A defroster is a part of your car that you may not think about every day, but you sure notice whether it’s working or not, come those cold winter days when you need to get rid of ice on your windshield. Whether your vehicle has a front windshield defroster or both front and rear window defrosters, here’s some basics to help you understand how these systems work.
What Defrosters are Designed to Do
Properly functioning defrosters are designed to get you on your way quickly and with full visibility. When the weather is cool, droplets of water will form as condensation on the vehicle’s windows, due to the temperature variance between the air inside your vehicle and the air outside. When the temperature drops, the condensation turns to a coating of frost or ice, which needs to be removed before you can drive.
Types of Defrosters (Vents &. Wires)
Your front defroster operates on a venting system in your dashboard. The same fan and blower motor that operates your air conditioning, also circulates warm air through these vents to defrost the windows. Make sure the dashboard vents are open, and set your vehicle to the defrost setting.
The rear defrost system is delivered through a series of electrical wires running across the rear window. If your vehicle has a rear defroster, simply depress the rear defrost button and almost immediately you’ll notice the dissipation of condensation or frost moving outward from the wires until the whole window is clear.
How Defrosters are Activated
Front defrosters operate when coolant reaches a certain temperature to open the thermostat, and could take a couple of minutes. Hot water moves though the heater core, and a fan pushes the resulting warm air through the vents and onto the front windshield. Warming up the inside of the vehicle also removes condensation and dampness, creating a more comfortable environment for passengers.
The rear defrost is electrical, and starts to work as soon as you turn on your vehicle and set the rear defrost button. It’s becoming commonplace for vehicles to incorporate electric defrost along the edges of the front windshield and side view exterior mirrors to improve visibility.
Common Issues with Defrosters
You often won’t notice a problem with a defroster until you need it and it fails to work. This can happen for a variety of reasons:
- Buttons or knobs that are stuck or have stopped working. May need replacement or repair;
- Blown fuse: When a circuit is overloaded, it may blow the fuse that connects to the defroster, the fuse can be tested and replaced by a professional;
- Missing terminal edges on the window: This may be caused by tinted windows that have started cracking or tint that has come off;
- Lack of antifreeze: When the antifreeze level is too low, the car may not heat properly or allow the defroster to work;
- Frayed wires: Wires that are disconnected or frayed will prevent the defroster from working;
- Clogged vent: When a vent is clogged with dust and debris, the air cannot flow through to warm up the windshield.