# Heater And Clock



## BigAl (Feb 24, 2004)

My '93 maxima has a peculiar problem. The clock and SOME heater control lights are intermittent. When one is off, so is the other. Whether the lights are on or not, the clock sometimes does not light up. I have studied the factory wiring diagram and have not been able to trace a common path for these two lighting areas. No obvious wiring damage or looseness either.

Any suggestions about where to look?


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## Matt93SE (Sep 17, 2003)

it's the high voltage power supply for the fluorescent display in both units- it's not something in the car itself.

yank the units apart and resolder the connections on the large resistors in each of the power supply units.

I've fixed probably a dozen clocks (for $35, shipped- email me if you're not up to the work) but have yet to touch the heater controls. I've heard it's the same deal though. just poor solder connections in it that go bad over time.


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## BigAl (Feb 24, 2004)

*At the same time*

I'll pull the clock and check it. It seems strange that both the clock and the heater backlighting would go on and off together if there were different power supplies for each. I still suspect that there is some common point in the wiring at fault.


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## Matt93SE (Sep 17, 2003)

that is weird, but I don't see how those two are dependent.. there's no common wiring on them..
the clock gets battery, ground, ignition, illumination, and dimmer circuits (I think they get dimmer ckt. possibly two grounds)

the heater controls obviously have power and ground, but I don't think they have battery power... is yours the auto climate control or manual? the auto control uses an EFL display just like the clock- which are both prone to failure after several years (at least the Nissan ones)
the manual climate control just uses regular incandescent bulbs.


the only thing that could cause both of those to screw up together is if your illuminuation wire was damaged somewhere (bad stereo install???) but it would happen on ALL the lights in the climate control unit, and not just some of them.

what about your other dash lights?


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## rcy (Mar 5, 2004)

BigAl said:


> I'll pull the clock and check it. It seems strange that both the clock and the heater backlighting would go on and off together if there were different power supplies for each. I still suspect that there is some common point in the wiring at fault.


Can't help you with the clock (mine works fine), but Matt knows his stuff. However, if it's the backlighting on the climate control (I'm assuming you have the Automatic Climate Control), and not the display screen itself, the solution is simple. Remove the climate control and replace the lights that backlight the buttons. Don't get them from Nissan, go to Radio Shack and get them. They're little tiny bulbs with long thin leads on them. On the back of your ACC behind each button, you'll see little cap things that you turn 1/2 turn or so and they pop out. The bulb leads thread through this cap things. In my case (the car is 12yrs old) most of the bulb leads were just loose. Hope this makes sense (if you take the ACC out, you'll see what I mean).


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## BigAl (Feb 24, 2004)

Thanks, guys. It's the manual heat controls and yes, it's the backlighting. The other day it was warm and the clock came on and the backlighting did not so I guess they are not physically related. It could be a cold temperature thing that they went out at the same time, or maybe just a coincidence. When I get a warm weekend, I'll pull the clock out and look at it, and also look for lamps to replace on the heater control. I have an aftermarket CD player in the car with a clock anyway. If I can't fix the original unit, I'll make a nice looking blanking plate to replace it. I just don't like to look at broken stuff.

Peace to you all,

Big Al


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