Thermostat or Final Stage Resistor?

[sjetton]

I have a 2003 325i (E46), just bought. It is cold here.... so I just figured out the heat does not work. All of the buttons light up correctly on the controls, and the fan does blow air, but it is cold air. I get NO heat (yes, the vents are set to the RED indicators).

Is this going to be a thermostat stuck in the open position, or the final stage resistor gone bad?

Thanks for any help...