What to Do When the Upper Part of the Rear Window Defogger Doesn't Work?
2 Answers
If the upper part of the rear window defogger doesn't work, the entire glass may need to be replaced. Here is some relevant information about rear window defogging: 1. Reasons for non-functioning: This usually occurs in vehicles where the rear window has been tinted. During the tinting process, the heating wires on the rear window may have been cut due to the worker's lack of technical skill. 2. Defogging methods: (1) Use the heater to defog before driving. (2) Spray a defogging agent onto the inner surface of the car window and wipe it clean. This not only removes dirt from the glass but also forms a protective film to prevent moisture from condensing into fog on the glass. (3) Turn on the defroster switch for about a minute, and the fog on the rear window will disappear. Always wipe the rear window in the direction of the heating wires.
I encountered this situation last time too, it was really frustrating! There are mainly three scenarios when the upper half of the rear window defroster grid doesn't work. The most common issue is broken heating wires, especially when they get snapped by towels during car washes. You can wet a tissue and wipe a water mark on the window - if the area without response dries slower after turning on the defroster, it indicates damage there. Alternatively, using a multimeter to measure resistance gives more accurate results. Another possibility is aged roof wiring - my old car had oxidized connection wires inside the headliner. The most troublesome case is when the switch or control module fails - this isn't DIY-friendly, so I recommend consulting a professional technician. For safety, avoid makeshift repairs with tape or conductive paint as short circuits could cause bigger problems.
