Cooling Fans On When Cold?

[cookci]

hi

my cooling fans switchin on/off every 30 seconds or so and keep doing this from cold to warm. My thermostat has been changed recently and the car warms up in about 5 minutes (to half way on the guage).

any ideas what could be the problem?

cheers

christian

[chocka]

COULD BE A DODGY TEMPERATURE SENSOR?

WHAT'S THE TEMP GAUGE READING WHEN THE FAN COMES ON?

[GT4 BOOSTER]

i'd say the temp sensor in the radiator or where ever its located on a celica was at fault here.nothing to do with the thermostat for the dash temps.

[cookci]

the temperature gauge in the dash moves slowly from minimun to maximum (SORRY HALF WAY).

the cooling fans switch on and off all the way up to half way.

[GT4 BOOSTER]

that dont sound too good mate , is the engine overheating too , or just the dials going crazy ???

[cookci]

the dials not going crazy at all.

the fans come on when i first start the car!

basically my car is 100% fine except the cooling fans come on even when its cold.

[GT4 BOOSTER]

sorry i missed the half way in brackets , in that case it just sounds like the sensor in the radiator then , the wires should loop back from it upto the fan.or trace them back to the sensor from the fan.goodluck.

[cookci]

sorry i missed the half way in brackets , in that case it just sounds like the sensor in the radiator then , the wires should loop back from it upto the fan.or trace them back to the sensor from the fan.goodluck.

Np i added that bit at a later date anyway

[AlchemistsDen]

I have the exact same problem, my radiator cooling fans come on as soon as I turn the key in the ignition. Obviously the engine is not hot, its just sitting there!

Anyway I am going to change out the temperature sensor/switch, but my question is this....do I need to empty the radiator fluid before I change the switch? Am I going to get radiator fluid everywhere as soon as I pull the switch out?

[GT4 BOOSTER]

yes you will get wet , use the drain plug provided and pour it back in once ur done.

[AlchemistsDen]

What drain plug provided?

Where do I poor the radiator fluid back into? Do you mean in the resevoir or directly into the radiator?

[GT4 BOOSTER]

a white plastic plug in 1 bottom corner of the radiator or just catch it from where you take the sensor out of. , pour it back into the radiator

[AlchemistsDen]

Sorry, I am a little confused.

The temp sensor/switch is not located (as far as I know) on the radiator. It is located on the side of the engine block, at the cooling fluid return side.

Do I still need to drain the cooling fluid? If so, I might as well flush and renew the fluid.

[GT4 BOOSTER]

ahh the 1 near the throttle body , ok you only lose a small amount of water from there , you could drain some from the system first , then i suppose non will come from there.now i gottcha

[cookci]

I have the exact same problem, my radiator cooling fans come on as soon as I turn the key in the ignition. Obviously the engine is not hot, its just sitting there!

Anyway I am going to change out the temperature sensor/switch, but my question is this....do I need to empty the radiator fluid before I change the switch? Am I going to get radiator fluid everywhere as soon as I pull the switch out?

when u find the part number for the part can u let me know...

also if it fixes the problem

[AlchemistsDen]

Good idea! Thats what I will do. I will drain a small amount from the radiator and change the switch. Just so you know, I am attaching a picture with the sensor. This is a 1.8 engine 7A-FE from a 97 Celica.

Thanks again!

[AlchemistsDen]

Cookci, the part number in the USA is 83420-20040. This is the Toyota part number that they gave me.

I ordered it and it should come soon. I will let you know.

:hokus-pokus:

[GT4 BOOSTER]

83420 - 16040 is the st202 sensor part number.

[GT-Four NZ]

Are you sure that there isnt a switch unit on the radiator??!! Im pretty sure that the one that you are indicatin in the picture is the sender for your guage... very little to do with fan operation. There should be one in the bottom of the radiator (drivers side on my 185) that controls the fan... the drain bung requires a twist.. not complete removal and usually has a tube protruding down through the plastic engine tray which makes collection really easy... yes do this before removing the switch... and yes put it back in the radiator when the new one is installed. My fans (One found its way onto the intercooler run all constantly as i have got an override switch in the cabin... just seems to keep the air moving through the engine bay nicely. Try unplugging the switch before removing it... start the engine... the fan should run all the time... if this is the case then yeah get a new switch...

Happy fixing

[GT4 BOOSTER]

thats what i thought too , i just looked at mine and its right next to the radiator drain plug ,as i thought it would be.

my advice would be to wait until temp goes up disconnect the sensor you were going to change and look on the dash to see if the needle falls to zero , that way you know ur on a hiding to nothing changing that sensor you ordered.

if the car is a 17 digit chassis number i can take a look at it better for you on the toyota EPC And give you the part number you need.

[AlchemistsDen]

Thats good advice from both of you.

I will try unplugging the gage I was going to change and see if the temp falls to zero. Also, I will look for the sensor you are talking about next to the radiator switch.

It makes sense. The sensor at the output of the manifold should be telling the dash gage what temperature the engine is.

The fans should be controlled by the temperature of the coolant in the radiator, not the engine. Thus, it should be located somewhere on the radiator.

I will let you know what comes out of this situation.

:hokus-pokus:

[celicaste]

Hi i had this problem on my gen 5 and it ended up being a broken wire down to the sensor on the radiator not actually the sensor.If you remove the plug off the sensor and bridge the two connections with a link wire the fan should stop. if it doesnt it is the sensor at fault