How do you test a bad blower motor relay?

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 know if my blower motor relay is bad?

Symptoms of a bad heater blower motor resistor

  1. Fan does not work at all, so no air comes out of the vents.
  2. Fan only works on some speeds and not others.
  3. Fan only works on the highest speed.
  4. Fan runs all the time and can’t be controlled with the fan switch.
  5. You see smoke coming out of the vents.

What does a blower motor relay do?

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.

What happens if your blower motor relay is 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.

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What happens when blower motor 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.

How do you check a motor relay?

The only tool required to check a relay is a multimeter. With the relay removed from the fuse box, the multimeter set to measure DC voltage and the switch in the cab activated, first check to see if there are 12 volts at the 85 position in the fuse box where the relay plugs in (or wherever the relay is located).

Is there a fuse for the blower motor?

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.

How much is a blower motor relay?

Blower Motor Relay Replacement Cost – RepairPal Estimate. Labor costs are estimated between $37 and $46 while parts are priced at $37. This range does not include taxes and fees, and does not factor in your specific vehicle or unique location. Related repairs may also be needed.

What are the symptoms of a bad blower motor?

Here are just a few of the signs that your blower motor is going bad.

  • Weak airflow. This is one of the first signs of a bad blower motor that people tend to notice. …
  • Noises. Have you noticed any unusual noises coming from your vehicle’s HVAC system? …
  • Smoke or smells.
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How do I test a relay with a multimeter?

Grab a multimeter and set it to Ohms. Touch the leads across the electromagnet coil pins and measure resistance. Anywhere from 50-120 ohms is OK. Out of range or open means a bad electromagnet coil winding and time for a new relay.