If it leaks it leaks. Central units are self contained with no external rotating shaft seals to leak. If the tech came out and added freon without detectng the leak, either he did exactly what you directed, or he is a BS artist hoping for a repeat job.
Freon could be leaking anywhere in the ac system. A colored dye can be added to the system, then seen with a special light to find the leak.
What will happen if u I added power steering fluid to a leaking power steering pump
it will get fire slowly
slow
It melts slowly.
Why should HAc be added slowly to the milk with through stirring?
broken hose to the power steering reservoir or the rack on the firewall is leaking badly or the reservoir has a hole in it.
It melts slowly.
This can cause your seals to start leaking
Write was is in your mind?
To avoid a violent reaction.
==Suggestion== I have read that the newer caravans have a problem with the rear air conditioning hoses eroding and leaking, you might check this out, if this is the problem the dealer will fix it for free. I have had this problem in a different type of vehicle, found the water was slowly leaking into a cylinder and going out the exhaust pipe,the leak was slow enough that it really didn't effect performance. Finally started leaking enough that steam constantly came out the tailpipe.