The heaters only blow hot air when driving, and gets hotter the faster I drive..
The coolant level is fine as that has been topped up recently.

Where do I start with troubleshooting?

 

Sounds like its possible you may have to flush your system to clean out the heater core.

 

Maybe you need to dump this car (junkyard, possibly) and buy one that requires less work. You are in Finland, ne? How hot is it outside: are you trying to cool the car with the air conditioner or are you trying to control temperature of the incoming heat? I respect that English is not prime, but you need to be more specific with your issues . . . . which are many . . .

{Maybe this is my fault since I recommended this forum to folks on the Facebook XJ X308 group grope: now lots of questions from 3.2 owners . . . buying ultra cheap Jags throughout Europe that probably should have been retired . . . reminds me of my youth when everybody wanted to know how to hot rod a 'deuce coupe flathead V8 . . .}

Seriously, keep the questions coming: the best guys to answer your questions are here!

 

If I recall correctly, the duty on imports in the Scandinavian countries is insanely high, so maintaining and improving a car is necessary.
That said, I agree that we need to understand the problem. If you are trying to cool the car by decreasing the temperature setting but not turning the A/C on, I think the blend door is frozen, possibly from lack of use. If that's the case, I don't see a way of correcting that without removing the dash and center console. Probably the A/C system will not cool the car either.
I hope I'm wrong, and maybe someone more knowledgeable will provide a simpler solution.

 

Have you checked the climate control system for error codes, and gone through the test cycles? See post number 8 here: https://www.jaguarforums.com/forum/x...54/#post454861

 

Hi Jhartz, the issue is when I control the temperature of the incoming heat, it is not hot; even at its max setting.; Hei Jhartz, asia on, kun ohjaan tulevan lämmön lämpötilaa, se ei ole kuuma; jopa sen maksimiasetuksessa.

Hi, the temperature does not get hot at all. Thank you for the advice.

There are no error codes, oddly. I did have a previous issue with the coolant and I spoke to a Jag specialist and he did say he'll have to remove a few things under the hood and figure out the issue.

 

Lots of threads on this forum on researching heater problems: most likely, as noted above, your heater is likely clogged up; your thermostat may be stuck; the blend motor may be bad.

 

I've noticed tha atleast my car is very concervative to cool cabin with just cool outside temperature when ac is not turned on. It will start to use outside air to cool but it takes time. If in that time ac is turned on it starts to cool instantly.

I'd guess that there might be heater valve stuck open. I dont think that these cars has contiously flowing water to the heater core. In first post owner says that the heat is getting warmer at higher engine speed. To me this means heater water pump is off as it should and valve is not. This when driver asks low or at least lower than outside temperature.