Problems with a blower motor resistor are common in many cars. 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.
How do you tell if it’s the blower motor or resistor is bad?
Bad Blower Motor Resistor Symptoms
- Only One Speed From Blower Motor. One of the most common symptoms of trouble with the blower motor resistor is when the fan gets stuck in one setting. …
- Various Airflow Settings Not Working. …
- No Air Coming From Vents.
What are the symptoms of a bad blower motor?
What Are Signs Your Blower Motor Needs to Be Replaced?
- 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.
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.
Should I replace blower motor and resistor?
There is still a chance that the blower motor control could be faulty, but if the control knob feels good and all the fuses and relays are good, chances are you need to replace the blower motor resistor.
Can a bad blower motor resistor cause no AC?
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 I need a new blower motor?
Be aware of the following signs and symptoms of a bad AC fan motor.
- AC Fan Doesn’t Start. Even though you have the AC turned on, the fan does not start.
- AC Fan Doesn’t Stop. …
- Slow Rotating Blades. …
- Outside Fan Blades Are Still. …
- Rattling, Humming, and Buzzing Noises. …
- AC Runs Intermittently. …
- No Cold Airflow.
What happens when 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.
What would causes a blower motor resistor to go bad?
In most cases, a blower motor resistor fails due to corrosion or overheating. Sometimes, the mechanical resistance to the motor rotation causes an excessive electric current that can overheat and prematurely damage the blower motor resistor.
Why does my blower motor resistor keep burning 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.
Why does my blower motor only work when I hit it?
Blower motor only start working after i hit a bump.
In most cases that is a sign of worn down blower motor brushes not making a good contact. In some cases the blower motor/resistor pigtail could cause erratic operation of the blower motor too.