Should have added that the clicking is every 3 or 4 seconds.

Steve

What settings is the climate control panel on?

In weather like we've been experiencing recently, climate really
struggles - with the compressor drawing significant power from the
engine.

Doesn't sound too untoward if you have it set to 'auto' and have set a
temperature above 'freeze my nuts off'.

I had similar on 164.

First of all the lack of power should not be noticable on a GTA... I didn't
feel anything on 164 TB.

The problem may be on the airco cooling. My system was charged with gas to
factory figures, but when it was hot the pressure in the sustem was higher
than it should be. The source of a problem was to small overflow threw airco
radiator - flies, dirt, etc. I spent few hours cleaning that. The sound you
describe may be from airco compressor - check that (should be on lower
passenger front section of the engine). If that is the part making the
noise, it switch on/off too often, maybe because of too high gas
compression. Easy to check compression on any airco service point.

Regards
Szymon

Sounds like the outfit that changed the hose and gassed your
airconditioner put too much gas in the system.  So the compressor is
cutting in and out very frequently.
Get them to dump some of the gas.
Would be better if they can load exact weight of gas required - back to
factory spec. Otherwise it's essentially guesswork.