Trying to diagnose blower fan not working.

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Feb 6, 2021
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Massachusetts
Vehicle in question is a 2016 Hyundai Accent with manual temperature controls. Blower was replaced awhile ago and checks out fine, the fan will randomly start and stop working while driving. Tried a new blower resistor, did nothing. Swapped the fan fuse, nothing.

Voltage at the fan connector is 0, and voltage at the connector for the resistor is 0, I'm starting to suspect the actual fan controls, odd thing is when the fan stops functioning, the AC will run even if the knob is turned to zero, which doesn't happen obviously when the fan is functioning, the blend door controls all work when the fan stops as well, as I can hear the doors moving.

Any suggestions before I replace the control assembly? Don't want to do that and still have a problem as the job is a huge pain.
 
I am no expert on Hyundai but it sounds to me like the fan switch itself is bad, especially with the AC running when the switch is off. Maybe if you could find a wire diagram for it to jump some of the fan speed wires you could tell for sure, or just try a new switch, even though the job is a pain. With everything else you have checked, the switch sounds like the next logical cause.
 
just hook up a voltmeter to fan (+) input wire & black to ground. Cycle through the speed settings.
High is usually full battery/system voltage, all the lesser settings taper the volts DC. The contacts in the on/off multi- speed switch
tend to take a beating, plus the heat can cause them to melt too. Have no idea if the fan speed switch is separate unit, like in older cars. It tends to be a separate unit due to the frequent re-settings it receives.
If the resistor pack alone is bad, the high speed setting usually remains functional.
 
Check the connector at the fan control switch.

What sometimes happens, at least on Kia’s, is when the blower motor goes bad, it draws too much voltage and burns/melts the connector. If you see something like this picture, you’ll need to splice in a new connector, a new blower motor and possibly new control switch

8EBD0C50-BE5F-482F-8447-D4EEE46DF9A3.jpeg
 
If there is any digital display you can usually get some sort of code out of Climate Control systems, usually a specific flashing sequence.
 
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