1997 240sx se, AC knob issue, kinda weird.

[fleali88]

My 97 240, the AC works, but only on the number 4 setting on the knob, on 1, 2, and 3 nothing even blows out, but on number 4 it turns on and is cold. any one know what could be wrong? thanks

[ward28465]

possibly a high resistance issue

[jaylivesinsf]

I have the same exact problem on my '95 240sx. I bought another control unit, switched it and it did the same exact thing. The fan/ac blows on setting 4. 1,2, and 3 do not work at all.

What do you mean when you say it's a high resistance issue?

[fleali88]

lol at least im not alone, what i do notice is that the ac clutch will engage on settings 1,2,3 just no air gets blown out at all, but as soon as you go to 4 it works very well, gets too cold though lol.

i am also curious as to what a high resistance issue means.

thanks

[nismo611]

you need a new diode mine did the same thing.

[the converted]

There's a set of resistors for the blower motor, yours are burnt out.

http://www.courtesyparts.com/2....html

[ward28465]

fan speed is regulated by varied voltage. Ex. when fan speed is switched to 1 it gets 1V which makes it move. the faster the fan moves the more voltage it needs. the voltage travels through different resistors to match the voltage to which fan speed you selected. high resistance means there is something wrong on fan speeds 1-3 that is blocking the flow of voltage to your blower motor. hope that explains well enough.

[fleali88]

does anyone know what parts should be replaced/checked specifically to fix this problem? i just hate either being super hot or super cold lol. thanks alot for your input.

[the converted]

http://www.courtesyparts.com/2....html

[fleali88]

well thanks, i just bought it, ill see if this works, but i have the service manual and i read about it, i think this will work. now i need to read how to get to this thing lol

[fleali88]

i see that its very accessible , under the glove cmpnt. i also see the solder that has failed, i am going to re solder it and see if that works, i touched the contacts with a fuse and all the settings started working lol, thanks alot guys for your help

[fleali88]

so i re-soldered it, and it works perfectly, thanks guys