Skip the auto shop - Our mechanics make house calls

What Does the Defrost Indicator (Front and Rear) Warning Light Mean?

What Does the Defrost Indicator (Front and Rear) Warning Light Mean?

Most of us have noticed our car windows all fogged up on cold mornings. This is caused by moisture trapped inside the vehicle which then condenses into small drops of water on the glass. If the air outside is colder than the inside, the droplets will form on the inside of the glass. As soon as you enter the vehicle, your breath will add heat and more moisture to the air which fogs the windows up even more. The wipers can’t help clear up the fog on the inside of your car, for that you will have to use the defrost setting on the climate control. For the windshield, vents located right below the glass direct the air to the window to clear it up. Commonly the air conditioning will engage to help get rid of the moisture as the A/C dries the air before it goes through the air vents. The drier air is absorbs more moisture and clears the window faster than with normal air. On the rear windows, wires are placed on the glass in a grid pattern. These are the black lines commonly found on the rear windows. Electricity gets sent through the wires which generates heat and clears the moisture from the window.

What the defrost indicator light means

Whenever the light is illuminated, the defroster is turned on. The symbol for the front is a curved window, while the rear is rectangular. While you are defogging the windshield, you may not be able to get air out of the normal vents. This way all the air is forced up to try and clear the moisture so that you can drive safely. Any flashing with these indicators means a problem has been detected. You will need the help of a professional with a diagnostic scan tool to read the code saved on the computer. This code will help identify any issues that are present. Depending on the problem, you may or may not be able to use the defroster. Some vehicles with automatic climate control can turn on the defroster when the humidity gets too high. This will help keep you windows clear and you shouldn’t have to do anything. If your vehicle has this feature it is normal for the light to illuminate occasionally while you are driving.

Is it safe to drive with the defrost indicator light on?

The defroster keeps your vision clear while driving and without it, you could have a really difficult time seeing out of your windows. If the edges of the windows start to fog up, turn on the defroster for a little bit before the fog covers the whole window. Even with a malfunction detected, so long as you can clear up the windows, you can still use the car normally.

If you are experiencing any issues with your defroster, our certified technicians are available to help you diagnose any problems.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
Icon-warranty_badge-02

Skip the repair shop, our top-rated mechanics come to you.

At your home or office

Choose from 600+ repair, maintenance & diagnostic services. Our top-rated mechanics bring all parts & tools to your location.

Fair & transparent pricing

See labor & parts costs upfront, so you can book with confidence.

12-month, 12,000-mile warranty

Our services are backed by a 12-month, 12,000-mile warranty for your peace of mind.

Get A Quote

Need Help With Your Car?

Our certified mobile mechanics make house calls in over 2,000 U.S. cities. Fast, free online quotes for your car repair.

GET A QUOTE

More related articles

The Traveler’s Guide to Driving in Malaysia
CraigBurrows / Shutterstock.com Malaysia is a popular destination for many tourists today. The country has amazing sights and attractions that you will want to explore....
Veteran and Military Driver Laws and Benefits in Idaho
The state of Idaho offers a number of benefits and perks for those Americans who have either served in an Armed Forces branch in the...
What are the Car Pool Rules in Hawaii?
Hawaii is widely regarded as a land of vacation and relaxation, and as such, its scenic roads and routes are far better known than the state’s freeways. But, as with all...


Related questions

Q: Cars stalls when the AC is turned on.

A seized AC compressor can stall your engine when you turn on the air or defroster because it sends a signal to engage the clutch on the compressor, which causes more resistance than normal. But there are switches that level...

Q: Indicator lights of park and drive are on. The engine don't want to start with the lights on.

Hi there. The orange gear light that appears on the dash is the warning light for the transmission. First check the computer (ECM) and see if there is any stored codes for the transmission or transfer case (if your vehicle...

Q: Air control knob staying in one position

There is a possibility that the mode door for the vent, floor, defrost blend door is broken in the evaporator case, or that something fell into the case through the defroster duct and is binding the door. The dash panel...