Heater resistors contain controls that determine air settings. If the airflow exceeds a predetermined amount, the heater resistor reduces airflow through the vents via wire coils. Each coil is responsible for one particular speed setting: thinner coils correspond to higher air settings and offer the least resistance or the least opposition to the flow of electric current; this allows the blower fan to rotate faster. Thicker coils, on the other hand, correspond to lower air settings and force the fan to rotate more slowly.
If the heater resistor fails, the interior blower motor only functions at its highest speed and cannot decelerate; replacing the resistor typically corrects this problem.
Overheating is the main cause of failure; the mechanical resistance to the motor rotation can cause excessive current that can overheat and prematurely damage the resistor, for example, when the fan blade is jammed by an object or when the motor bearings are worn out.
All products are catalogued on MAM Autocat+ within two sections:
• Cooling & Heating – Radiators, Heaters, Coolers
• Cooling & Heating – Switches, Sensors, Cooling & Heating
Log on to the F:Drive or call your local FPS branch to place an order. For more information, please contact your local FPS representative.