Flash (AS3) Movieclip Rotation

Flash (AS3) Movieclip Rotation

if (rotCW)
{
tramp1.rotation += 3;
if (tramp1.rotation = 90){
tramp1.rotation += 0;
}
}
I'm trying to make it so that if the movieclip's rotation is 90, its
rotation speed is 0. But every time I press the ' key (which triggers
rotCW), the movieclip's rotation just goes to 90.