I have a 1.6 Nissan serena and when I start the engine there is a very loud noise like a fan blowing from under the middle seats. Cold air also blows out. It is very noisy and I have no idea what it is. I am getting heat from the heaters in the front and my temp gauge is fine and I have plenty of water so its not the engine. Can anyone tell me what it might be and how to fix it please?
On the Serena you have a huge fan under the engine. Usually this fan starts only when you park after having climbed a steep mountain road in summer. Apparently it prevents hot air accumulating around the engine/pipes. Probably something is wrong with the sensor or the contact commanding this fan