It may be a faulty recirculation button. Does it work ok if you not got auto pressed on. ? I never use recirculation myself as it just blows stale air around the car after a few mins. So 2 things you can do is eaither buy a 2nd hand heater control unit (as may be faulty switch) or don't bother usein...

Yep fitted myself easy to do they have foam double sided tape on them.

Only got the original nissan 1's fitted on mine they fit good as shaped to the bodywork will post link later
Ouch gone up £50 from when i fiited mine 2yrs ago
https://www.ebay.co.uk/itm/251534070704

https://www.ebay.co.uk/itm/145658997252
cheap part to replace so i would start with that first and see if it fixes the problem, does sound like a faulty switch though,
update once you have replaced it.

Did you get the air out of the fuel lines when replaceing the fuel filter ? . Correct gloplugs fitted 4.4v think they are on the j10. Battery checked just incase it needs replaceing ?

Should return after been pulled. Maybe yours is catching on trim etc

Check fuses 1. 7. 17 behind glove box before spending lots on parts.

these can all be turned off if you don`t want too look at them on the dash.

https://www.ebay.co.uk/itm/262359231517

Or try a scrapyard aswell

Normally sensor fault. Give the car a good clean at the front and that normally sorts the error out if the sensors are covered in dirtcetc. If its still there after that trip to nissan to get them to check it out as new car so should be covered