Resistor interior blower for different automobiles
Other Heater/cooling system auto parts
Your Blower motor resistor worn out? » Read more about common malfunctions • Repair • Replacement manual
The blower motor resistor is a small component, controlling the rotation speed of the interior fan motor. This blower is used for the air conditioning as well as for the general interior ventilation.
When the blower is on strike
An exact control of the interior ventilation is standard in a modern car. The airstream, leading exterior air into the car interior or causing the air to circulate in the interior ensures clear windows, a comfortable climate and fresh air during driving. If the blower fails these functions are no longer guaranteed. Not only is this a nuisance, but can in case of fogged up windshields cause a dangerous situation.
The malfunction of a failing blower can be isolated very quickly with a bit of expertise. Furthermore, the blower's switch will betray where the fault probably lies:
- The blower fails completely as a result of a defective motor or a ruptured cable
- The blower is functioning only at several levels is the result of a defective switch
- The blower only functioning at highest level is the result of a defective resistor
The following defect is also fatal: the blower runs slowly, but the blower motor is smoking excessively. This is very dangerous as the developing gases are poisonous and the defective motor might cause fire in the car. The blower motor must be switched off and disconnected to prevent it from automatically engaging again.
Blower motor resistor function
Technically the blower motor resistor is a very simple component. It conducts the current between battery and blower fan via several resistors which are opened or closed by the turn or rocking switches in the dashboard. If no resistance is switched on between the electric supply and the blower motor, it runs on its highest level. The fan runs slower when the switched resistance is higher.
The resistor's function makes a diagnosis simple: a resistor converts the added energy into heat and only partly transmits it to the electric circuit. The separate resistors are placed in a row. The exhaust heat radiating from the separate resistors according to working level, affects the other resistors as well. Sooner or later, this will cause the resistors to burn up. If that happens, the fan only switches into its highest level as no resistance is active and the full electricity supply is being transmitted.
Blower motor resistor repair
A blower motor resistor is an electronic component. It consists of a housing, control electronics and resistors. These are placed in a row and incorporated into a resin block. In case of a defect, the resistor burns out, destroying the entire component. Repair of a blower motor resistor therefore makes no sense and is practically impossible. The only way of mending the fault is replacing the entire component. The blower motor resistor is placed right next to the fan motor and is connected to it by a simple plug. The fan motor is situated in the foot space of a car behind the dashboard cover. Its position can vary considerably, depending on the car model. Very often the fan motor can be found in the foot space of the passenger's seat under the glove compartment. In most cars, disassembly is very easy: the cover has to be removed. The fan motor is often fixed to a mount by a swivel lock. By twisting the motor, it will loosen from the mount and can be taken out.
Mind the quality
As an electronic component, the blower motor resistor has a higher price than simple spare parts. It’s worth mentioning that these parts are absolutely cheap even coming from brand manufacturers. For electronic components under constant strain such as these, quality is very important. Only branded quality guarantees the resistor to reliably function within a reasonable life span.