Why Doesn't the Fan Turn On After Replacing the Coolant?

[LeMalia]

After replacing the coolant, the fan does not turn on because the vehicle's fan control sensor is set on the radiator. The fan will only operate once there is no air left in the pipes after replacing the coolant. Coolant is a type of liquid containing special additives, primarily used in liquid-cooled engine cooling systems. It has excellent properties such as preventing freezing in winter, boiling in summer, and protecting against scale and corrosion throughout the year. How to determine if the coolant is low: Observe the coolant warning light on the dashboard. If it lights up, it is likely due to low coolant levels, though it could also be caused by excessively high temperatures inside the cylinder. Check the coolant reservoir. If the liquid level is below the minimum mark (MIN), do not continue driving and add coolant promptly. Check the water level markings on the coolant bottle. The coolant level should normally be between the maximum and minimum marks. To determine if the coolant is low, check the markings. If the coolant is below the minimum mark, it indicates a low coolant level.

[StBrianna]

Last time after changing the coolant, I also encountered the issue of the fan not spinning, which was quite concerning. Later, I discovered that I forgot to tighten the air bleed screw when adding coolant, causing air to accumulate in the pipes and leading to inaccurate temperature sensor readings. Another possibility was accidentally loosening the fan's power connector while removing the radiator—these connectors may look sturdy but are actually quite delicate. Additionally, overfilling the coolant caused it to overflow and short-circuit the electric fan motor. Finally, I remembered to check the fuse box, and sure enough, a 20A fuse had blown. My suggestion is to first check all the connectors, then test the temperature sensor. If you don't have the tools, it's best to return to the repair shop for a recheck.

[DelSilas]

My old Bora recently had its cooling fan stop working right after a coolant change, and it took a while to figure out why. The repair shop apprentice didn't properly bleed air from the system when replacing the coolant, causing the radiator temperature to read falsely low and preventing the fan from activating. Also, the wrench accidentally knocked loose the fan relay during the operation - that component is tucked away in a corner of the fuse box and is particularly easy to overlook. If the new coolant concentration is too high, it might also affect sensor sensitivity, so it's best to check the mixture ratio with a refractometer. Additionally, coolant leaks in the system could splash onto circuit boards and trigger short-circuit protection. I recommend re-bleeding the air, checking fuses and relays, and taking a look under the chassis for any signs of fluid leaks while you're at it.

[AvaLynn]

Have you noticed? Many car owners experience their fans not spinning after replacing the coolant, and the issue often lies in the operational details. I've handled several cases where it was related to air—the cooling system wasn't fully bled, causing the temperature sensor to misjudge the water temperature as not high enough to activate the fan. Another possibility is coolant seeping into the fan connector, leading to poor contact; it's best to unplug the connector and dry any moisture. Also, check the cooling system fuse in the main fuse box under the hood—sometimes, removing the radiator can accidentally short-circuit the wiring. Additionally, pay attention to the fill level; exceeding the upper limit can cause pressure to push the seals open, leading to leaks. A simple solution is to re-bleed the system and top up the coolant—these tasks can easily be done by yourself.