They don't charge it at the dealer before delivery, the refrigerant is filled at the factory; with that being said, it is a possibility that it wasn't filled, however, a more likely scenario would be that a leak is present somewhere in the system.
I had the same problem earlier in the year. Switching the car off for a few minutes solved the problem. Subsequent to this, we have been having very hot weather, greater than 40° for over a week and the air conditioning has worked perfectly. I suspect the issue is not so much gas levels, but a random software bug turning the heater on to full heat. I have flagged it with the dealer and the feedback from Ineos Australia is they have seen something similar and it may be software related.
Hi Gui, today with about 550km/340mi on the ODO the same in my Gren. After a short lunch break and continuing the tour everything seems fine, cool air in the back. Very odd. I'll definitely report this to my agent. I'm keeping my fingers crossed that this was a one-off experience...
My air con was poor when I collected my vehicle……..this is exactly what I was told and was the fix. Air con works now, in its own Grenadier sort of way….
Exact same problem here for the last 6 months. Before the last software update in December’23, the airco worked fine (if not leaking gas
). After the update; heating doesn’t make sense, it’s all over the place like heating in the back and not in the front, and now with better weather out, cooling behaves very similar, no cold out of front vents but cold in the back. 
Hi @camshaft6au Yes, this is a software issue. Turning off the ignition, waiting a little and restarting usually helps. Ineos is aware of the issue and is supposedly working on it.
Hi dreamalaska, In my opinion it would be best if all vents on the HVAC system were controlled by cables and levers controlled by the user. That is about as fool proof as you can get. On the other spectrum, the New Defender HVAC system has worked flawlessly for me for 3 1/2 years and I like how you can easily control the temperature to the exact degree you and your passenger like. I would take either over the current Grenadier set up, although I am hopeful that software updates may improve it some. DaBull
Don't be surprised if it pops up again. Mine does the same thing, blows cold in front and super hot in the rear. I'll turn it off for a bit then it goes back to normal or whatever normal is for HVAC in the Grenadier. Anyway after a while if I turn up the temp to warm the air a little the front vents will be warm but the back vents will be extremely hot and turning down the temp will not do anything for front or back. The only way I can reset it is to park the truck for a few minutes. The Grenadiers have the least intuitive and worst HVAC systems of any car I have ever owned. I do love the truck though.
This is exactly the right approach. I also posted this at some point last summer. I always control my heating and air conditioning in combination with the Auto button. Then the temperature can be adjusted from very cold to hot. It is important that Auto, the air conditioning button and the rotary control are always seen as a single function. That's why I generally have no problems with the system.
