Engine Overheating

STAR 2000

MEMBER
2004 MAZDA 3
2.3L
4 CYL
2WD
AUTOMATIC
193,000 MILES

When the fan runs, I unplugged the connection to the temperature switch on the engine, the fan ran continuously. When I plugged the connection back, the fan stops immediately. And it can only be run by switching on the air conditioner. What might be the root cause? I suspect short circuiting on the line. The temperature rise when the car stops. Please help me.

5 Replies

SATURNTECH9

MECHANIC
30,869 POSTS

A lot of cars run the fan continuous when you unplug the coolant temperature sensor because it has no coolant temperature input. This is to help protect the engine this would just be a guess because nothing was tested yet but sounds like a bad coolant temperature sensor. The they fail they usually read lower then actual coolant temperature.

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Wednesday, August 3rd, 2016 AT 7:25 AM

STAR 2000

MEMBER
3 POSTS

Ok I will try and replace the temp sensor and repeat what I did with the first one, anyway thanksTech9 I will keep you updated if I manage to solve the problem.

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Wednesday, August 3rd, 2016 AT 11:09 PM

KEN L

MASTER CERTIFIED MECHANIC
43,048 POSTS

Please let it know what happens so it will help others

Best, Ken

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Wednesday, August 10th, 2016 AT 11:32 AM

STAR 2000

MEMBER
3 POSTS

The temp sensor switch was replaced and the problem still persists.I plugged the switch back the fan cuts the operation.

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Tuesday, August 23rd, 2016 AT 2:32 AM

SATURNTECH9

MECHANIC
30,869 POSTS

The computer driver is good and the fan relay and wires to the fan are good. Your going to have to get a code reader that can read live coolant temp and compare that to actual coolant temp. Where was the sensor located you changed?