I. What is blower motor resistor
A blower motor resistor is a component of a vehicle's heating, ventilation and air conditioning (HVAC) system. It plays a key role in controlling the speed of the blower, which circulates air through the vehicle's cabin. The working principle of the blower motor resistor is as follows: when you adjust the speed of the fan in the car, you are actually adjusting the current that the fan motor resistor allows to reach the fan motor. The higher the fan speed setting, the greater the electrical flow allowed through, and the faster the fan motor speed. The fan motor resistor has a number of coils with different resistance values, corresponding to each speed setting of the fan. Due to their resistive nature, fan motor resistors generate heat during operation. It is usually located in the airflow of the fan in order to cool and prevent overheating.
Here are some general specifications for blower motor resistors:
- Resistance Values：The primary function of the blower motor resistor is to control the current flowing to the blower motor and thus adjust the speed of the fan. It does this by offering different resistance values, which are typically calibrated for the different speed settings on the HVAC system.
- Number of Speed Settings：The number of different resistance values or speed settings provided by the resistor can vary. Most systems have four or five different speed settings, but this can vary depending on the vehicle.
- Connector Type：The blower motor resistor will have a specific type of connector to fit the wiring harness in your vehicle.
- Material：The resistor is typically made of a ceramic material, which can withstand high temperatures. The actual resistive element is often made of a special type of wire or thin metal strip.
- Mounting Type： The resistor is usually designed to be mounted into the HVAC duct, close to the blower motor. It will have mounting holes or slots that match up with the corresponding parts in the HVAC system.
- Driven Configuration：The resistor is usually part of a low-side driven configuration, meaning it controls the ground side of the blower motor circuit.
II. Signs of blower motor resistor damage
- The blower resistor is mainly used to control the blower speed, if the blower resistor is damaged, then the blower speed is the same in different gears.
- After the blower resistor is broken the airflow control knob loses its speed control function, which will cause the airflow to not be adjusted. The blower motor only runs at some speeds, not all.
- There is no 1234 gear, only one airflow.
- The blower motor overheats, there is excessive heat or even smoke at the air outlet, or you can smell burning plastic or electrical insulating material.
- The blower makes an unusual noise, screeching or wailing sound
III. Causes of blower motor resistor damage
Over time, the blower motor resistor may fail due to normal use and wear. Frequent fan speed adjustments may also accelerate resistor wear.
Caused by a short circuit in the compressor or control circuit, or a faulty condenser motor, compressor electromagnetic clutch, or evaporator motor;
Automobile air conditioning fan fuse does not meet the requirements, the current value is small, there is a short circuit in the air conditioning system, and the compressor is overloaded can also lead to damage to the blower resistor;
Excessive current is not good for heat dissipation, the internal resistance of the blower is too large, due to the flow resistance current is too large and loose, the service life of the resistor is shortened, it is recommended to replace the blower.
Moisture may cause a short circuit inside the resistor or cause corrosion of the resistor. If there is moisture inside the vehicle, it may cause damage to the resistor.
IV. Cost to replace blower motor resistor
Before replacing the blower motor resistor, you need to know where it is located. The location of the blower motor resistor varies depending on the make and model of the vehicle, but it is usually located in the vehicle's heating and air conditioning system near the blower motor. In many vehicles, the blower motor resistor is located under the passenger side dashboard. It is usually mounted in the HVAC (heating, ventilating, and air conditioning) ductwork near the blower motor itself, as it works in conjunction with the blower motor. It is usually a small rectangular part with a wire plug on it. However, in some vehicles it may be located in a different location, such as under the hood or behind the glove box, and in some models it can be a bit difficult to access.
And in some vehicles, the blower motor resistor may be located in a more difficult to reach area, which can add to the cost of labor due to the extra time required to do the job. So the cost of replacing a blower motor resistor varies depending on the make and model of the vehicle and where you live. In general, the parts themselves usually cost between $20 and $100. Labor costs for installation range from $50 to $200, depending on the complexity of the installation and the mechanic's labor rate. Therefore, the total cost can range from $70 to $300. It's a good idea to get some quotes from different service centers or mechanics to make sure you're getting a fair price.
IV. The importance of resolving blower motor resistor failures
- Maintaining Comfort in the Vehicle
The blower motor resistor controls the speed of the fan and is critical in regulating the temperature and airflow inside the vehicle. If the resistor fails, the air conditioning and heating system may not work properly, which can affect passenger comfort.
2. Ensure Clear Vision in Cold Weather with Window Defrosting
In freezing weather or wet conditions, the blower motor resistor can help clear windshield fog or defrost the windshield by adjusting the speed of the fan to ensure safe driving.
3. Preventing Further Damage to the HVAC System
If the resistor failure is not repaired in time, it may cause the blower motor to overheat or even burn out, resulting in further damage.
