How to Determine if a Car Fan is Functioning Normally?
3 Answers
Determine whether the car fan is functioning normally based on the following conditions: Judgment based on water temperature: When the water temperature reaches 100 degrees, such as when the air conditioning is turned on, the fan operates at low speed. When the water temperature reaches 112 degrees, the fan will operate at high speed. Judgment based on air conditioning pressure: Connect the high and low pressure gauge hoses to the system's high and low pressure service (charging) ports respectively. Set the air conditioning system to the coldest setting, the blower speed to the highest, and the air circulation to internal with the air outlet directed towards the face. Open all car doors. Then, run the air conditioning system (the engine should maintain a certain speed, typically 1500r/min; using only idle speed may affect the accuracy of fault diagnosis). Observe the pressure gauge group (for R12 or R-134a, the normal working pressure is: low pressure side at 1.8～2.1kgf/cm2, high pressure side at 12～14kgf/cm2 and 13～15kgf/cm2 respectively). If the readings are not within this range, the air conditioning system has a fault.
To determine if the car fan is functioning properly, pay close attention during regular driving. Start the engine and let the car run for about ten minutes, such as idling in place or taking a short drive, to warm up the engine. Then, open the hood to check if the fan is running—normally, the fan should rotate smoothly, with its speed increasing or decreasing based on temperature changes, but overall operation should be fluid. The fan becomes more active when the air conditioning is on, which is a normal cooling response. If the fan operates without unusual noises, the blades remain stable without wobbling, and the temperature gauge needle stays steadily in the middle range, then it’s generally fine. It’s advisable to develop a habit of performing this simple check monthly, especially during summer when temperatures are high and the fan is under greater load. Cleaning dust around the fan can prevent overheating issues. If the fan malfunctions, it may cause the water temperature to spike, potentially damaging the engine—safety is the top priority.
I used to work in car repair for a while, and here are a few tips to check if the fan is functioning properly. Your ears are key: the fan should produce a consistent sound when operating, without any abnormal noises like clicking or screeching, which could indicate bearing wear or blade damage. Touch is also important – when the fan spins, the airflow should feel strong with moderate heat. If the fan doesn’t turn on at idle or during high temperatures, or if its speed fluctuates, you should suspect issues with the temperature sensor, relay, or wiring. The coolant temperature gauge should stay stable around 90 degrees, and don’t overlook checking the fuse. During regular maintenance, gently clean the blades – excessive dust buildup can affect balance and increase noise. These small details can help detect problems early.
