Lt pack freezing back

[brody19]

Greetings

i have an lt pack with 7 compressor, but one is constantly frosting back badly.
Every other comp is ok,all off a common suction line.
Superheat is ok,evaps and akv's also ok.
Now, i'm told this compressor has been changed, but as soon as the suction service is opened, you can see the oil bubbling.
I think the suction side of this compressor is passing, but any other ideas would be of great help

cheers
9430

[monkey spanners]

I don't work on packs generally. Seems to me you're only going to get that much frost from evaporating liquid, if the other comps on the common suction are not frosting (unless the piping is not distributing evenly) then it must be getting liquid from somewhere else,

Oil level doodad?
Liquid injection solenoid etc stuck open?

Think i would put some gauges on and have a play at shutting suction/discharge etc valves to see if the pressure went up with the compressor isolated, (and not running) then decide what would cause what i'm seeing.

[install monkey]

oil seperator leaking ?

[Rob White]

The insulated pipe feeding to the side is saturated vapour / liquid
and is used to cool the compressor down. Close that down for about
20 mins and see if the frosting stops.

Regards

Rob

.

[Tayters]

Looking at the photo the frosting isn't coming from the suction pipe (although it looks like the rotalok is shut).

I've seen the same result on Space packs with Temprite oil seperators. The O ring at the bottom of the filter distorts. Think this was letting some refrigerant through which then ended up condensing along the oil line. If one of the oil management systems is open then off you go. To prove the point can you shut down the oil line to that compressor.

If you want to check the O ring I think the only way is to open it up and have a look, but with the packs mentioned it seemed a common fault. Used to replace the filter at the same time, add a bit of oil if you fancy to the lower level if there was doubts there was enough in the first place.

Also if the oil seperator doesn't seem to keep any oil in then this can be caused by the lower O ring messing up.

Cheers,
Andy.

[install monkey]

question is did the 1st comp sieze or get changed because of they thought valves were passing on a scroll comp??:D

[THE DUDE]

Check the Desuperheating valve ( if it has one). You said the superheat is ok, I have seen floodback fall into a suction line on a compressor that wasnt running. The gas/liquid was getting pulled across the suction line and liquid was falling down into the compressor. Anyway you need to correct this ASAP. The Liquid in the bottom of the Compressor washes off the Bottom Berring very quickly! I am curious to see what you find out...Best of Luck.

[cold.man]

Looks like its on a project first pack for Tesco?.
what super heat are you getting on the cases on the shop floor?
Found this happening before due to superheat being set to low on a few cases on the shop floor.

[brody19]

Thanks for the advice. Will have a play with it and let you know

[lv frigo]

Hi!
From the picture it can be concluded that the refrigerant comes through the oil level regulator. Have you replaced the oil level regulator? Do you have a heater in the oil separator and the oil receiver?

Good luck

[padraic]

shut hand valve to emerson oil float and if it stops replace it... had the same problem before and when the compressor was off it was still passing and filling compressor