To understand a cabin fan that works only on its highest setting, compare it under normal, safe conditions: cold versus warm, idle versus steady speed, and light versus higher load. Record which fan speeds work and whether the controls or display also behave oddly. Change one condition at a time so the result stays useful.
Do not create a risky test just to reproduce it. Check the owner’s manual for fuse locations; do not fit a fuse with a higher rating.
Quick educational note
For information, not a diagnosis or repair instruction. Vehicle-specific checks are still required. Consult the manufacturer's guidance and a qualified technician.
How to use this information
This article explains general principles and does not establish what is wrong with your vehicle. Read the content limitations.