Split-unit issues

[antio]

Hello,

We have a split unit installed. The outdoors unit sits 2 floors above and the indoors units are 2.5 and 3.5 KW respectively. This is a new installation and we have 2 issues:

1. When I power on the big unit I can hear the refrigerant running through the pipes of the small unit. It's a distracting sound, especially if the small unit is off, as it's in a small quiet room. However, when I am running the small unit, the bigger one is quiet.

Is this normal and is there any way of stopping it, if we don't want to have both units on? (e.g. a valve to stop it from running to the smaller unit if it's off?)
(if it matters, the order is this: external unit -> big internal -> small internal)

2. The big unit will heat, but will not cool. Again I can hear the refrigerant running through the small unit and if I power the small unit up it blows out very cold air. However, the big unit is blowing out room-temperature air (maybe a tiny bit cooler). I find that odd, as heating works fine on both units.

Any ideas would help, before I call the engineers to have a look. Basically, I'd like to know if they've messed up during installation, so I can be prepared. I'd really like to address the noise issue, as it's quite distracting.

Many thanks in advance.