Hi I have 98 Nissan Maxima. I recently changed the thermostat in it and ever since then my fans will stay on, and I am not running the a/c either. Can you please tell me what could be causing them to turn on and stay on? This did not happen until after the thermostat was changed. Thank you.
Were there any other repairs/maintenance done prior just before the problem started? If not, it sounds like the wrong thermostat has been installed, or the new one is faulty.
What caused you to change the thermostat?
You should check if the coolant liquid is between minimum and maximum. If you need to add more liquid, don't mix different liquids colours (I don't remember why). And please be sure it's not hot, else you will get very bad burns and injuries.
Sounds like you had an air bubble trapped in the cooling system after changing the thermostat. Check the coolant level. (Id also make sure the coolant temp sensor connector is hooked up, maybe it was left unplugged)
If coolant temp has not been plugged back in, the deafult for the ecu is to run the fans all the time as a precaution-this sounds like the issue as has been sadi above.