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I drive a 2013 Hyundai Tucson L.

For a while now, the dial controlling the fan speed has been acting up. Often it only works on a single, or two, settings. There are five settings (0, 1, 2, 3, 4). Sometimes the setting it works on changes randomly. Once or twice the knob was stiff and wouldn't turn easily.

On the Google machine I found out there is a blower motor, and a blower motor resistor -- both exposed directly under the glove box. The guy in this video shows how to change them out: https://www.youtube.com/watch?v=b90Io3_MNio

I decided to unhook the power connectors on these first, and clean them using a spray called Revive, advertised for just such jobs. I sprayed the plug and outlet for both the motor and resistor, and plugged them back in after the spray dried nicely. No luck.

Next I decided to hook up my multimeter to the power leading to each of these, and turn the knob to see the impact. At dial 0, 1, 2, 3, 4 the incoming motor power read 4 V, 12 V, 12 V, 4 V, 4 V, respectively. No amperage was detected (odd?).

At dial 0, 1, 2, 3, 4 the incoming power to the resistor read 9 V, 9 V, 0 V (eek!), 9 V, 9 V, respectively. Amperage was 8.9 mA, 63.3 mA, 0 mA, 8.1 mA, 8.1 mA, respectively.

Am I right to conclude I should not buy any resistor or blower motor since the zero volts incoming is weird? This means the problem is in the knob itself, right? Or at least upstream? I saw some videos online how to take apart the radio/climate control panel, should I do that and clean the knob connectors? And if that doesn't work, should I buy a new climate control panel and put that in there? What would you do? Thanks so much!

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  • Welcome to Motor Vehicle Maintenance & Repair!
    – Pᴀᴜʟsᴛᴇʀ2 ♦
    Commented Sep 29, 2021 at 0:06
  • I'd try and eliminate your resistor first. You may not need a new one, you can sometimes revive them by taking them out and soaking it overnight in white vinegar. It's worked for me in the past.
    – GdD
    Commented Sep 29, 2021 at 8:21

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It does sound like it is the switch behind the control knob that is at fault. The fact that it is sometimes stiff would indicate a mechanical fault with the switch.

Are there electrical connections to a switch directly behind the control knob, or is there a mechanical mechanism that moves an electrical switch that is located somewhere else?

If the electrical switch is directly behind the knob, it should be a fairly easy job to diagnose and replace the electrical switch.

If the electrical switch is located elsewhere, you need to check the mechanical connection too, but it is still probably going to be a faulty electrical switch since you say it can change state randomly.

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  • Not too sure what is behind there, need to re-watch some YouTube videos, but I will try taking it apart and cleaning it, and if no go, replacing that part.
    – Eric
    Commented Sep 29, 2021 at 19:18
  • I ended up removing the climate control panel and the block connector plugging into it (just behind the fan dial) had evidence of melted plastic and burn marks. I had to swap out the climate control panel from one I bought on eBay (new ones were too expensive). It now works fine. I had previously ruled out the fan motor and resistor by attaching a multi-meter to these (found under the glove box) and it seemed they were not being fed proper/consistent amperage by the climate control panel.
    – Eric
    Commented Nov 8, 2021 at 17:48

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