How to Fix a Rear Window Defroster

How to fix a rear window defroster: If you find breaks or damage in the defroster grid, you can attempt to repair it using a rear window defroster repair kit.

Salman Chaudhary, Founder

How to Fix a Rear Window Defroster

A rear window defroster is a valuable feature, especially in cold weather. It clears condensation, frost, and ice from your rear window, improving visibility. If your rear window defroster isn't working correctly, this guide will help you diagnose and fix the issue.

Understanding the Rear Window Defroster

Before we begin, let's understand the basic components and function of a rear window defroster:

  • Defroster Grid: A thin grid of electrical conductors is embedded in the rear window. When activated, it heats up to melt frost and ice.

  • Control Switch: The rear window defroster is usually controlled by a switch on the dashboard, often with an indicator light.

  • Relay and Fuse: A relay and fuse protect the defroster from overloading and electrical issues.

Diagnosing the Issue

Step 1: Safety First:

  • Ensure the ignition is off and the vehicle is parked in a safe, well-ventilated area.

Step 2: Visual Inspection:

  • Inspect the rear window grid for visible damage. Look for cracks, breaks, or disconnected lines.

Step 3: Test the Control Switch:

  • Turn on the defroster using the control switch. Listen for a click from the relay, and check if the indicator light comes on. If not, there might be an issue with the switch or electrical connections.

Step 4: Check Fuses and Relays:

  • Locate the fuse box (often under the dashboard or in the engine compartment) and check the fuse related to the rear defroster. Replace it if blown. Additionally, test the relay or swap it with a known working one.

Repairing the Rear Window Defroster

Option 1: Repairing Grid Damage:

  • If you find breaks or damage in the defroster grid, you can attempt to repair it using a rear window defroster repair kit. Follow the kit's instructions for patching or reconnecting the grid lines.

Option 2: Check Wiring and Connections:

  • Inspect the wiring and connections between the switch, relay, fuse, and defroster. Loose or damaged wiring can cause issues. Secure connections and replace damaged wires.

Option 3: Replacing Defroster Elements:

  • If the grid is severely damaged or if the repair isn't effective, you may need to replace the defroster elements. This typically involves removing the rear window, which is a complex and costly procedure best handled by professionals.

Option 4: Seek Professional Help:

  • If you are unable to diagnose or fix the issue on your own, or if it requires advanced electrical troubleshooting, it's best to consult a professional mechanic or an automotive electrical specialist.

Preventative Maintenance

To avoid future issues with your rear window defroster, consider these preventative maintenance tips:

  • Regularly inspect the grid: Check the defroster grid for damage or wear during routine vehicle maintenance.

  • Keep the window clean: Clean your rear window regularly to prevent debris from damaging the grid.

  • Use defroster cautiously: Avoid using excessive force when scraping ice off the rear window, as it can damage the grid.


A functioning rear window defroster is crucial for visibility in cold and damp conditions. By following the steps outlined in this comprehensive guide, you can diagnose and repair common issues with your rear window defroster, ensuring that it continues to serve its essential function effectively. If you encounter difficulties during the repair process or if the damage is extensive, seeking professional help is always a viable option to ensure a safe and lasting fix.

How to fix a Rear Window Defroster
How to fix a Rear Window Defroster