Among the standard controls in modern cars, from the 1980s onwards, the rear window defogger or Defroster Button stands out as the most nomadic. It’s the automotive feature that has stubbornly resisted settling into a standardized location. Interestingly, while the icon for this function has become somewhat standardized, it’s conceptually inaccurate, especially considering how most rear window defrosters actually operate. Let’s delve into this automotive enigma.
Think back to the cars you’ve driven. Most controls follow certain conventions. Headlights are usually on stalks or dash knobs to the left of the steering wheel in left-hand drive cars. Turn signals are stalk-mounted. HVAC controls typically reside in the lower center console, often beneath the radio. But now, try to recall the location of the rear window defroster button in those vehicles. It’s highly likely no two cars placed it in the exact same spot.
Trying to find logic in the placement of the defroster button across different car models is an exercise in futility. Sometimes it’s clustered with the HVAC controls, sometimes near them but not quite, occasionally close to the driver, and often it seems haphazardly placed next to the hazard lights switch – a last-minute addition when someone realized it was missing. Even classic cars like the Beetle had a hidden switch under the dash, making it almost invisible. It’s as if automakers haven’t quite figured out where this defroster button truly belongs.
Personally, the most logical location for the defroster button is alongside the other HVAC controls. It performs a similar function to the windshield defogger, even if technically it’s not part of the main HVAC system. This brings us to the next point of confusion: the icon used for the rear window defroster button.
The contemporary, widely accepted icons for defogger switches are as follows: the left represents the windshield defogger, and the right, the rear window defroster button:
These icons use squiggly arrows to symbolize airflow, with the windshield icon also incorporating the shape of a windshield wiper’s sweep. The simple rectangle is meant to represent the rear window. This iconography suggests that rear window defrosters work by blowing air, similar to windshield defoggers.
However, for the vast majority of rear window defrosters, this is a misrepresentation. They operate electrically. There’s no air being blown onto the rear window to clear it. Instead, a network of resistive heating elements, essentially thin wires embedded in the glass, generate heat to melt frost or fog.
When a rear defroster is active, these wires become visibly warm and perform the defrosting work. Early defroster buttons actually used icons that more accurately reflected this heating element functionality:
These older icons featuring heating coil symbols are a much more truthful depiction of how rear window defrosters function. Yet, this more accurate icon has largely disappeared, replaced by the misleading “blowing air” symbol.
Ideally, the defroster button would feature the older, more honest heating coil icon and be positioned near the windshield defogger controls. This combination would provide both an accurate representation of its function and a logical location based on driver need – clearing windows for visibility. Grouping window clearing functions together simply makes the most sense.
What are your thoughts on this crucial, perhaps even critical, automotive design detail? Let’s discuss in the comments – let’s hash out the mystery of the defroster button once and for all!
