This is normal. The fan is controlled by a thermostat, and continues to turn until the radiator has cooled.
Radiator fan running high may not only be because of a bad thermostat. It may be the hoses, the radiator, heater core, water pump, thermostat housing, head gasket, freeze plugs, automatic transmission oil cooler, or cylinder head(s).
In many modern cars, the engine control unit (ECU) monitors the temperature, and if it detects that the engine is still too hot after shutting down, the fan will stay on until the temperature lowers to a safe level. This is particularly common after driving in hot weather or if you've been sitting in heavy traffic.
If your fan limit switch is set to AUTO but the fan continues to run without ever stopping, you'll need to call a professional. Two problems that could cause your fan to run without stopping include: A bad fan limit switch that needs to be replaced. Bad thermostat wiring.
Faulty Thermostat: If both the fan and either the cooling or heating system are running unexpectedly, you may have a faulty thermostat (2). A malfunctioning thermostat may not properly send the on/off commands to the fan, causing it to run continuously. In this case, it may be necessary to replace the thermostat.
If the control board is faulty or malfunctions, it may not send the signal to the fan to tell it to shut off. The same can also happen if the wiring between the control board and the fan is damaged or there is a loose electrical connection.
Keeping your thermostat fan set to "ON" may seem like a great way to circulate air throughout your home or office, but it actually has some disadvantages. Using this setting does lead to more energy consumption, as the blower's motor runs more frequently - you may notice slightly higher energy bills.
This isn't necessarily bad for your fan, but it is usually a sign of a bigger problem. Common causes for fans not turning off when they should include faulty thermostats, bad wiring, and stuck relays. These problems are not easy DIY repairs and should be left to an HVAC professional.
Leaving the fan running reduces wear and tear on the motor since it's not starting and stopping repeatedly. It's also beneficial to boost filtration, but leaving it on this setting has more drawbacks than benefits. When it runs nonstop, the fan consumes more energy, and the air filter needs frequent replacement.
A bad thermostat can be detected when your AC or furnace is not turning on, your HVAC systems are not turning off, the thermostat not responding, your HVAC system is short-cycling, the room temperature not matching the temperature displayed on the thermostat, and the programmed setting resetting themselves.
The Fan Limit Switch is in Manual Override Mode
This will ensure that your furnace fan runs only when necessary and not continuously. The fan limit switch is typically located near the blower motor or in the control box. It just requires a press from your finger to behave accordingly.
Scan your computer for malware
Malware (virus, spyware, trojans, and so on) can cause a computer fan to run constantly due to an overload on the processor (CPU), this in turn causes the fans to run constantly and fast. Spyware and other types of malware are a big cause of many computer problems.
The purpose of designing this part is only to turn it on and off when necessary and if the radiator fan runs continuously, this will shorten the lifetime of this component, and more seriously, it can make drain off your battery causing your car not to start.
In a car, the cooling fan relay takes a signal from the car's computer and turns on or off the cooling fan. After many cycles of switching on and off, the relay will eventually fail, and when it fails, it could either be “stuck” at the closed or open position, leaving the fan permanently on or off.
When the temperature in the room rises above the set temperature, the thermostat sends a signal to the fan to turn on. The fan then circulates the air in the room, creating a cooling effect. As the temperature in the room decreases, the thermostat sends a signal to turn the fan off.
There are two settings on your thermostat to control the fan – auto or on. AUTO means that the fan turns on automatically only when your system is heating or cooling air. Once the thermostat reaches the desired temperature, the entire system shuts off until the next cycle.
If you wonder, “How long should my HVAC fan run per hour?” then the answer is between ten to 20 minutes for two or three cycles. This works best when your home has a mild outdoor temperature. When temperatures shift strongly towards 0 or 90 degrees (heating or cooling), you will need to run the fan longer.
Incorrect settings on your thermostat or fan limit switch can cause the fan to run continuously. Faulty wiring or a broken fan limit switch can also cause your fan to keep running. You can diagnose and fix some furnace fan issues on your own. Faulty wiring or a broken switch will require professional repair.
– Fans don't need to be left on at all times, so if you have a fan in your room that you don't plan on using all day, leave it off. Fans that are left on constantly can use more electricity than they should, and their blades will become dull quickly, even without being used.
Why Is My AC Fan Not Spinning? In short, common issues that can cause an air conditioning unit fan to stop spinning are electrical issues, problems with the capacitor, contactor issues, a burnt out air conditioner motor, a broken fan belt, or clogged air filter.
If your furnace fan runs all the time, even when your thermostat is not calling for heat, check the fan switch on your thermostat, if it has one. It should be set to the “AUTO” position. If that's not the problem then you might have a bad temperature sensor in the furnace.
Your thermostat fan setting controls your HVAC system's blower. The blower helps circulate cold or hot air throughout your home until the temperature reaches the thermostat setting. ON means that the fan is constantly blowing, even when the desired temperature has been reached.
You can expect a more considerable maintenance burden if you run the fan continuously, even if you're running the AC fan without cooling. The filter will clog sooner, and the mechanical parts need more frequent attention to avoid breakdowns.