97 DX Coupe No Climate Control Lights

The two bulbs were just replaced but do not work, everything else works. I have Dash, Hazard/Defrost lights, all the LED's work fine in the selector switches. Dimmer switch has been bypassed after I noticed it smelled like burning plastic inside the car. How do I go about fixing this issue? I have a multi-meter, tools and time to tackle this now that the weather is cooler. Ever since I got the car back in May it has not worked and driving at night and with more dark damp days to come for winter I want to fix this. Thanks for your help.

 

No one? Might be coincidence but one of the 3 lights near the bezel are out in the cluster, not sure if that has something to do with it? Also I don't know how long those 2 74 bulbs were out, all the lights and things inside and outside the car are 20 years old. Car was built in late 1996, so yeah just rambling now.

 

Make sure the bulbs are in the correct direction, they won't work if they were inserted backwards. Also I believe they are wired in line so if the first one doesn't work, the second one doesn't get power.

I believe there is also a hvac light fuse under the steering wheel

 

The Fuse Box Diagram on the Fuse Door Says there is a 7.5A Heater / AC Relay which is fuse #17 but I don't know if that would be the one you're talking about or not? I will go pull it and check to see if it changes anything or not.

Anyone else have something to add as far as checking things?

 

Checked #17 with a new fuse and still nothing, I did not check to see if fuse was getting power or not. Blower works just fine from Off to 4 even though it sounds like a hamster wheel gone mad! One day at a time I guess

 

If you're smelling burning then I would double check that bypassed dimmer switch. Could have a loose connection?

 

Burning smell went away after the dimmer was bypassed.

When I had the module out I tried jumping the leads on the PCB to the wires that feed power to the bulb and it would not light up, but if I put it straight to the light bulb it would light up. Could be the PCB is bad after years of hating up from power source with no bulb in there?

 

That would be un usual, you can check the points on the board with your volt meter to verify they have 12volts on the connections to the bulb socket.

 

You could have cracked solder on the PCB, like what happens to main relays. Resolder the board and get it so when you apply power to the pins of the harness plug, the bulbs light up. Then re-install in the car. If you are using conventional incandescent bulbs (not LEDs) like the original ones that came with the car they will work plugged either way.

 

Thanks for the feedback guys, for now it is all back together. I plan on changing out the head unit soon and when I have it all apart for that I will definitely take a look at it again.

 

There is a connection problem of the illumination power lead, [red/black] or illumination ground lead, [red] from DLBC, [dash lights brightness controller] most likely at the HVAC wire harness plug, or possibly a cold solder joint on the HVAC head circuit board.
All dash illumination lights get their power from the same source, combination light switch through fuse in under dash fuse box, [if any illumination lights work, switch and fuse are good, any illumination light that can be dimmed gets it's ground from the DLBC the ones that do not dim are chassis grounded.

The illumination lights for the HVAC head are the same as the clusters and dim and if the others work it can only be a connection problem to the HVAC head. 94

 

Also before starting work on the head unit do yourself a favor and pull a "new" dimmer switch from the local junkyard & un-bypass it. Might help with the issue.