Heating power XC70 /MJ 2009

Hello, the heating power of my xc70 is no longer satisfactory. Even after 30km of highway only lukewarm air comes out of the nozzles. Even at requested 30 degrees, the air conditioning system probably means it is warm enough and only waves a little warm air to the interior. The fan makes trouble and also turns automatically high, although it is never controlled to maximum. Can I do manually, on the fan itself is apparently not. That could be more if it should. In the lukewarm car set at the automatic 15 degrees the fan drives to maximum speed and the air conditioning cools. The temperature sensor detects at least the temperature range and regulates void. The cockpit unfortunately has no water temperature indicator anymore, I have no idea if the cooling water is not warm enough to deliver what to the heating (thermostat always open?) or whether the small circuit already cooks (thermostat always too). islauf is actually sitting the heat exchanger? A message or warning light in the cockpit did not come yet. Did someone already have the problem and could solve it? Tightened to answer and recommendations… Tom