Skip the auto shop - Our mechanics make house calls

Q: How Does a Car's Rear Defroster Work?

asked by on

How does a car's rear defroster work?

A: Most vehicles have an electrical grid on th...

Most vehicles have an electrical grid on the rear window that will warm the glass to clear fogging or frost. The rear defroster grid is applied to the inside of the glass by the manufacturer and actually conducts electrical current when it is turned on. There is typically a timer built in to the circuit that will automatically turn it off in 15 minutes or so, since it tends to get forgotten after the glass has cleared.

Larger vehicles like vans and SUV's commonly have rear defrost capability built into their rear A/C and heating systems. These function are much like the defroster in the front but using dedicated blower fan which ducts direct airflow onto the rear glass. Should you run into any problems with this system, have a professional mechanic diagnose your defroster to accurately repair your vehicle.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Save up to 30%

Get a quote

What others are asking

Q: AC not blowing cold air in 2008 Mazda3

Have a certified mechanic, such as one from YourMechanic, check the air conditioning system pressures for a low charge situation. The electrical side should also be inspected for blown fuses or broken wires. We recommend that you do not tackle...

Q: Difficult startup, low battery voltage, no oil pressure with windows, sunroof and locks malfunctioning

If the battery tested good, then I would suspect a problem with the alternator. The battery is basically just an electronic storage device that must be charged regularly by the alternator. In addition, there are a couple dozen modules aboard...

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...

Related articles

What Causes Hoses to Leak?
While the largest part of your engine is mechanical, hydraulics plays a significant role. You’ll find fluids at work in a number of different areas. Your car's fluids include: Engine oil Transmission...
P2428 OBD-II Trouble Code: Exhaust Gas Temperature Too High Bank 1
P2428 code definition A P2428 trouble code signifies that the PCM has detected a problem in the exhaust gas temperature sensor circuit in bank 1, which subsequently contains the number one...
How Much Does a Mechanic Make in Vermont?
Automotive technician jobs in Vermont have an average mechanic salary of $37k, with some mechanics earning a salary of $53k.