AviPrink

ok i will try

You need to cunnect pin 4 before shunt Not after as little mistake in my diagram

Yes i agree with you, but it works for me. I also have designed low side current sensing. It also works fine for me

current capacity is depends on relay. use powerful relay for high current capacity.

yes you can use

As i mention in my post this is not energy efficient as compressor based refridgeration system. It cunsume about 60watt of power @ 12 volt. Produces lots of heat.