How to repair bulb failures in the heater panel

[Parrot of Doom]

A couple of bulbs had gone, in the heater panel, and the cigarette lighter. Heres how to replace them:

Tools required: 1 small philips screwdriver, 2 thin flat bladed screwdrivers, car radio keys, soldering iron, copper braid, replacement bulbs. If you're no good at soldering, either find a mate who is, or take the heater panel to the nearest TV repair shop. You can drive the car with the panel removed, however hot air will drift through the vents.

1) Remove the panel surrounding the gear lever by pulling upwards from near the oddments/drink holder bin. This is much easier if you put the lever in N, you'll need the keys in the ignition to do this though. Don't worry, the car shouldn't start unless the lever is in P.

Once removed, you can disconnect the cables if you like but they're long enough that you can pull it over the gear lever and put it to one side.

2) Pull the ashtray out (small lever on the right). Look at the bottom of the compartment, behind the gear lever panel you just removed are two small screws. Unscrew them and put them somewhere safe. You can now remove the ashtray/lighter compartment completely. Pull it from the bottom, and gently bring it out. Careful you don't scratch the veneer on anything. Theres a cable on the rear that goes to the cigarette lighter, pull the connector out. The bulb is part of the connector and is in a black housing. Remove the housing from the connector, and then pull the bulb out of the housing. Be aware the bulb needs to go back in with the same orientation.

You should probably ignore whats in my passenger footwell

3) Now the ashtray compartment is out, put your hand underneath the sunglasses compartment, right to the back, and reach over the top edge. You'll find a clip, pull down on that clip with your finger, and that will release that compartment. It slides out on rails.

4) Remove your radio. I've left this bit out as mine has different keys. Whatever radio you have, remove it with the keys, unplug everything from the back (take note of what goes where), watch the plugs or the radio don't scratch the veneer.

 

[Parrot of Doom]

5) Once the radio is out, you will see 2 screws holding the fascia in. They're just above where the radio would sit. Unscrew them, and put them somewhere safe. Note, the screws that hold the fascia on are shorter than the ones that hold the ashtray in - don't get them mixed up.

The fascia simply pulls away, in a manner not dissimilar to the gear surround:

The fascia will have a couple of wires going to the back - again, you don't need to disconnect them, theres enough room that the fascia can slide down between the driver's seat and the gear lever. Here are the wires:

Once the fascia is off, you can see the heater panel completely exposed:

Now I was quite surprised here. The controls aren't held in by anything other than 2 clips at the front. Possibly someone has been at it before and forgotten to replace something, there are 2 holes, 1 in each corner, that look perfect for screws. I couldn't see any receptacles though.

Please make sure you note the position of the air direction control at this point

6) Remove the heater panel - this is quite easy, just put your thumb on each clip (top left and right), and pull the panel out. Theres a large connector on the back with a gray retaining clip. Rotate the clip, and remove the connector. Its a very neat design this bit, I was impressed

 

[Parrot of Doom]

When the panel is removed, you'll notice two big yellow 'sticks' poking out the back of it. These are the air direction controls, so don't mess around with them or you'll end up sending air to your feet when you really want it to the windscreen!

Take the panel out of the car, and head inside for a brew. The panel splits quite easily, there are numerous plastic clips around the circumference, just get the flat bladed screwdrivers in there and prise it apart:

At the back of the panel is the air direction control - you can see a small hole for alignment at the bottom:

You'll also see a small 'arrow' on the stalk, use that to double check that the control is aligned correctly.

Now I thought a couple of bulbs needed doing. One for the air direction control, and another for the recirculate button. But it turns out that inside the panel the light is refracted around inside plastic light guides, and only 1 bulb had actually blown. Unfortunately, the only way to get to that bulb that I could see is to remove the PCB. In another bit of poor design, the only way to remove the PCB is to unsolder the heating controls from either end of the board.

Anyway, only one bulb had gone, so I just desoldered the right hand heating control, bent the PCB a little (see above), and grabbed the bulb from its socket (at least its socketed, other manufacturers would solder it directly onto the PCB!) You'll definitely need desoldering braid, or you'll ruin both the PCB and the heater control pins.

The bulbs at the back of this are tiny little 12V 1.2W jobbies, I bought a couple from the nearest Merc parts desk. They're less than a quid each which I thought was acceptable. I bet you could get them from RS for 10p but you'd have to find them first.

So, put the new bulb in, push the PCB back together, solder the heating control pins back in, snap it all back together, and reassemble in the exact opposite way to that described above. The most difficult bit will be getting the two yellow stalks on the back of the heater panel, into their receptacles. Persevere, they came out, they'll go back in!

Job done.

 

[Parrot of Doom]

To discuss the contents of this post, please do so in this thread:

http://forums.mercedesclub.org.uk/showthread.php?t=26199