How do you test a blower motor resistor?

Can you bypass blower motor resistor?

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. 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.

How do you test a blower motor with a multimeter?

Using a multimeter set on the Ohm scale, use the positive lead and test the black wire. To check the purple wire for current, use your ignition key and turn it to the run setting, turn the heater power to full power and set the multimeter to DC power. If your meter reads “no current” the motor is no good.

What happens when blower resistor goes bad?

If the resistor shorts or fails, it may cause the blower motor to remain stuck on one fan speed. The heating and air conditioning systems may still function at one speed, however the resistor will have to be replaced in order for full functionality to be restored.

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What happens when blower motor relay goes bad?

If the blower motor relay develops any sort of problem that hinders its ability to properly limit and distribute power, it may cause the blower motor fuse to blow. Any sort of electrical spikes or excessive current from a bad relay will blow the fuse and cut power in order to protect the system.

Can you bypass a resistor?

you don’t have to remove the existing resistor wire to bypass it. You leave it in place and : a) attach a 14 or 16 gauge jumper wire with scotch-locks at either end of the pink ni-chrome wire under the dash.

What is the purpose of a blower 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.

What does a final stage resistor do?

The final stage (or blower motor) resistor controls the speed of the blower motor in your heating & air conditioning system. Faulty resistors can cause a list of erratic issues, from the fan running when the car is off, to only having one fan speed available.

How much does it cost to fix a blower motor resistor?

The average cost for a Blower Motor Resistor Replacement is between $108 and $137 but can vary from car to car.

Why is my blower motor not working?

In a situation where the motor doesn’t work on any speed, the most likely causes are: a blown power supply fuse, a bad motor ground connection, bad motor speed control module or a failed motor. On all systems, a failed blower motor is least likely. Start by checking the blower fuse and HVAC controller fuse.

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What are the symptoms of a bad blower motor?

7 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.

How do you test a blower motor relay with a multimeter?

Connect a test light or multimeter to the ground (black lead). Turn the ignition key to the on position (engine off), and remove the relay. Using the probe, test all terminal sockets in the relay connector. Two of the four should have power.

How do I check fuses with a multimeter?

Test the fuse.

If you’re using a digital multimeter set to measure resistance, touch the probes together to get an initial reading. Then put the probes on either side of the fuse and check if the reading is similar. If it is, then the fuse works properly. If you get no reading or “OL”, then the fuse has blown.