How To Test A Blower Motor Resistor With A Multimeter

November 16, 2024 Post a Comment

How to test a blower motor resistor with a multimeter

Turn off your vehicle, set your multimeter to Ohms, and check for resistance between the blower's positive and negative terminals. You may also turn the car key to run without starting the engine, put the cooling system at full blast, and check for DC voltage. If none of these produces a reading, the blower is bad.

How do I know if my blower motor resistor is out?

Here are some common signs that your vehicle's blower motor resistor is bad:

Loss of HVAC fan control (total or certain speeds)
The fan only works on its highest speed setting.
No air coming from vents.
Intermittent or inconsistent fan speed.

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.

Can a blower motor resistor be bypassed?

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.

How can you tell if a resistor is bad?

If the resistor is fine, the multimeter will show its value in Ω, kΩ, or MΩ. However, if the resistor is bad or damaged, the multimeter may display 0 or 1. If the value 0 is displayed, the resistor is damaged, and the current can't pass through.

Is there a fuse for blower resistor?

A fuse is often located on the resistor board. The fuse only protects the low and medium blower speeds. High speed will still work if the resistor fuse is blown.

What causes a blower motor resistor to go out?

In most cases, the blower fan resistor is failing either due to overheating or corrosion. If the blower fan fails, your car will not blow any forced air. However, sometimes the problem can be with the blower motor itself. This is especially apparent when you have replaced the blower fan multiple times.

Can you repair blower motor resistor?

The average cost to replace the blower motor resistor at a repair shop is between $44 and $55 in parts and $70 in labor costs, for a total cost of around $114 to $125. What is this? On the other hand, you can easily fix the blower motor resistor at home in about an hour (even if you're a beginner) and for around $70.

How do I know if my blower fan relay is bad?

One of the first symptoms of a problem with the blower motor relay is a blower motor that does not function. As the relay is the switch that supplies current to the blower motor, if it fails internally, then power may be cut off from the blower motor circuit causing the motor to no longer function.

What happens when a 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.

Can a bad blower motor resistor cause no AC?

If the airflow from the vents is weak… A damaged blower motor resistor will work on one fan speed which may not be enough to keep the inside of your car cool or warm enough.

Should you replace blower motor and resistor at the same time?

We do suggest that you replace the resistor at the same time. It may not be critical, but this will keep the system more uniform. The issue may even be related to the resistor. If you know that it is not related to the issue, then you do not have to replace it.

What does the blower motor resistor connect to?

The traditional blower motor resistor is connected to ground and wired in series with the blower motor assembly. Blower motor resistors have several resistors with different resistances. This controls the current that runs through the blower motor.

How do you test a 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.

Is a blower motor and a blower motor resistor the same thing?

The blower motor switch is the actual switch or button on the dash that you use to increase or decrease the fan speed. The blower motor IS the fan. The blower motor resistor is what allows the fan to work at different speeds as opposed to just off and on.

Can you test resistors with a multimeter?

Pick out a random resistor and set the multimeter to the 20kΩ setting. Then hold the probes against the resistor legs with the same amount of pressure you when pressing a key on a keyboard. The meter will read one of three things, 0.00, 1, or the actual resistor value.

What is the most common resistor trouble?

The most common problems to occur with fixed resistors are a change in resistance or a complete failure. A complete failure occurs when the resistor overheats and burns out. When the resistor interior is burned out, it produces an open circuit.

What is the best way to test a resistor?

Testing a Resistor with an ohmmeter is the best, easiest and most effective way to tell whether a resistor is good or not. To set up for the check, we take the ohmmeter and place its probes across the leads of the resistor. The orientation doesn't matter, because resistance isn't polarized.

How long should a blower motor resistor last?

The blower motor resistor is designed to last for the car's lifespan. In most cases, these resistors will wear out long before the car does. Usually, the wear that the blower motor resistor has is due to the constant use that it gets and the heat that it is exposed on a regular basis.

Is there a relay for the blower motor?

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.