The blower motor resistor is an electrical component that is a part of the vehicle's heating and air conditioning system. It is responsible for controlling the blower motor's fan speed. A failed blower motor resistor can cause issues with the operation of the entire heating and air conditioning system.Keeping this in consideration, what are the signs of a bad blower motor resistor?
The most common symptom of a failed blower motor resistor is when the heater fan only runs at the highest speed setting (4 or 5) and doesn't work at low speeds. In some cars, a failed blower motor resistor can cause a heater fan to stop working completely.
Also, what causes heater resistors to burn out? Trent, one of the biggest reasons for blower motor resistors to have shorten life is actually because of faulty blower motor drawing too many amps, some times melting wires/plugs, heating up resistors shortening their life. Then they buy a aftermarket blower motor and again it keeps burning up.
Keeping this in consideration, what happens when a blower motor resistor goes bad?
If you have faulty blower motor resistor you may experience low airflow coming from the vents even when the fan is all the way on high. In some cases bad blower motor resistor may not even turn the blower motor fan as a result your fan will not work at all and there will be no air coming from the vents.
Can you bypass a blower motor resistor?
The blower resistor is connected in series with the blower fan. In the off state, the blower motor is disconnected from the power supply. In the highest speed state, the blower resistor is bypassed completely and the fan is connected directly to the car's battery, which allows maximum current through the motor.
How do you test a blower motor resistor?
Place one lead of the Ohmmeter on terminal 1 of the resistor. Place the other lead on terminal 2 and check against specifications. If this circuit is open, showing infinity on the Ohmmeter, the blower resistor must be replaced. Move the lead from terminal 2 to terminal 3 and check this reading against specifications.How much is a blower motor resistor?
The average cost for a blower motor resistor replacement is between $119 and $161. Labor costs are estimated between $47 and $60 while parts are priced between $72 and $101. Estimate does not include taxes and fees.Why does my air only work on high?
When a blower resistor fails, the highest fan speed usually is the only one that still works because it essentially bypasses the resistor and receives the maximum amount of voltage. When the resistor is working, it reduces the amount of voltage going to the lower fan speeds, so the fan runs slower.How do you test a blower motor?
How to Test a Blower Motor - Use voltmeter or ohmmeter to check for a blown fuse. If you find one, replace it.
- Start car and see if blower motor works. If fuse blows again, check for loose circuits.
- If the circuits are in good repair but the blower motor keeps blowing fuses, replace the blower motor [source: You Fix Cars].
Why is air not coming out of my vents?
The most common cause of low air flow through the vents in your home is blocked or dirty AC filters. Also known as vents, registers are the metal grates that let air flow from the AC ductwork into the rooms of your home.Why do fans stop working?
Check the Fan Fuse Like the circuit breakers in your house, these fuses are designed to break the electrical connection when too much electricity causes your fan to overheat. When the fuse melts, it breaks the connection and cuts power to the fan. Check the cord and the inside of your fan for this fuse.How do you know if a resistor is bad?
Resistors do not hold a polarity, so it doesn't matter which side gets the red or black lead. Check the reading to determine if the resistor is good. The two and a half million value resistor is good if the meter reads between 2,250,000 and 2,750,000 due to the silver tolerance band figure of plus or minus 10 percent.What does a cooling fan resistor do?
The cooling fan resistor is an electrical resistor that limits power to the fan in steps, so that the fan can operate at different speeds according to the cooling system's demands.What does a blower motor relay do?
The blower motor relay is the electrical switch that is used to supply the power for the vehicle's blower motor. The blower motor is the component responsible for pushing air through the vents of your vehicle's heating and air conditioning systems.Can a dirty cabin filter affect AC?
The most common symptom associated with a bad cabin air filter is poor air flow from the vehicle's interior vents. An excessively contaminated cabin air filter will not be able to filter the incoming air as effectively as a clean filter would. As a result, this will cause restricted air flow for the AC system.Why does my fan only work on high?
Most car manufacturers use a series of resistors to make the heater blower motor run at different speeds. And when one or more of these resistors burn out, you're usually left with only one heater blower motor speed—high. The resistor module is easy and inexpensive to replace.Can I bypass a resistor?
All current will bypass the resistor and travel through the short. The voltage across the 100Ω resistor is going to be zero. The 100Ω resistor is not impacting the circuit. The real world wire is going to have some resistance, and a tiny trickle of current will go through the resistor.What happens when a resistor burns out?
When a resistor breaks down, current typically flows through the burnt resistor without any resistance and thereby passes unchecked. Other components in the circuit may become damaged from the excess current flowing through.What causes a resistor to fail?
A fixed composition resistor normally fails in an open configuration when overheated or overly stressed due to shock or vibration. Excessive humidity may cause an increase in resistance. A variable composition resistor may wear after extensive use, and worn away particles may cause high resistance short circuits.Is there a fuse for the heater blower?
The blower motor is powered by a fuse-like device called a relay. If your heater or air conditioner does not blow air through the vents, this could indicate that the blower motor fuse has probably blown. While replacement is easy, the exact location of your blower motor fuse may vary from vehicle to vehicle.What controls the heater in a car?
The cooling system components that interact with the heating system are the coolant, thermostat, radiator, and water pump. The heater core is also utilized in the cooling system of the vehicle. The heater control valve is the device that controls the flow of the hot engine coolant through the heater core.Why is my car heater not getting hot enough?
Ken Mattson, owner of Len's Automotive in Bellevue, Wash., says a car heater can stop working for a number of reasons, including: A low antifreeze/water level in the radiator due to a leak in the cooling system. A bad thermostat that isn't allowing the engine to properly warm up. 
