What faults will occur if the car fan resistor is broken?

[AveryRose]

If the car fan resistor is broken, the following faults may occur: the air volume cannot be adjusted, there are no 1, 2, 3, or 4 speed settings, and only one air volume is available. In some cases, the fan may not work at all. Relevant information is introduced as follows: Under normal conditions, the resistance of a varistor is infinite. It is connected in parallel to the power supply and serves as overvoltage protection. When the input voltage exceeds a certain value, its resistance suddenly decreases, causing the circuit to short-circuit and forcibly blowing the fuse to protect the electrical appliance. Generally, the inverter's fast silicon is prone to damage. If the rectifier silicon is damaged, there may be a sudden overvoltage or overcurrent. Trigger disturbances caused by load disturbances and power fluctuations can also damage the rectifier silicon. Specific issues need to be analyzed based on the damage conditions.

[VanWeston]

A faulty blower motor resistor can be quite troublesome. I've helped friends deal with this issue several times. When the resistor fails, the fan speed gets stuck - usually only working at high speed without the ability to switch to low or medium settings. The AC suffers too, providing poor cooling in summer when the fan just hums loudly without delivering cool air, which is really uncomfortable. What's worse, the engine may overheat, especially in traffic jams where temperatures spike quickly, forcing you to pull over for inspection. The root cause lies in the resistor's role of regulating current - when broken, current flows straight through without regulation, leaving the fan without speed control. Don't underestimate this issue; I recommend getting it checked at a professional shop for both the resistor and wiring. Delaying repairs may damage the fan motor too. For DIY attempts, first try replacing the fuse, then test the resistor's value if that doesn't work, but always prioritize safety and avoid random wiring. Timely repairs save much hassle, preventing potential engine overheating and costly component replacements.

[DelDylan]

I deeply relate to this issue, having driven for over a decade and frequently encountered blower motor resistor failures. When it fails, the fan may get stuck in high-speed mode or stop working entirely, causing the AC to malfunction. I remember one long trip where the fan only blew at high speed—the cabin temperature rose instead of cooling down, and the hood became scalding hot, which was extremely dangerous. The resistor acts like a switch manager; when current control is lost, the fan goes haywire. For inspection, basic tools like a multimeter can test for continuity—a simple DIY that saves time. Repair costs aren't high either; a new part runs about 200-300 RMB, and a professional can replace it in half an hour. I urge everyone not to overlook this, especially in older cars prone to such issues. Regular maintenance checks on the fan system can prevent bigger problems. Safe driving is paramount—address resistor faults early to avoid engine overheating and costly repairs later.

[StGriffin]

I observed that a faulty fan resistor is a major hidden hazard. When the resistor fails, the fan speed control malfunctions, potentially causing the fan to only operate at high speed or fail at low speed. Air conditioning efficiency drops sharply, making the air vents uncomfortably warm. The risk of engine overheating increases, especially in congested city traffic. Prioritize safety by repairing it early—don't hesitate to take your car to a shop for inspection.