Troubleshooting

Strongly fluctuating operating conditions

High evaporator capacity in relation to compressor capacity + high degree of start opening of the electronic expansion valves.

Reduce the start opening.

Control of the optimum high pressure.

Control of the gas cooler fans: In operation up to a minimum temperature, temperature sensor not close enough to the outlet (PT1 dead timer), or incorrect position (correct 5 or 7 o'clock).

Parameters for controlling the suction pressure.

Assess neutral band and time delay, assess actual and required load, make small changes only incrementally and then reassess.

Large change in capacity per stage of capacity control.

In the field: Check parameter settings for more stable operation, e.g. higher min. pressure in gas cooler.
During planning: Increase the number of compressors, change the displacement of the guide compressor.

Application limit is not respected

Operation too close to the application limit and overshooting the control.

Adjust PID control (Proportional-Integral-Derivative controller) of the corresponding components and other parameters of the control system.

The influence of the frequency inverter operation on the application limits was ignored.

Change minimum high pressure or minimum frequency.

Influence of part load operation on the suction gas temperature in booster systems.

Evaluate options for incremental change of parameters, use liquid injection, install desuperheater.

Liquid slugging

Compressor is flooded with liquid refrigerant.

Use fail-safe electronic expansion valves, check piping installation, check size of accumulator and refrigerant charge.

Compressor flooded with oil.

Faulty oil management (Ölmanagement), too much oil in the system, check piping installation.

Defrost mode.

Reduce the number of evaporators in defrost mode in parallel.

Moisture in the system

Inadequate evacuation.

Check vacuum pump and vacuum gauge connection. Open and check each area of the system.

Leakage test carried out under vacuum.

Carry out leakage test under pressure.

Contaminants

Incorrect cutting of pipes to length.

Use a pipe cutter.

Faulty soldering.

Use inert gas.