Why does my car only blow air on high?

Why does my car only blow air on high?

If your heater only blows when the setting is on high, this may suggest that you have a faulty blower motor resistor. The highest speed setting may still work because in most cars in the highest fan speed settings the current bypasses the blower motor resistor. On all systems, a failed blower motor is least likely.

Why does my fan only work on high?

Resistor module replacement 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. Remove the screws, and swap out the resistor module.

What are the signs of a bad blower motor resistor?

What are the symptoms of a bad blower motor resistor?

  • No Air.
  • High speeds only.
  • Low speed only.
  • Fan won’t turn off.
  • Blower motor works on some settings but not others.
  • Smoking vents.
  • Burning smell.

Can a blower motor resistor be intermittent?

The blower motor resistor is receiving power but not the full force. Reduced air movement can occur at all of the different speed settings of the motor blower. Depending on how much resistor is still functioning, the reduced airflow could be an intermittent problem.

Is there a way to test a blower motor resistor?

If you want to do a quick test of the blower resistor, you can check the resistance of each of the resistors with a multimeter as follows: set the tool to read ohms (a measurement of resistance) and connect one of its probes to the common output terminal of the resistor.

Where does the blower motor resistor go?

On many vehicles, the blower motor resistor, which comes as a module that connects to an electrical wire and is mounted near the blower motor, is accessible by removing the glove box or checking under the dashboard. On others it’s behind the dashboard, and part of the dashboard may have to be disassembled to reach it.

How does a cooling fan resistor work?

The resistor is powered by the ignition and enables the cooling fan to run at slow speed. Once the engine reaches a manufacturer-predetermined temperature, a temperature switch indicates to the cooling fan resistor that the fan should run at high speed to draw more air through the radiator and provide extra cooling.

How do I know if my cooling fan resistor is bad?

Usually a bad cooling fan resistor will produce a few symptoms that can alert the driver of a potential problem that should be serviced.

  1. Engine overheats. One of the first symptoms of a potential problem with the cooling fan resistor is engine overheating.
  2. Cooling fan speed issues.
  3. Cooling fans never turn off.

How do you test a fan control relay?

How to Check a Fan Relay

  1. Look at the markings on top or side of the relay case and locate the two control circuit terminals, which connect to the relay’s coil, and the two power circuit terminals, which let electrical current pass to the fan.
  2. Connect the leads of an ohmmeter to the power terminals on the relay.

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