Hello,
I have a Mercedes 190 2.5 diesel and it needs a top up.
Now it's getting hot here in MALTA 35°C and more.
Can some one tell me exactly how to check and add refrigerant in my Mercedes.The gas is R12 and I have a cylinder because I bought a cylinder few years ago.

How much the low side will read and how much the high side will read?
How much I will rev the engine 2000 rpm?

Thanks