Heater, Climate control

Okay so my bf's heater was on the blitz then eventually went out. It heats but does not blow air. He replaced the fan and switch but it still doesn't work. Fuse is fine too. So I pulled out the climate control section and found two of the 4wires were corroded and melted in plastic of the connector. I pulled the wires from the plastic, connected the good wires then stripped and held the bad wires directly. Still nothing. It sounds to me like it may be a vacuum hose because when the heat is adjusted it makes a pffffffff noise. I am guessing the dash is going to need to be taken off to find the problem but thought I'd see if anyone had any advice or suggestions first? Or at least some kind of confirmation for my bf. He thinks I'm just lookin for an excuse to tear something apart....but thats only part of it.

If the fan isnt coming on it's 1 of 3 things...

Fan rheostat switch...

Inline resistor (most common)

Or the fan is shot...

Based on the melted wires (did you meter them as well?) I would say the resistor burnt up with the wires...

Thanks for your response! But..... Whats the inline resistor? Also after removing more of the climate control he found loose parts laying inside. Three springs and a round dial?

Oooo...never mind! He showed me the parts and I could see where they are soppose to go to. It's the switch the wires connect to that controls the vacuums. So...Off to go get another part! Thanks again!

The resistor allows proper restriction of power based on the reheostat control..(fan speed switch)