2011 Nissan Rogue Coolant change

[lk777]

In one of the local repair shops I was told that they are going to do a full cooling system flush by disconnecting a lower radiator hose and applying some air pressure.

And,of course, without any further explanations. One guy told me that they are using a coolant exchange machine the other one told me that they will be using above mentioned method.

I know that there are some coolant exchange machines that do a full coolant flush and refill, but these machines are connected by disconnecting an upper hose. These machines use "engine-off process".
Some other, cheaper, vacuum-exchange machines get the fluid out of the radiator itself and then refills it.

So now I have a question: Can I trust those guys that they will do a full flush on the cold engine by disconnecting the lower hose only?

I can't see how it can be done when looking at the Engine Cooling Diagram.