Vent Door Control - Dead

[p00t]

Ever since I bought my 93 240sx the vent control (upper vents, lower vents, defrost vents) occasionally would not work, in otherwords it would be stuck on the position it was last set to before it decided to be a homosexual. It is very intermittent and random, but seems to happen more often in cold weather. This problem has previously been ignored because (A) When the windsheild started to fog up the vent door just so happen to be stuck on windsheild defrost. (B) When it was becoming more frequent it has been warm and no need for defrost. Unfortunately tonight it wasnt working and it was stuck on the upper vent mode, it was raining, windsheild fogged up 1/2way through the trip. It was not safe at all, and I dont want it to happen again.

Symptoms when this occurs are as follows:* Normal illumination of the unit is present with headlights on, but the LEDs on the buttons are not lit up (which show which vent mode is selected).* No matter what button I press the vents the air comes out of does not change.* Temperature control lever works perfectly.* Fan speed control lever works perfectly.

Any comments are appreciated. I will be pulling the control unit and checking the fuses tomorrow. If the vent door motor dies, does the whole circuit get cut or will the buttons still light like normal but doors just wont actuate properly? Any amplifiers or resisters that could go bad?

Thanks in advance!!!!!!!!!

[NISTECH]

this is not a common problem on any nissan i have worked on but being the combination of the lights not coming on in the control haed and the actuator not moving.I suspect your problem lies in your control head,on the circuit board specifically. Sounds like the main power supply has a cold solider joint. This kinda failure in electromics is common to temp differences. pull the controller out and look for a fish eye around one of the joints on the circuit board. you may need to pup the covers off the control head to see the board. also check the connector that plugs into the control head for corrosion and a possible terminal pin backing out.

[p00t]

nistech,

i took out the unit and low and behold it would "blink" on when i wiggled/pushed the harness with a lot of force. Im sure the connector is plugged in good so it must be a wire or terminal pin not making contact.

ill check inside the sucker for broken solder joints also, thanks.

[NISTECH]

by that i would say its a soilder joint where the connector is solidered to the board.