My car was jumped incorrectly. The car seems to operate just fine, but the fan does not blow. When the ac or heat is turned on (to any level), nothing seems to be blowing out of the vents. The fuses were checked visually and several replaced. One of the fusible links was removed and replaced (one of the “links” was blown). Although the blower fan is not receiving power, it is operational. I am not sure what to check or do next? I would thinking about checking the fuses with multimeter (in case one was missed). Any help would be appreciated.
How can the blower fan be operational if it’s not receiving power?
The blower fan was bench tested and tested with a multimeter, but is not operational in the car.
The blower motor is powered by cartridge fuse # 4, 50 amp, “HTR” in the engine compartment fuse box.
Most fans have an inline fuse. Did you check that?
I visually inspected all the fuses in the engine and driver compartment, but will check that specific fuse tomorrow with a multimeter. Thanks for your response.
Thanks for your response, do you have any idea where this inline fuse would be located?
Just for yucks and giggles, turn the ignition on, set the blower speed to high, and reach under the passenger of the dash with the handle of a screwdriver and rap on the blower motor.
If the blower works, replace the blower motor.
Tester
No, not on your car. Measuring for continuity from the fuse box to the fan connector might give you a clue.
There is also a resistor in-line under the glove box. It controls the speed of the fan. Possibly this thing is dead. Normally one would expect to get a default high-speed with a dead resistor, but your model car might be different.
There is only one fuse for the blower motor, it is in the under hood fuse box. Japanese imports from the 1980’s had fuses in odd places within the wiring harness.
The A/C amplifier supplies the ground for the blower motor. Lexus vehicles have automatic temperature control, they do not have manually operated fan switches with blower resistors.
Did you verify this with a volt meter or test light?
Manual or automatic, doesn’t matter, it still requires a resistor to change the speed of the blower by reducing or raising the voltage.
In recent decades the blower motor has been controlled by a duty cycled transistor, something like the device in your post. Resistor blocks only provide 4 or 5 speeds, a blower module can provide multiple fan speeds. Chrysler used blower modules before the first Lexus was manufactured. You won’t find a resistor block on this vehicle.
No luck when rapping on the blower motor. Would have been nice it if was just the blower motor shorting…
Yes, Nevada_545 that is my understanding as well. My make and model does not have a separate blower motor resistor.
Also, to verify the blower fan was not receiving power I unplugged and removed the blower fan from under the dash and stuck the multimeter leads in the terminals while the car was running and the fan was turned on. I received a voltage output of 0, but the leads didn’t fit well, so if you have a better way to test I am all ears.
It is best to back prove the connector while it is connected to the blower motor, inserting a probe into the connector can cause damage.
Connect the negative meter lead to body ground, test the connector for power with the positive lead. The white wire is battery power, the blue wire is the controlled ground.
Thanks for the back probing information, that is much better and easier. (I practiced on the light that sits in the plastic cover protecting the blower motor to make sure I was doing it correctly, and then moved onto the the blower motor.) According to my voltage measurements, the motor is not receiving any power.
Also to answer your earlier question, I have checked the “HTR” fuse (50A) in the fusible link as well as the “HTR 2” fuse (7.5A) and both are good.
Could it be a relay? I am looking at the chilton wiring diagrams to see what is in between the fuses and the motor, but it is pretty hard to dissect.
There is no relay, the power is direct. AF4 in the diagram in a connector behind the left kick panel. Is there power at the 50 amp fuse?
I can’t thank you enough for your time and help! Sorry I don’t know a lot, but could you help explain how I can test to see if there is power at the fuse? It’s part of this fusible link. I replaced this link a few days ago in hopes of fixing the issue, but no luck! The part was ordered from the lexus dealership.
