I took this out from the box of the air conditioner unit there is a plug with 4 terminals that connects to this, the contacts are rusty and one of them is damaged on the terminal, i wonder what does it do.

that is the series resistor pack, it is used to control the speed of the ventilation fan. basically it has a grid of resistors, as you change the position of the fan switch it changes the amount of resistance applied to the 12v feed to the fan motor and hence alters it's speed

it has a cut off switch in the midle of the 4 coils, posibly thermal, what does that switch do? does it cut the fan, cus my fan hasnt been working for a while and i was thinking it was something serios.

anyway, if what you say is true, i can make my own, im pretty shure i can grab a couple of resistors and work my magik and have the multiple fan speeds working again (before the fan only had one speed, the faster one and now it doent work)

question, if i take it off, would the fan work on the highest speed (the one that doent need resistors)

yes, it should work without the resistor plugged in, but only on the highest speed setting

so that mean i have a damaged resistor pack, wich i can buy / built and also a problem with the line going to the fan (i know the fan works because it used to com in an ou interminently before) curious thing is i let the car without batery while i was fixin the alternator my fan wast working and then when i put the alternator and the charged batery it worked, but now it doenst work anymore same as before, worked, then worked intermitently, then worked sporaticaly, now dont work

any thoughs on that ?

erm yeah, it's broken

I made a little hole in the unit and ran a cable for the 2nd pin to bridge the damaged connection and it works.

I noticed that the coils that serve as resistor get very hot, also noticed that the cable goin into the unit has heat damage as well as the terminal conected to the fan motor.

seems to me that the re is a fault wiring causing a bigger load.