[Bali]

…I have to drain all the coolant out first is this correct?

No. So long as the rest of the cooling system is still closed you do not lose much coolant.

 

[Bali]

I have drove my car for 3 hours this morning normal and traffic driving no overheating and gauge perfect at 12 o'clock. My A/C is empty but when I press the AC button the electric fan now spins for around 30 seconds then goes off, before I changed the temp switch it didn't run at all even with the AC on. My question is the reason it's turning back off with the AC on because it's not cold enough hence not needing to stay on? I have my m.o.t on Friday so I am going to ask the garage to re gas my ac and see if it stays on.

What do the Engine and Climate Control fault codes show you?