Radiator fan not working properly

IRNSH117

MEMBER
2002 TOYOTA CAMRY
2.0L
4 CYL
2WD
AUTOMATIC
180,000 MILES

Radiator fans not coming on even when reaching normal operating temperature (on the dashboard gauge) Fans only comes on if the connector to the coolant temperature sensor is removed (unplugged) when the engine is cool and also when it reaches operating temperature. On another note, there's also no thermostat on the cooling system. I don't really need it because of the climate I'm living in. But is it possible that that is what's causing the fans not to kick in? Because it already reached operating temperature on the gauge. Shouldn't the fans kick in?
Note: the car hasn't overheated yet, no signs of overheating, but I need to know why the fans are not coming on. Thanks

6 Replies

IRNSH117

MEMBER
4 POSTS

Note: both fans are working when the A/C is turned on, but never comes on when reaching normal operating temperature (without A/C).

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Friday, January 28th, 2022 AT 4:27 AM

SQM

MECHANIC
6,383 POSTS

Hello,

If a vehicle does not have the thermostat, it will not reach the proper operating temperature.
So, if that does not happen the coolant temperature sensor will not send the signal to the ECM to turn on the fan.
When the sensor gets unplugged, the ECM sees an open circuit and turns on the fan as a safety measure, as it does not know the temperature of the engine.

The operating temperature on this vehicle is 203F
So, it is possible that the vehicle might not be reaching that temperature and the ECM does not see any reason to turn it on.

And fans will come on with A/C, to provide proper cooling, it is a normal operating procedure.

https://www.2carpros.com/articles/how-a-coolant-temperature-sensor-works

The coolant temperature sensor can be tested, by checking the resistance.

I have attached the test procedure for the sensor below.

Please let me know if you have any questions.
Thank you.

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Friday, January 28th, 2022 AT 7:25 AM

IRNSH117

MEMBER
4 POSTS

So, you're saying that even if the temperature gauge reaches the middle between hot and cold, without the thermostat the fan won't come on?
The engine type is a Toyota 1az fse (Caldina 2002) not a Camry, couldn't see Caldina on the selection so I just put Camry.

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Friday, January 28th, 2022 AT 1:41 PM

SQM

MECHANIC
6,383 POSTS

Unfortunately, we don't have access to the technical data on the Caldina, so I cannot provide the exact data of the operating temperature.
But regardless of the thermostat, unless the coolant reaches its operating temperature, the fan will not come on. The only exception would be if you turn on the A/C or even max heat.
So, if you are not experiencing any overheating, it should be just fine.

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Friday, January 28th, 2022 AT 2:02 PM

IRNSH117