Uneven clearing needs the pattern documented before an electronics fault is assumed. Local glass or heating-element damage and supply issues can produce different patterns; the control switch alone cannot distinguish them.
Photograph the clearing pattern safely
Take a stationary photograph showing the whole screen and note how long heating had been selected. Include recent glass replacement, visible damage and whether mirrors or rear-window heating work. Do not scrape or probe electrical connections at the glass.
Ask the glass installer or workshop to assess the correct circuits and installation. If the screen cannot provide safe visibility, arrange repair before driving. A narrow failed strip and a whole unheated section should be described differently, helping avoid an unnecessary body-control-module replacement.
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