Is there a common point of failure?: Coolant warning light and heater fan controls

[nekomata]

Hi,
I have an N-reg C180 (w202), and have recently had 2 issues spring up either together or within a short timeframe:

- The coolant warning light has come on. I've checked the coolant level and everything looks fine, plus I've driven from Reading to Edinburgh and back without issue, so I actually suspect an electrical fault rather than an actual coolant fault.

- The fans for the internal heater aren't operating. In long journeys I can feel the heat near my legs, so I think the heater itself is working, but the fans aren't blowing it up towards the windscreen. I've also noticed that the lighting for the heater directional dial is working, but that there is no lighting for the fan speed dial, so I'm wondering if the problem may be with the fan controls rather than the fans themselves.

Now, I remember that last time I had multiple seemingly unrelated issues spring up at once, it turned out that I needed to resolder a common relay. As such, I was wondering if anyone knows of a common point of failue for the above 2 issues.

Thanks!

 

[Ted]

Something rings a bell that the lightcovers both coolant and washer fluid. You could check your washer fluid is topped up.
The heater sounds like worn brushes or possibly a faulty regulator. Try a good firm slap near the heater motor - this may be enough to dislodge the brushes so they work for a short while. Otherwise it is testlight out and check fuses and wiring.
The light in the switches is a common problem. Pull the knob off - it will be tight, and the bulb can be replaced. It is a bit fiddly - you can use a straw or rubber tube over the bulb to remove and refit.