Hey Sam,
Typically if an RV vent fan is having issues it's going to be caused by your power and ground or a faulty circuit board. With yours running full blast randomly and the buttons not working the power most likely isn't the issue but it wouldn't hurt to check the voltage running to the power wire with a multimeter # PT89ZR to see if you're at 12 volts or if you're getting less or more, causing an issue for the circuit board. You should also verify that you have a good ground connection.... view full answer...
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