Why does the car overheat at idle but run normally when driving?
4 Answers
Here are the solutions for the issue of the car overheating at idle but running normally when driving: 1. Visit a professional repair shop or 4S store: Clean the condenser, radiator, check the fan, and cooling system. 2. Proper flushing: When washing the car yourself, you can use a hose to flush appropriately, especially through the gaps around the car emblem where the condenser is located. Over time, it can accumulate dirt, dust, leaves, and other debris. 3. Turn on the internal circulation when using the air conditioning: This helps save costs, maintain a lower temperature inside the car, and avoid waste. 4. Use intermittent cooling: After the interior temperature has decreased, you can turn off the air conditioning and turn it back on after a while.
My car had this issue last year—the temperature gauge would shoot up when stopping at red lights, but return to normal once driving again. At first, I thought it was low coolant, but the inspection revealed a stuck cooling fan. At idle, the fan either wouldn’t spin or rotated too slowly, preventing the radiator from cooling, which caused the engine temperature to rise. Once moving, the incoming airflow helped dissipate heat, bringing the temperature back down. Older cars are prone to such problems, like aging fan motors or short circuits in the control wiring. I later had the fan motor replaced at the repair shop, and the issue was resolved. I recommend checking your coolant level—make sure it’s not too low—and verifying the thermostat’s functionality. Addressing it early saves hassle and avoids costly engine overhauls. Safety comes first when driving—fix abnormal temperature issues promptly.
After driving for so many years, I've encountered several instances where the engine overheats at idle but runs normally while driving. This is mostly related to the cooling system. At idle, the fan either doesn't start or malfunctions, and natural airflow isn't sufficient for cooling, whereas the airflow from driving speed provides effective cooling. I recommend focusing on checking if the fan is operating properly. Sometimes it's due to a faulty relay or a stuck thermostat, and an underperforming water pump can also cause insufficient coolant circulation. If the coolant is degraded or insufficient, idle conditions are more likely to expose the problem. Don't delay—get it checked at a professional shop as soon as you notice the issue. Replacing a part doesn't cost much, but avoiding engine overheating and cylinder scoring is crucial. During regular maintenance, pay attention to cleaning the radiator fins and checking the fan function to effectively prevent such minor issues.
The car's temperature rises when stationary but returns to normal when driving? In most cases, it's due to a faulty cooling fan. At idle, the engine's cooling fan doesn't spin, leading to poor heat dissipation and rising coolant temperature. When driving, the increased airflow provides automatic cooling, resulting in noticeable temperature drops. Check the fan blades, electrical connections, or the temperature control switch. Low coolant levels or blockages are also common causes. Get it repaired as soon as possible to avoid engine damage and being stranded on the road. Just keep an eye on temperature changes during normal driving.
