Radiator fans not coming on when car is started causing engine to overheat and reserve tank to burst out antifreeze. When temp sensor is unplugged only the driver side fan runs but the other doesn't move. The heat is cold when turned on but the ac is cold. Cannot tell if relay for the fans need to be replaced or the sensor or if the fans need to be replaced but the check engine light is on. We really need to know the problem so we can fix right the first time and stop guessing.
My car has 245000 miles.
My car has an automatic transmission.
The radiator fans are controlled by the Electronic Control Unit via the fan relay. The fans are supposed to come on when the engine reaches a certain temperature, or when the AC pressure comes up. If the car is overheating because the fans are not working, it will usually happen while you are moving in traffic, but cool down as soon as the car is cruising on the road. It could be that your car is low on coolant. That would explain why the heater is blowing cold. If the car is low on coolant, it may get too hot before the temp sensors even get the message. I suggest you contact YourMechanic to have a technician come out to your home or office to check out your overheating problem and recommend a solution.
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