Q: When you turn on the defroster/defogger, is the windshield supposed to defog instantly?

asked by on

In the morning when the windshield is fogged up, when you turn on the defroster is it supposed to instantly clear the windsheild or will it take a few minuets to clear?

My car has 12100 miles.
My car has an automatic transmission.

This can actually take a few minutes - and depends on the temperature and level of moisture in the air inside as well as outside the vehicle. Two things happen when you use "Defrost/Defog". The air needs to be heated, and the air needs to be "dry" (low moisture content). Engine heat provides the heated air (through the heater ducts), and the AC system takes moisture out of the air inside the car while cooling it. But then this cool air requires more heat to help defog. So, as you can see - the engine has to heat up, and the AC has to work a few minutes to dry out the air inside the car. Great question!

Was this answer helpful?
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
  1. Home
  2. Questions
  3. When you turn on the defroster/defogger, is the windshield supposed to defog instantly?

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: How do you use the defroster?

It’s important that you have a clear view out of the windshield and all the other windows in your car. Of course, it seems to take very little to fog them up, and during the winter, ice and freezing rain...

Q: Purge valve canister

Hi there. In most cases, the purge valve needs to be replaced. It's due to rough idle or issues with emissions. If not replaced in a relatively short period of time, it can cause additional problems with the EVAP system...

Q: Car shaking when applying brakes and going slow. Check Engine Light is on and engine idles roughly.

It sounds like you may have a vacuum leak on your car. Check all vacuum lines and make sure they are in good condition and connected. If you don't see a leak you can spray some carburetor cleaner on the...

Related articles

How Long Does a Heater Control Valve Last?
Keeping the right amount of coolant in a car is essential in keeping the engine at the right temperature. Failing to have the right amount of coolant or even bad elements...
P0052 OBD-II Trouble Code: HO2S Heater Control Circuit High (Bank 2 Sensor 1)
P0052 code definition HO2S Heater Control Circuit High (Bank 2 Sensor 1) What the...
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...