Thread: defroster won't work

Originally Posted by Underdog

What about cars that didn't come with A/C from the factory....does that mean that they also didn't come with defrosters????? :o

They have defrosters, but it's just ducts pointed at the windshield. If the windshield is the same temp as the air inside the cabin, the air against the windshield won't cool drastically and dump it's water vapor on the first solid object it comes into contact with, the inside surface of the glass. You have to wait for your coolant temp to warm up in order to get any warmed air out of the ducts of course. The air passing through the heater core also drops in relative humidity as it's temp increases, meaning it can pick up water vapor as it moves from the duct across the windshield. Then dump it on another window in the car after it cools again haha

if your a/c comp works with the botton then just turn it on when you want to defrost.