1992 240sx heating/cooling system help.

[bxiong]

i have a 92 240sx my heat and my a/c just went out.... i try turning it on but no air blows and i dont know what the problem is.. any ideas what could be the problem? i"m thinking that it could be the heater core but i dont want to waste a ton of money if that's not the situation..let me know if you guys know a solution. thanks

[KoukiDrftr]

its the switch or the blower motor

[§treet_§peed]

the heater coil?

[ZEDEX32]

Is your engine temperature normal?

[Z U L8R]

if no air blows when you select the fan to come on then your blower motor's not coming on, which would lead you to test the blower motor fuse(s), if the fuse(s) are good then try powering up the motor and see if the motor's any good. if that tests good then you move on to the switch, if your fan will come on but only on one particular setting then the problem is the blower resistor, basically any diagnostic you do, start with the most common/easy things to check, then you move on to the next, until you find something that is not doing what it is supposed to, then you see WHY, either it's not getting the voltage/ground it needs (if it's an electrical part) or the part/switch/sensor itself is bad. when you understand how a system works like understand what things in the cooling system work together in your car that give you the end result of hot air blowing out of the vent, then you'll be able to diagnose your issues.

your heater core is a little "radiator" basically that's behind the glove box. as your coolant flows through the motor it passes this hot coolant through the heater core which is inside the car, the blower motor is an electric motor with a fan (looks like a hamster wheel) that pushes air through the vents/slits of the heater core therefore on the other side the air that is moving is now warm/hot. that air is then maneuvered throughout the car via some duct work and then out to the vents where it finally blows this hot air onto your skin and you're like "heat feels good."

the ac system is similar but an entirely unrelated system. to keep it simple you have an evaporator core behind the glove box which basically acts as the heater core but instead of being hot, it's cold. so the blower motor blows air across the cold evaporator core then to the vents then to your skin and you say "ac feels good."

now you have what is called a blend door, which is a flap/door that blocks the air blowing from the blower motor. when you select that you want heat, it pulls a cable that moves the blend door to block off the evaporator, so the air will blow off the heater core and be hot coming out of the vents, when you want a/c, the blend door blocks the heater core so the air from the blower motor blows across the evaporator thus producing cold air out of the vents. and if you want warm then it blends them both hence the name BLEND door =]

if your coolant never gets hot enough to have HOT coolant in the heater core, then the air blowing off the heater core won't be hot thus you will not have heat. where does your coolant get hot? In the motor cause the motor gets hot, and your motor needs a way to trap the coolant in it until it can warm up to the correct operating temperature, what traps it is the thermostat. once it reaches operating temperature the thermostat opens and the coolant is no longer trapped, now it flows.

anyways i'm bored at work, i hope that was enough info to help you solve your problem, if not, msg me