compressor icing up

[han81]

Hi all,
Dont usually look after fridge equipment but today looked at problem with coldroom. leak reported from condenser. System is a fosters and the condensing unit is mounted on side of coldroom in kitchen. System operates on r404, suction pressure 45psi and the room temp ok (4c) ,but found ice build up on suction and all over compressor. The leak is from ice melting when comp cuts out when set temp is reached. Suspected problem with refrigerant charge so reclaimed and weighed in correct charge from fresh cylinder - same problem.
Condenser coil is clean , both fans are operating and desired temp is being reached. Could anyone explain this ice build up and how to correct it? Also comp sounds quite loud during operation.
thanks
han

[mad fridgie]

Superheat is to low, liquid flood back.
Adjust TEV (or TEV could be faulty)

[monkey spanners]

What was the evaporator like, any ice buildup or fans not working?
Poor airflow or low load can cause liquid refrigerant at the compessor.

Is it a txv or capiliary system?

[mbc]

Icing up in compressor = liquid in there
Liquid in compressor =
1- Evaporator ice up ( needs defrost )
2- Fans not working
3 – Expansion valve is passing too much liquid (needs to adjust or might need to change )

[mafoi]

Why Evap ice up can cause flooding if TXV is OK? Isn't Evap superheat controlled by TXV? Is that because the compressor can't unload further?

[monkey spanners]

Mafoi,

TXV's can only shut so far, maybe down to 25% or so. If there is not enough load, that 25% can be enough to cause liquid to return to the compressor.

But ice on the compressor does not mean there is liquid returning to it, you would need to measure the superheat to know what is going on.

e.g. if the system is evaporating at -40c you could have a compressor inlet temperature of -30c without any liquid there, or it could be evaporating at -30c and have a compressor inlet temp of -30c also and have liquid returning. We need to take some temperature and pressure readings to know what is really going on in a system :)

Jon

[lowcool]

if you have a suction/liquid line heat exchanger fitted to the coil it is possible that it has split internally

[mafoi]

Thank you for the reply on TXV. I thought TXV can shut it self down all the way to close.

Anybody can help with the question on relationship between iced evap coil and compressor flooding?

Thanks a lot.

[mbc]

Dear spanners
you right
but he put on suction and all over compressor is ice.
So ice in the over compressor it means liquid in suction line.