The thin horizontal lines across a rear window are easy to overlook until a scraper catches one. On many cars, those lines form the electric demister. Cleaning the glass should remove the haze without disturbing the equipment attached to it.
Start by checking your vehicle’s handbook. Factory glass, replacement glass and aftermarket tint may have different cleaning requirements. A product that is suitable for plain glass is not automatically suitable for the film covering it.
Make the cloth do the work
Park safely, switch the demister off and let the glass cool. Remove loose grit gently before wiping; dragging a gritty cloth across a surface can scratch it. Use a clean, soft cloth and a compatible glass cleaner in a modest amount. Applying cleaner to the cloth helps control drips around trim and electrical connections.
Work in small sections with light pressure. Turn the cloth to a clean face as it collects dirt, then use another clean cloth for the final wipe. Inspect the result from outside as well as from the driver’s seat: a patch that looks clear from one angle can still leave glare at another.
Ford’s Fusion/Mondeo owner information specifically warns against razor blades or other sharp tools on the inside of the heated rear window. Treat stubborn sticker adhesive as a separate problem. Check the approved removal method rather than escalating from a cloth to a blade.
Keep cleaning and fault-finding separate
If one strip remains misted while neighbouring areas clear, note where it happens and arrange an inspection. That observation can help a technician, but it does not prove that cleaning caused the fault. Avoid scratching the line to test it or applying an improvised conductive repair.
Before driving, restore a clear rearward view and put the cleaning equipment away. Good visibility is the useful outcome; a stronger chemical or harder scrub is not evidence of a better clean.