Heater Control Illumination
03-22-2007, 07:33 PM
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Heater Control Illumination
For ages, I'd been bugged that only one of the three heater control knobs of my 190E was illuminated when the headlamps were on - I also suspected that there were other non-functioning bulbs, meant to light up the sliding ventilation fan speed control, and more.
Sure enough, a question asked on this forum confirmed this, so armed with some ridiculously expensive 12v 1.2w bulbs purchased from Hellfords, I set about 'getting-in-there'
The bulbs WOULD have been cheaper from my MB dealer - part number 072 601 012 230, around £ 0.70 each
To clarify before we start, there are 5 bulbs in total - one behind the centre of each of the three knobs, and two further bulbs - one behind the middle knob, and one behind the left-hand knob.
These last two illuminate the knob surrounds, and the five-stage sliding fan speed control
Note - my car does NOT have A/C ...
Step 1 - Remove Knobs
See Photo 1 = http://i156.photobucket.com/albums/t...heaterpic1.jpg
They simply pull off - I'm using a pair of 'vice-grips', with a piece of rag to prevent damage to the knob.
Mine needed a fair old tug to get them off !
Step 2 - Knob illumination Bulbs
See Photo 2 = http://i156.photobucket.com/albums/t...heaterpic2.jpg
If it's just the bulbs behind the knobs that you need to replace, removing the appropriate knob is all you need to do - you'll see the bulb in the end of the tube that the knob rotated around. Pull the old bulb out, and press the new one in, making sure that the contacts on the new bulb line up with the socket - a bit fiddly.
To get to the other two bulbs - read on ...
Step 3 - Remove Hex Nuts
See Photo 3 = http://i156.photobucket.com/albums/t...heaterpic3.jpg
Not sure what size these nuts are, but my 27 mm socket, although too big, JUST gripped - so probably 25 or 26 mm.
Take care not to damage the bulbs that were exposed when you took the knobs off ...
Step 4 - Remove Knob Surrounds
See -
Photo 4 = http://i156.photobucket.com/albums/t...heaterpic4.jpg
Photo 5 = http://i156.photobucket.com/albums/t...heaterpic5.jpg
The 'bucket' shaped knob surrounds are a press fit into the fascia, and held in place by the nuts - once the nuts are off you can start wiggling the buckets loose, and then out - avoid the temptation to prise them out with anything pointed - you're bound to damage the soft fascia ...
Once the knobs surrounds are out, you should see the bulbs, one located at the bottom left of the LH knob, and the other to the bottom right of the middle knob.
You'll also see the clear plastic 'light-guide' that reflects the light up to the various controls.
The old bulbs were easy enough to pull out with needle-nosed pliers, but tricky to get the new ones lined up to be pressed in to the contacts - take your time, don't rush it.
With the various bulbs replaced, carefully reverse the steps to re-assemble - I didn't see the need to tighten the nuts more than just snug.
Job done !
Sure enough, a question asked on this forum confirmed this, so armed with some ridiculously expensive 12v 1.2w bulbs purchased from Hellfords, I set about 'getting-in-there'
The bulbs WOULD have been cheaper from my MB dealer - part number 072 601 012 230, around £ 0.70 each
To clarify before we start, there are 5 bulbs in total - one behind the centre of each of the three knobs, and two further bulbs - one behind the middle knob, and one behind the left-hand knob.
These last two illuminate the knob surrounds, and the five-stage sliding fan speed control
Note - my car does NOT have A/C ...
Step 1 - Remove Knobs
See Photo 1 = http://i156.photobucket.com/albums/t...heaterpic1.jpg
They simply pull off - I'm using a pair of 'vice-grips', with a piece of rag to prevent damage to the knob.
Mine needed a fair old tug to get them off !
Step 2 - Knob illumination Bulbs
See Photo 2 = http://i156.photobucket.com/albums/t...heaterpic2.jpg
If it's just the bulbs behind the knobs that you need to replace, removing the appropriate knob is all you need to do - you'll see the bulb in the end of the tube that the knob rotated around. Pull the old bulb out, and press the new one in, making sure that the contacts on the new bulb line up with the socket - a bit fiddly.
To get to the other two bulbs - read on ...
Step 3 - Remove Hex Nuts
See Photo 3 = http://i156.photobucket.com/albums/t...heaterpic3.jpg
Not sure what size these nuts are, but my 27 mm socket, although too big, JUST gripped - so probably 25 or 26 mm.
Take care not to damage the bulbs that were exposed when you took the knobs off ...
Step 4 - Remove Knob Surrounds
See -
Photo 4 = http://i156.photobucket.com/albums/t...heaterpic4.jpg
Photo 5 = http://i156.photobucket.com/albums/t...heaterpic5.jpg
The 'bucket' shaped knob surrounds are a press fit into the fascia, and held in place by the nuts - once the nuts are off you can start wiggling the buckets loose, and then out - avoid the temptation to prise them out with anything pointed - you're bound to damage the soft fascia ...
Once the knobs surrounds are out, you should see the bulbs, one located at the bottom left of the LH knob, and the other to the bottom right of the middle knob.
You'll also see the clear plastic 'light-guide' that reflects the light up to the various controls.
The old bulbs were easy enough to pull out with needle-nosed pliers, but tricky to get the new ones lined up to be pressed in to the contacts - take your time, don't rush it.
With the various bulbs replaced, carefully reverse the steps to re-assemble - I didn't see the need to tighten the nuts more than just snug.
Job done !
