Low condensing pressure on freezer, not pulling temp

[Crypton]

I have a walkin freezer room thats not pulling temp. Got a call last night, freezer was at 3.2C. by the time I got there it was at -13.8. Checked out system. Everything seemed ok. sight glass full. discharge pipe roasting,suction pipe cold,liquid warm, condenser coil clean,evap coil clean. All fans running. Suction pressure 2bar,condensing pressure 11bar. Very little heat rejection from the condenser. Blocked the condenser coil pressure slowly rose to 17.5bar. unit pumped down slowly as well. Condensing unit is Maneurop. Compressor is a NTZ068A4LR1A. Would I be right to say compressor is on its way out? If compressor is gone would I be right in changing it to a Copeland scroll?? Thanks for any help

[cool runings]

I have a walkin freezer room thats not pulling temp. Got a call last night, freezer was at 3.2C. by the time I got there it was at -13.8. Checked out system. Everything seemed ok. sight glass full. discharge pipe roasting,suction pipe cold,liquid warm, condenser coil clean,evap coil clean. All fans running. Suction pressure 2bar,condensing pressure 11bar. Very little heat rejection from the condenser. Blocked the condenser coil pressure slowly rose to 17.5bar. unit pumped down slowly as well. Condensing unit is Maneurop. Compressor is a NTZ068A4LR1A. Would I be right to say compressor is on its way out? If compressor is gone would I be right in changing it to a Copeland scroll?? Thanks for any help


You don't mention the type of refrigerant?
It is important so we can make a jugement on the comp.

Have you done a pump test on the thing.

With gauges fitted front seat the suction service valve and see with the suction does.

It should go very low into a vac (lower than 15"hg about 20"hg to 30"hg), the lower the better and with the
comp off it should stay like that for a good few mins (you may need to do somthing to the lp
switch to allow it to pump into a vac).

coolrunnings

.

[Magoo]

TEV are designed for a certain pressure drop across the vav to feed liquid to the evaporator, reduce the delta p and you starve the evaporator.

[Tankerbox]

the ultimate question!
what is your subcoolin, SC and superheat. SH?
its a must check.

[flyinkiwi]

Hope you've found the cause of your problem.

Slow pump down sounds like you might have an issue with valves in the comp. Like Cool Runnings said - do the pump-down test.

If you fit a scroll as a replacement, you may find you have to install other fun stuff like liquid injection for cooling - might make replacing the manuerop with an identical unit more attractive.

[lana]

Check the refrigerant amount.

If the compressor head is roasting then you have very high compression ratio.
Probably there is not enough gas in the system.
Cheers

[Crypton]

Thanks for the replies. Did the pump down test and the unit barely made it into a vac. Turned off compressor and it never held. It came straight out. I changed the compressor for a copeland scroll with liquid injection. Ran up the compressor and it pulled -19 in no time. Thanks for your help.