Defroster fogs up windows

nissan
200sx

#1

I have a 95 Nissan 200SX SE-R and I’ve recently started using my defroster again as the weather is changing. I’ve noticed no matter if I turn my defroster to as hot as it will go or as all the way to cold it does exactly the opposite. However, when I engage the A/C, it defrosts the windows. Someone suggested it was the heating coil going out but I sure feel plenty of heat coming out. Anyone have any ideas?


#2

Move your air direction switch from Recirc to Fresh Air.


#3

You may have a pin hole in your heater core. Defrosters work best when the the AC is on (on most cars the AC goes on automatically when you turn on the defroster because it removes moisture from the air). The hole may be small enough that the AC is able to remove the moisture. Try turnig on the heater without the AC and see if you can smell antifreeze (sweet smell) coming from the vents.


#4

As suggested, it looks indeed like you have a small leak in your heater core. This has happened to me on a Chevy Impala and a Ford Granada. It is usually accomopanied by a sweet currie-like smell (hot antifreeze), and the windshield will be somwhat sticky. When the leak gets bigger you will have a shower of hot antifreeze coming up the defroster vents. With the A/C on the air is directed over the A/C coil instead, and the dry cold air will not cause fogging. When I described the symptoms(with the Impala)over the phone to my mechanic, he told me exactly the problem and the price to fix it.


#5

That worked, thanks! Who knew it was such a simple problem!