I've noticed recently that the dials on my heating system seem to have absolutely no fine control. On the lowest setting (turn all the way to the left, think it's 17 degrees) the air is cool as you would expect

However turn it up one notch and it is immediately red hot, you can then turn it all the way up to the highest setting and it's the same.

It's literally cold, or hot and I'm sure it didn't use to do this before. I'm getting no fault codes showing up and it's quite annoying not being able to get a comfortable temperature

Any ideas?

Thanks

Where is your hot/cold vent control set at (the red and blue horizontal wheel) 2012 TDV8 Vogue (L322)

Just sat in the middle

I have this issue too. I haven't looked into in yet but it's hot unless on full cold.
The face vent dial works as expected.