Hey all, I have an 88 Trans Am. When I turn on the A/C the red fusible link wire that runs along the fire wall to the blower motor heats up to the point that you cant touch it. I just replaced the High setting resistor and now have the high speed but the three lower settings all blow the same speed which seems higher than the high speed. I need to know how to check the resistor mounted on the a/c box and any suggestions as to why that wire heats up? Ive looked at all the wires and cant find any damage. thanks

 

First, high speed operation is controlled by the relay. The resistors drop blower speed. As you change blower speed from anything other than high you change from tap to tap on the resistor increasing resistance as you go towards the lowest speed. As you increase speed when you get to max the relay energizes allowing full voltage to the motor. Usually just removing the resistor and visually inspecting it will tell you if it's bad. As you will see it's just a few large coils of wire that form a high wattage tapped resistor. Make sure the coils are not broken loose to where they attach, otherwise thats about it. You can measure it with an ohmmeter and as you move from tap to tap you will see incremental changes in resistance. If it's OK, suspect a burnt speed selection switch, it's fairly common. Inspect all connections for signs of overheating and clean or replace connectors. When a wire gets hot it is sometimes caused by heat being carried through the wire from a bad connector or junction with resistance. The motor could also be drawing more current because of an obstruction or bad bearings.

 

Thanks for the info Danno, I did replace the high speed relay and now I will check the resistor pack, and your saying that if its visually good then its a probable speed selector switch in the a/c heater control? I was kinda figuring it that way but dont want to buy parts just to find it didnt fix the problem. thanks for the info again Juggie

 

Well, I pulled the heater AC control head apart and the 3rd highest speed setting lead was melted real bad so I will be replacing it. I will also be replacing the resistor pack as it is damaged. I will let you all know how it works out.