How do you defrost a rear window?
Reviewed by the Skyview Auto Glass technical team — NWRD-, ASE- and DINITROL-trained technicians · Updated November 2026
Quick answer
Press the rear defrost button — the one shaped like a rectangle with wavy arrows pointing upward — and the heated grid lines on the back glass warm up to clear condensation and frost. Most systems switch themselves off on a timer after a few minutes. Never scrape the grid with a razor, or you will cut the lines.
How to defrost the back window
The rear defroster does the work. Give it a minute rather than reaching for a scraper.
- 1
Find the button
Look for the button with a rectangle and wavy arrows pointing up, usually on the climate panel. It lights when it is on.
- 2
Switch it on
Press the button. The heated grid lines across the back glass warm up and begin clearing condensation and light frost.
- 3
Let the timer run
Most rear defrosters switch themselves off after a few minutes. If the glass is not clear, run it again rather than scraping.
- 4
Clear heavy snow first
Brush heavy snow off the back glass before you switch the defroster on, so the heat reaches the glass instead of melting a thick layer of snow.
What the rear defroster does and does not do
- Clears condensation and light frost from the inside and outside of the back glass.
- Switches itself off on a timer on most vehicles.
- Does not melt thick ice or heavy snow — brush that off first.
- Stops working if a grid line is cut by a scraper or a tint removal gone wrong.
- Works only where the grid lines run, so a damaged line leaves a clear strip uncleared.
Never scrape across the grid lines
The rear defroster depends on the grid of heated lines bonded to the glass. A razor or a hard scraper pulled across the lines cuts them, and the defroster stops working in that strip. See our guide on rear defroster lines not working.
More questions about rear defrosters
What does the rear defrost button look like?
A rectangle with wavy arrows pointing upward, usually on the climate control panel. It lights up when the rear defroster is on.
How long does a rear defroster take?
Most clear condensation and light frost within a few minutes, then switch themselves off on a timer. Heavy ice or snow needs to be brushed off first.
Why is my rear defroster not working?
A cut grid line is a common cause, often from a scraper or a tint removal gone wrong, and it leaves a strip of the glass uncleared. See our guide on rear defroster lines not working for how to find the break.
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