When defrosting the front windscreen, is it necessary to have the A/C system running ?
(I know that the fan has to be running and directed at the screen)
The user hand-book seems to imply that it is necessary.
2006-09-18 04:47:31 · 6 answers · asked by Anonymous in Cars & Transportation ➔ Safety
Thanks fellas !
I do know that the A/C comes on automatically when the blower is set to screen.
I just wondered about the necessity for doing this.
2006-09-18 04:57:00 · update #1
It depends if you are defrosting (i.e. heating the screen to melt frost on the outside) or demisting (evaporating condensation from the inside).
If you are defrosting the screen, you want the air-con off, and the heat on. This puts the maximum heat onto the screen to melt the frost. On some versions of Focus you can use the heated front screen to do this instead of using the heating/ventilation/air-con (HVAC) system.
If you are demisting the screen, then you normally want the air-con on, as the air-con dries the air as well as cooling it, and the dry air (even though it is cooler) is better at evaporating the condensation from the inside of the screen.
However in cold conditions you can have air that is too cold coming from the air-con, which freezes the condensation rather than evaporating it.
On warm humid evenings you may find that using the air-con to cool and dehumidify the cabin cools the windscreen so much that condensation form on the outside of the glass where the air hits the screen on the inside.
2006-09-18 08:48:06 · answer #1 · answered by Neil 7 · 0⤊ 0⤋
The A/C is automatically ON when the defrost is selected. This dries out the air that you are forcing on the windscreen.
2006-09-18 04:51:25 · answer #2 · answered by fstopf4 4 · 1⤊ 0⤋
No, not at all. Just press the windscreen "heater" button (there's one for the windscreen and one for the back window). You don't need to turn on either the A/C or the fan.
2006-09-18 04:52:35 · answer #3 · answered by Colin S 3 · 0⤊ 0⤋
I would not think so the fan should stop the condensation in the inside of the car unless the a/c is to exstract the condensation from the inside of the car
2006-09-18 04:51:38 · answer #4 · answered by jonnaymomo 2 · 1⤊ 0⤋
The AC compressor will operate on any setting except vent. So, in answer to your question, no.
2006-09-18 04:52:08 · answer #5 · answered by Anonymous · 0⤊ 0⤋
not all focus have a heated screen if you have one just use that if yuo dont use ac it will clear quicker as ittakes mosture out of air
2006-09-18 05:01:34 · answer #6 · answered by kelly r 2 · 0⤊ 0⤋