My car (a 2013 Octavia) heater seems to have gradually got worse over the roughly three years I've had it, to the point where it takes ages to get any heat and I have to start my morning commute with fogged windows. I've checked the engine coolant levels and they seem fine, and the engine temperature has never been a problem, so I don't think it's that.
What else could it be? Would a coolant flush/replacement be likely to sort it?
What else could it be? Would a coolant flush/replacement be likely to sort it?