pressure control unit 25 may communicate information directly to the compressor controller 8 such information may e g comprise information relating to how many refrigeration entities have been switched on active and or off inactive during a specific time interval fig4 shows two graphs illustrating a prior art control method the upper graph 18 shows variations in evaporating temperature as a function of time in a refrigeration system which is controlled in accordance with a prior art control method as can be seen the temperature varies relatively much but is maintained substantially within a specific range of temperatures the lower graph 19 shows the compressor capacity as a function of time of the same refrigeration system and during the same time interval each change in compressor capacity corresponds to a compressor being switched on or off as can be seen from the graph 19 compressors are switched on or off relatively often in order to maintain the evaporating temperature within the specific temperature range this causes a lot of wear on the compressors fig5 corresponds to fig4 but in this case the two graphs illustrate a control method in accordance with the present invention the temperature variations shown in the upper graph 20 are smaller than the temperature variations shown in the upper graph 18 of fig4 thus the evaporating temperature is maintained more stable when using a control method according to the present invention more importantly the lower graph 21 shows that the variations in compressor capacity are much smaller than the variations in compressor capacity shown in the lower graph 19 of.