Nissan Repair: Heater and air conditioner dont work, work question, blow air

Question
QUESTION: The heater doesnt blow hot air nor does the air conditioner blow cold air on my 2000 sentra se.Could it be the temperature control switch. that regulates the temp. inside the cabin.

ANSWER: R,

If there is no air the blower motor is probably in need of replacement.  If there is air but it is not hot or cold then you need to look at the blend doors not working properly.  Most of the time the temperature control switch is defective.  If you look under the passenger side of the dash you can see the actuation when you turn the control from hot to cold.  If there is no actuation you could have a defective control.  This is a process of elimination job to see what is going on.  Email me back and let me know if it blows any air.

---------- FOLLOW-UP ----------

QUESTION: Thank you for the advise, yes it does blow air, my wife said it matches the temp outside the car.You had mentioned the blend doors possibly not working. Would the blend doors be located between the firewall and dash?

Answer
R,

The door between the firewall (cowl) and the dash is the one for outside air as opposed to recirculate.  There is another one in the car that blends the air from the heater core to the airconditioner.  That is the one that I think is messing up since you only get air that is neither hot or cold.  And, there is another door that controls the air from the defrost to dash to floor...