How To Check your Furnace Blower Motor (7 Steps)
- Step 1: Turn off all power to the furnace ...
- Step 2: Remove the Furnace Access Panels ...
- Step 3: Use your voltage tester to ensure no electricity is flowing through the furnace ...
- Step 4: Feel the area near the blower motor to determine if it’s hot ...
- Step 5: Disconnect the appropriate fan wire and your common wire ...
- Step 6: Return power to the furnace ...
Full Answer
What are the signs of a bad blower motor relay?
What are the symptoms of a bad blower motor?
- 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.
How to test if HVAC blower motor is bad?
There are 5 main bad furnace blower motor symptoms to look for:
- Weak airflow coming from the vents. Weak airflow can be an indicator of other problems too such as used up air filters but problems with the motor are a likely ...
- Fully clogged vents. This too can be caused by other issues but is a common symptom for an inoperable blower motor as well.
- Weird sounds. ...
- A high energy bill. ...
- Overheating. ...
How to troubleshoot a blower motor?
Indoor Blower Motor Troubleshooting
- Faulty Wires. Make sure the power cord does not melt or the fuse blooms. ...
- Ensure the Efficiency of the Thermostat. The next step is to check the thermostat of the oven if the fan does have electricity. ...
- Weak Airflow from the Vents. ...
- Remove Any Dirt or Grim Stuck. ...
- Indoor blower motor troubleshooting
How does one test the resister on the blower motor?
To test a resistor or motor, you’ll need to know the basics of electrical circuitry and have access to a multimeter and the proper electrical specifications for the involved circuits. Testing whether there’s power flowing to the blower in the first place is a good way to rule out a bad motor.
How do you check a motor relay?
What does a blower motor relay do?
What happens when blower motor resistor goes bad?
How do I test a relay with a multimeter?
Why does my blower motor fuse blow?
How to test a relay?
How to tell if blower motor is bad?
See 2 more
How do you check a motor relay?
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).
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 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 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.
Why does my blower motor fuse blow?
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.
How to test a 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 to tell if blower motor is bad?
Weak airflow. This is one of the first signs of a bad blower motor that people tend to notice. …
Where is the blower motor relay located?
In general, the blower motor relay is in the under-hood fuse box or the under-dash fuse box. An exploded fuse can imitate the failure of relays. Many of the same signs will also occur with a faulty blower motor turn.
What Is a Blower Motor Relay?
Most of your vehicle accessories require a relay to operate – from your headlights to the cooling fan on the radiator.
What does a blown fuse mean in an air conditioner?
A blown air conditioning unit blower motor relay circuit fuse is one of the first signs of a poor or failing AC blower motor relay. It can cause the blower motor fuse to blow if the blower motor relay develops a problem. As a result, it will hinder its ability to properly restrict and distribute power.
What does it mean when a blower motor does not work?
A blower motor that does not operate at all is one of the first signs of an issue with the blower motor relay.
What is a relay in HVAC?
The relay supplies the energy in a blower engine that helps the fans to circulate warm air. The blower motor relay’s reactions in HVAC systems act by regulating the current flow between the power source and the motor.
What happens when a blower motor relay goes bad?
What happens when a blower motor relay goes bad? If the blower motor relay goes bad, the AC system cannot pump any heated or cooled air through the vent. The blower motor’s relay monitors the current used to power the blower motor and is continuously turned on and off.
Why use a relay in a blower?
To bear electrical loads that are too large for traditional switches, relays are used. In certain situations, only the high-speed circuit can be in contact with the relay. If that’s the case, the blower can run at lower speeds but won’t perform when shifted to high. This could also be true of fully automatic programs.
What is a blower motor relay?
The blower motor relay, i.e., the circuitry that provides electrical power necessary for the fan to run, essentially keeps the fan on or off. The following will happen if the relay is compromised;
Where is the blower motor located in a furnace?
Blower motors are located in the blower compartment in the furnace’s basement next to the air filter. You’ll find it supported on rails within the bottom compartment.
How Does a Furnace Blower Motor Work?
The furnace blower motor is a unique fan system that helps “pump” warm air from the furnace into your rooms/home. It comprises a fan, the fan’s housing, and wires connecting to the furnace’s main control board. The fan itself consists of a motor and shaft with metal blades.
How to tell if furnace blower is bad?
The first sign that you may have a bad furnace blower is loud and strange sounds. Typically, the fan makes a low humming sound. However, you probably have a bad fan if you start heating loud banging, whining, or grinding sounds. Other signs of a bad furnace fan include;
Why is my furnace not heating?
Poor or no airflow: If your furnace produces very little or no warm air, the fan is the most likely culprit as the appliance relies almost entirely on the fan to blow air into your home.
What is the best multimeter for HVAC?
You also have two digital options to choose from – fluke and clamp. Fluke digital multimeters are best for beginners as they’re simpler to set up and read. However, more experienced HVAC professionals prefer clamp multimeters as they can measure a broader range of electrical metrics, including resistance, voltage, watts, amperes.
What is a non contact voltage tester?
Non-contact voltage testers are inexpensive devices that you can use to quickly and reliable check that power has been shut on your appliance. Use the tester to check that the furnace is indeed off before touching any electrical parts of the furnace. Otherwise, you risk electrocution and possibly electric shock.
How to tell if a blower motor relay is bad?
How to Identify a Failing Blower Motor Relay 1 The blower motor relay does more than channel electrical current. Relays are a vital protection against electrical surges. When the relay receives a jolt of strong current or simply cannot manage and distribute its load, it will send excess current into the fuse. This forces a shutdown which protects the entire system from electrical damage. Thus, blown fuses could be a sign of relay issues. 2 Blower motor relays handle a large amount of current. Malfunctioning relays aren’t able to distribute their load properly. This can cause the relay to retain excess heat and become warm to the touch. If left unaddressed, the heat from a compromised relay can melt away the plastic casing and components around it. In extreme cases, the panel or fuse box can sustain damage as well.
Where to bring a relay to fix blower motor?
Bring your damaged relay with you to the automotive or electronics shop to ensure you’re getting the right part for your blower motor.
How Does a Blower Motor Work?
In an HVAC system, the thermostat sets the conditions for engagement. Sensors in the thermostat monitor the space’s temperature. When readings dip below the predetermined threshold, the thermostat signals the furnace to create heat.
What causes a relay to become warm?
Blower motor relays handle a large amount of current. Malfunctioning relays aren’t able to distribute their load properly. This can cause the relay to retain excess heat and become warm to the touch. If left unaddressed, the heat from a compromised relay can melt away the plastic casing and components around it.
What does a blower motor relay do?
The blower motor relay does more than channel electrical current. Relays are a vital protection against electrical surges. When the relay receives a jolt of strong current or simply cannot manage and distribute its load, it will send excess current into the fuse. This forces a shutdown which protects the entire system from electrical damage. Thus, blown fuses could be a sign of relay issues.
Why is my blower motor not responding?
When the blower motor does not respond at all, it may not be due to mechanical failure within the motor itself. Since the relay supplies the current that makes the motor move, a nonresponsive motor may be the result of a worn out relay. The blower motor relay does more than channel electrical current. Relays are a vital protection ...
What to do if replacing a switch doesn't work?
If replacing the switch doesn’t resolve the issue , replace the blower motor relay.
How do you check a motor relay?
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).
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 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 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.
Why does my blower motor fuse blow?
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.
How to test a 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 to tell if blower motor is bad?
Weak airflow. This is one of the first signs of a bad blower motor that people tend to notice. …
