Profroid MiniCO2OLcompact Notice D'instructions page 66

10 TROUBLESHOOTING
Examples of failures – list of solutions is not exhaustive
DEFAULT POSSIBLE ROOT CAUSE
1. Too high Suction Excessive superheat LT or /and MT.
LT discharge temperature too high.
temperature (MT or LT)
Temperature sensors not enough tightened or wrongly
positioned
Not enough refrigerant charge
2. Too low LT or MT Liquid in suction line.
suction temperature
Too high liquid level in the receiver
Sensor loose or incorrectly positioned
3. LT or MT suction
Too much oil in the evaporators.
pressure too low
Filter dryers clogged
Suction filter clogged
Excessive superheat at suction side
Too low pressure into medium pressure vessel
Not enough refrigerant inside the installation.
4. Compressors stop too See point 3
often due to low
Control system parameters not adjusted
pressure switch cut out
Evaporator frozen or water inside the
distributor
5. LT or MT suction For MT : MP valves blocked open
pressure too high
HP valve leaky or drive defective
End of defrost
Compression problem on compressors
6. Too high pressure Insufficient airflow to the condenser / Gas Cooler.
for condenser /gas
cooler
HP Valve Closed
Sensor Defective / incorrect set point
Installation overfilled with refrigerant.
Air or gas non condensable in the high pressure side
7. Too low pressure into Abnormal air conditions
condenser/gas cooler HP valve open blocked
8. LT and MT discharge Excessive superheat at suction side.
temperature too high
Internal compressor bypass. See section 1
Expansion device (liquid into suction line).
9. Oil foaming at
compressor restart
Sensor loose or incorrectly positioned
Crankcase heater out of order.
REPAIR
Inspect and adjust evaporator electronic expansion valves
Insufficient load on MT rack
Check operation of the AKV pressure regulator
Check and replace the sensors on the suction line, if
necessary.
See section 6.1.7
Adjust electronic evaporator expansion valves.
Remove excess of refrigerant
See section 6.1.7
Check and replace the sensors on the suction line if
necessary.
Drain evaporators
Check oil separator efficiency
Check and replace filter dryers.
Check suction filter
Adjust electronic expansion device
Check MP and HP valve operation
Add refrigerant into the installation.
Check parameters
Clean and defrost evaporators
Reset MP valve (switch off-on)
Check position of the gas gooler outlet temperature sensor
Check HP valve tightness
Gas cooler sensor defective
Wait for confirmation
Check valves plates and gaskets.
Clean Condenser / gas cooler check fans. Check any
ventilation or air recycling issue.
Check
Check
Remove liquid from the MP vessel.
Evacuate the air at the highest point
Check and adjust
Check the control parameters
Adjust expansion valves
Check valves plates and gaskets
Check the evaporator expansion valves.
Check position
Replace the heater