will leave the oil separator. I would monitor exv position ,cooler liquid level and discharge superheat on start up.
Gibbo

Gibbo, thanks very much for your reply. Have you had experience of a similar situation?

[Bash1803]

Thanks for the advice lads. Just to let you know, it's sorted; oil logged cooler. Running like a dream now.