What does the blower motor resistor do? The blower motor resistor is responsible for
controlling the blower motor speed
. In the past, this was done by varying the voltage supplied to the blower motor. In newer applications, the blower motor resistor is actually a solid state module that sends a varied signal to the blower motor.
What happens when blower motor resistor goes out?
Power to the blower motor is fed through the blower motor resistor, so if it fails or has any issues
power can be cut off to the motor
. A blower motor without power will not be able to produce any air pressure, and as a result the heating and air conditioning system will be left with no air coming from the vents.
How do I know if my blower motor resistor is bad?
If you try to increase the air pressure and you feel no difference in the pressure blowing
, then your blower motor resistor may be failing. A damaged blower motor resistor will work on one fan speed which may not be enough to keep the inside of your car cool or warm enough.
Will a blower motor work without the resistor?
Without any power, the motor won't run
. As a result, the blower fan stays still and silent, and no air blows out of the vents. There are instances where a bad resistor will prevent the current from reaching the blower motor altogether.
How can I test my 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 does it cost to replace blower motor resistor?
To replace the blower motor resistor, it would cost you anywhere between
$50 to$150
– this includes the cost of equipment and labor. However, by doing it yourself at home, you can save up to $70.
Can a bad blower motor resistor cause no AC?
No Air Coming From Vents
The blower motor resistor controls the power to the system's blower motor. When it fails, it can cut off all power to the motor.
What are the symptoms of a bad blower motor?
- Poor or Airflow from Air Vents. This will be the first and most obvious sign your blower motor has a problem. …
- No Airflow At All From Vents. …
- Skyrocketing Energy Bills. …
- Strange Noises When You Turn on the Heat. …
- Overheating Blower / Weird Smells.
Is there a fuse for blower motor?
Fuse Protection
To protect the blower motor power circuit,
a 20-, 25- or 30-amp fuse is usually located in the fuse panel under the dash
. The rating of the fuse will depend on the vehicle application and how much power the blower motor requires at full speed.
Can a bad blower motor cause no heat?
Problems with Your Blower Motor or Blower Motor Resistor
Without it, there's no circulation of air—hot, cold, or otherwise. The blower motor resistor is the part that controls the fan speed of the blower motor.
Both of these components can fail, resulting in the heating system simply not working
.
How do you know if a resistor is bad?
A good resistor should test within its rated range.
A bad resistor will either show infinite resistance or a measurement far higher than its rated resistance
. In either case the resistor is no longer functioning properly.
What is the difference between blower motor and blower motor resistor?
The blower motor resistor is responsible for controlling the blower motor speed
. In the past, this was done by varying the voltage supplied to the blower motor. In newer applications, the blower motor resistor is actually a solid state module that sends a varied signal to the blower motor.
How long should a blower motor resistor last?
The blower motor resistor is designed to last
for the car's lifespan
. In most cases, these resistors will wear out long before the car does. Usually, the wear that the blower motor resistor has is due to the constant use that it gets and the heat that it is exposed on a regular basis.
Where is the blower resistor located?
The blower motor resistor is usually extremely easy to access, but the hard part can be positioning your body inside the car to remove the part. The resistor is
at the bottom of the HVAC housing or just behind the glove compartment
.
Why is my blower fan not working?
If you see or hear the fan turn on, your blower motor is not the culprit. If the fan does not start,
you have a wiring issue (circuit breaker trips) or motor problem (circuit breaker does not trip)
. While your thermostat may be at fault, only an HVAC technician can diagnose and remedy the issue correctly.
How do I test a blower fan relay?
Should you replace blower motor and resistor at the same time?
We do suggest that you replace the resistor at the same time
. It may not be critical, but this will keep the system more uniform. The issue may even be related to the resistor. If you know that it is not related to the issue, then you do not have to replace it.
What does a blower motor resistor look like?
How long does a car blower motor last?
Even though the manufacturer states their blower motor will last two decades, we advise all clients to expect a
10-20-year
life span due to age, use, and proactive maintenance.
What happens if blower motor relay goes bad?
If you have a faulty blower motor, you may experience
low airflow from the vents, even when the fan is on high
. There will be no air coming from the vents if your fan isn't working due to a bad blower motor resistor. Blown relay circuit fuses or melted relays are more serious signs of a bad blower motor relay.
Can you drive with a bad blower motor?
Should you drive with a bad heater blower motor?
A bad heater blower motor will not affect the safety of your car
, with the possible exception of you not being able to clear the windshield of snow, ice, or condensation if the defrosters don't work.
How do you test a blower motor?
How much should it cost to replace a blower motor?
Replacing a blower motor costs
$450 on average with a typical range of $250 to $800
. With a warranty, you might pay as little as $150 for labor alone. For high-end models, like those with large motors or access issues, you might pay as much as $2,000.
How can you tell if a blower fuse is blown?
- 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 the circuits are in good repair but the blower motor keeps blowing fuses, replace the blower motor [source: You Fix Cars].
What relay controls the blower motor?
In a blower motor, the relay supplies the power that allows the fans to circulate warmed air. Essentially an on/off switch, the blower motor relay's reactions start and end the heating process in HVAC systems by controlling the flow of current between the power source and the motor.
Where is the blower motor relay fuse located?
Why is my car blowing out cold air when the heat is on?
Low Coolant Level
The coolant (usually a mixture of water and antifreeze) in your engine doesn't just work to keep the engine from overheating: It's also the source of heat supporting the heating system. If there isn't enough coolant in your system, the heater core will blow cold air into your car.
Why is cold air blowing when the heat is on?
You Have Cold Air Blowing Out The Vents When The Heat Is On Because of
a Dirty Air Filter
.
Hiding in the filter of your heating system is dirt and debris
. If you aren't cleaning it regularly, this will accumulate over time leading to problems with your heating system's efficiency.
How do I know if my heater core is clogged?
- Fog Inside Your Car. Two things could be going on if you have fog inside your car. …
- Sweet Smells in the Car. The sweet smell in your car might not be your perfume or the donuts you're taking to work. …
- Constant Engine Coolant Loss. …
- Cold Air in the Cabin. …
- Cold Cabin/Hot Engine.
What happens when a resistor fails?
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 resistors 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.
How do I know if a resistor is burnt?
- Scarp the outer coating.
- Clean the burnt section of the resistor.
- Measure resistance from one end of the resistor to the damaged section.
- Again measure the resistance from the damaged section to the other end of the resistor.
- Add these two values of resistances.
How do you fix a blower motor resistor?
How do you test a resistor?
To test individual resistor values (outside a circuit),
connect the multimeter probe wires to the resistor's two terminals
—it doesn't matter which way round, as resistors are not directional components. Make sure the multimeter dial is in resistance measuring mode. Then check the value on the multimeter.
What are the symptoms of a bad blower motor?
- Poor or Airflow from Air Vents. This will be the first and most obvious sign your blower motor has a problem. …
- No Airflow At All From Vents. …
- Skyrocketing Energy Bills. …
- Strange Noises When You Turn on the Heat. …
- Overheating Blower / Weird Smells.
Does a blower motor resistor have a fuse?
A fuse is often located on the resistor board
. The fuse only protects the low and medium blower speeds. High speed will still work if the resistor fuse is blown.
