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Why is My Car Defroster not Working

Your car's defrosting system is crucial for comfortable and safe driving, especially during the chilly winter. A failing defrosting system reduces visibility leading to hazardous driving conditions. There are two types of defrosters; front and rear defrosters.

Front Defroster

The front defrosters use the car's HVAC system to clean the dust and fog from the front side windows and the windshield. This system uses HVAC to draw in the fresh air and warm it up with the car's heater core. The warm area is then released via the vents to warm up the windows and windshield.

Why a Front Defroster May Fail

Clogged fresh air intake-located at the base of the windshield, the fresh air intake allows in fresh air helping the defroster to function. However, if dirt, leaves and debris clog it, it impacts the defroster's performance.

  • Stuck button- sometimes, the heating controls button or knob gets stuck. In such a case, try moving them front and backward to get them to the defroster position.
  • Vent problems- blocked vents will prevent the air from getting to the windshield. You can fix the issue by vacuuming the vents.

Other causes of a failing front defroster include a malfunctioning thermostat, a bad blower, low anti-freeze levels and a bad heater core.

Rear Defroster

The rear defroster uses electric energy to warm up the car's rear windows. A rear defroster starts working immediately after they are switched on, while a front defroster might take some minutes to heat.

Why a Rear Defroster May Fail

  • Broken tabs- the tab connects the defroster to the circuit and window. One of the tabs is positive, while the other is used as earth. If one fails, the defroster will also fail.
  • Broken grid- the grid runs through the rear window. If the grid wires are broken, the circuit opens. The defroster cannot operate from a break-forward point.
  • Old age- as they age, defrosters reduce their conductivity rendering the defroster inoperable.

If your front or rear defroster fails. Reach out to a professional technician for inspection, diagnostics and repair. If you need windshield defroster repair, Eddie's Northside Sinclair is your vehicle auto repair shop of choice!


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