Volvo Repair: 1998 s70 very little heat, upper radiator hose, heater cores

Question
Hello,

       My 1998 s70 has very little heat. The fan is blowing fine though. So I would guess thermostat needs replaced. Well the check engine light is on which I am told could be tied into the thermostat.

What is weird - As soon as I start the car the cooling fan at the radiator starts running as if the engine was hot and needs cooled - like in the summer.

I am puzzled! any ideas?

Thanks so much

Answer
Hello,
      The first thing you must do is...make sure that you have enough anti-freeze...check while engine is cold.
    Check to be sure that there no air bubbles/gaps in cooling system...often engines need to be "BLED"in their cooling systems...this may be your case..
          Thermostats do fail...cheap repair.
         
      While engine has run for 10 minutes or longer....feel upper radiator hose...it should hot.
       If possible...feel lower radiator hose...it should be hotter than upper hose.

      Heater cores rarely get clogged...in newer cars.

               Good luck,
                           Bilbo