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Q: Constant overheating and hot AC not working.

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Part of the problem is that radiator fans are not turning on, but that they do work when the AC cycles. I have replaced the radiator, the thermostat, the water pumps, the radiator cooling fan switch, timing belt, and run head gasket sealant through the radiator. The car overheats quickly when stopping. However the car still drives smoothly and handles well. When the problem first started I drove it until there was white smoke billowing into the cab. I live in Ventura county, California.

My car has 186000 miles.
My car has an automatic transmission.

A: Hi there. If the fans aren’t coming on with...

Hi there. If the fans aren’t coming on without the AC on, then there is a fault within the cooling fan circuit. Along with the radiator fan switch, there are three more coolant temperature sensors; one for the ECU, one for the gauge, and one for the radiator fan control for low speed fan. It sounds like there could be a fault with the one for the fan control. Locate the coolant temperature sensor for the fan control near the thermostat area on this vehicle; it should have a green connector with 2 wires. The sensor can be tested with a digital volt/ohm meter and the readings compared against specifications. I suggest having a qualified technician perform an inspection to avoid replacing unnecessary or incorrect parts. Your Mechanic has several available technicians that can assist you with a car is overheating inspection.

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