freezer gas in a siemens domestic freezer?

When installing freezer gas into a domestic freezer after a component is fitted ie compressor, is there a need to pull a vacuum into the system to get rid of all impurities and moisture before the new gas is installed. As when you fit a new component onto a car A/C system.
The reason I ask is I have just had a new compressor fitted to my freezer and since then it takes forever to cool down after putting fresh food into it, it has an alarm on it to tell me when the temperature is too high and it takes about 12/24 hours to reach the correct temperature. it never did this before the compressor was installed. cheers in advance.
I have already asked this question but must have entered it on the wrong ask section.