Nissan Repair: a/c and heater, firewall one, history of the car

Question
i have a nissan 1995 240sx. neither my a/c or heater works on the car. yes, the blower works. i have no idea of what the repair history of the car might be because i just recently bought this car. i figure that the a/c just needs freon but im not to sure of how to figure out what might be wrong with the heater...any ideas?

Answer
Richard,

If the heater and the airconditioner both are not working but the blower works then I would be asking if air comes out of the vents?  If air comes out of the vents but it is room temperature and does not get hot or cold I would be looking at the blend doors and the motors or cables that actuate them.  You did not say if yours is computer controlled air or not.  If it is I would check the fuses first and then get under the dash to look at the actuators and see if they move.  Also, does the compressor come on when the air is on?  If it does check the line going into the firewall to see if it gets cold.  If yes you have confirmed that there is a blend door not working.  No heat you need to check the hoses going to the firewall.  One should be hotter than the other.  You should have a cutoff valve that prevents hot water entering the heater core when you have the heat off.  I would check the valve for proper operation.  It is close to the firewall and you just need to follow the heater hoses to the firwall to find it.  Check it out and email me back if you need more.