Well there goes my fun...

[JaM Customs aka mprete]

yea i would check the fuses under the hood if you havent done that already, but also try to find out if the other settings work on your air. you said its stuck on defrost? will it go off? the sound you are hearing is probably the blower motor being on all the time if its stuck on. what kind of car it is? year make model

[Parentnoia]

It does turn off. And it's a 1998 Ford Escort SE 2.0

[JaM Customs aka mprete]

well first off the easiest this to go is check to make sure you have power at the red and yellow wires with a test light or a dmm and then check to make sure your black ground is good. if both of those are good then your hu got fried. if there is no power then trace the wires back to their fuse. but start with checking your power and ground

[Parentnoia]

Well the radio itself isnt ground directly to the car. It's connected to the ground wire on the harness.

And how would I test for power? Connect one end to the red and then to the yellow or wise versa?

As for a DMM, the closest I have is an analog one that I have no idea how to use...

[OrionStang]

Go buy a simple test light at the dollar store. Should have an alligator clip on one end and a probe on the other with a light in the middle. Ground the clip and probe the red and yellow wires on the headunit. If the light doesn't come on, theres no power.

[Parentnoia]

I have a light, I just dunno how to use it. Thanks for the info. I'll test later when I take my girl to work (too lazy to go out in the cold to test it right now).

[uhoh_45]

does your deck have a fuse on it.........?

[blackrosetiger]

Lol dude you just unhook the negative terminal??? and make sure its not touching the battery

WRONG you always, always, ALWAYS remove the positive terminal. If you just disconnect the negative terminal that terminal can touch ANYTHING metal and ground out.

[Parentnoia]

does your deck have a fuse on it.........?

Yes and no it's not blown. That was one of the first things I checked.

[casemods]

stupid question but did you check the power wires going to the head unit and the fuse on teh head unit itself/inline fuses before the head unit?

power test the wires to make sure they are getting power.

if not, then it's def a fuse...and my 96 has a fuse on the head unit area so your 98 should. but not too sure about fords.