(Car) radiator fan always on (solved: just need to fix it)

[DrDonnyBrago]

Hi,

The radiator fan on my car (1997 2.0 GSD toyota corolla) is always running - from the second I turn on the ignition...

I have checked the relay with a multimeter and a wee 12v power source and all is well as far as I can tell. What should I check next? I assume there is a temperature sending unit or something, where would this be located and how do I check it?

Cheers in advance.

[stonesie]

If you have the AirCon switched on then it will run the fans to keep the condenser chilled

[Casper]

Temp sender should be on the side of the rad on the inside.

[Odie]

is it causing any problems?
if it aint, leave it alone.
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[Casper]

Now i think about it. I had an old Datsun and the fan was on all the time it just spun faster when needed. Could this not be the same set up?

[DrDonnyBrago]

I've had the car for a few years, it started doing this about 3 months ago but I haven't got round to having a proper play with it yet.

Not too concerned in summer where it may appreciate the extra cooling but I don't really want it doing it all through winter as the engine will take ages to warm up etc etc.

I'll try and find the temp sender later .

Oh and it doesn't have A/C.

[stonesie]

https://www.corolland.com/repairs.html

Have a look at that, the temp sensor should be on the side of the cylinder head above the gearbox, the most simple test i can think of is to simply un-plug it with the fan running, if the fan keeps running then its most probably the relay, if not then a new sensor is worth a try.

[WD Forte]

Ditto the 'disconnect the rad switch' idea
As they are either On or Off, rad/fan temp sensors are often bimetal switch affairs and the contacts have been known to fuse together.
Engine temp sensors are commonly NTC resistors whose resistance drops as they heat up and dont suffer the same way.
Rad/fan switches are often attached to the rad body or a main hose.
Dont confuse it with the temp gauge sender.

Dont have a WD for the car but typically, when the switch gets to a certain temp the bimetal strip distorts and closes the contacts
this in turn gives the relay coil an earth path which actuates the relay
and runs the fan.

With the connector opened you can emulate the switch by shorting the two wires together and see if it operates the fan
If it does, you know the rad switch is faulty
If it doesnt
Its possible but less common for the relay contacts to fuse together
but a continuity test on the power contacts will tell you if thats happened.

the above is what you often find, it may have a much more complex system for all lI know
I havent had a car in years I either ride bikes or drive scabby
diesel transits
HTH
____________________
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[DrDonnyBrago]

[DrDonnyBrago]

Sorted (almost) - there is a hose leading from the top of the coolant overflow reservoir that appears to have been dripping down onto the thermoswitch and part of the radiator. The fins in contact with the coolant have basically dissolved and are flaking away whilst the wires leading to the thermoswitch have corroded, one has broken off completely.

I didn't even think coolant was corrosive . Presumably the hose that has been dripping is supposed to be an air vent? must have a blockage somewhere to cause the coolant to come out of there rather than return to the reservoir.

Anyway looks like I need to wire a new connector in, I have attached some pics - anyone know what these things are called so I can source a replacement, or is it likely to be a toyota jobby? Actually, can they just be pulled apart and reused?


Thanks .

https://i1015.photobucket.com/albums/af271/DonnyBrago/DSC06150.jpg

https://i1015.photobucket.com/albums/af271/DonnyBrago/DSC06149.jpg

https://i1015.photobucket.com/albums/af271/DonnyBrago/DSC06148.jpg

https://i1015.photobucket.com/albums/af271/DonnyBrago/DSC06147.jpg

https://i1015.photobucket.com/albums/af271/DonnyBrago/DSC06146.jpg

[swampy]

I had a similar problem once on a Renault Espace. The thing you have there is a plug connector, may well only be Toyota only. I cut the plug off on the renault,and then crimped two teeny female (well three in the Renaults case) spade conectors onto the wires, then pushed these onto the pins on the fan switch. Add a bit of insulation tape and voila, all was well......
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[WD Forte]

The blade connector idea is deffo worth a try, some smaller speaker terminal size ones (4mm) may do it
you dont HAVE to use the funny shaped connector, you just need good reliable contacts

The connector is an unusual shape.
Toyota might sell them and the terminals. (maybe)
it may be common to jap cars.
Or
Its possibly fixable
During assembly the wires are crimped on the cable ends and the terminals
pushed into the connector until they latch.
It may be possible to use a small thin probe to unlatch and withdraw the terminal
if so, you could clean out the remnant, then solder a new bit of cable on and fix it to the existing wire
and re-latch it.
Done this myself on odd, or hard to get connectors.
Or
A Breakers may let you hack off the connector and cable from a scrapper and you could patch that in

personally I'd try the blade terminal idea meself for speed and
cheapness

I assume the fan does not come on with ignition now?
It shouldnt, I'm slightly puzzled how a broken cable made the fan run all the time.
____________________
bikers smell of wee

[finpos]

You can usually push the pin back out of the connector. Look carefully how it plugs onto the pins on the radiator, they will go either above or below the metal bit you can see at the end of the plug. You need to push a very thin screwdriver into THE OTHER SIDE of where those pins go. You are trying to release a tiny tab that digs into the plastic. You can then solder the wire back onto the pin and push it back in. Solder it very carefully, if you put a huge blob on there it'll never go back in the hole.

If all else fails, Just push the pin as hard as you can backwards out of the connector. You will bend said tab doing this, but you should be able to fix it back into place.

f.

[DrDonnyBrago]

Cheers for the suggestions, will have a hack soon. I should be able to figure something out. Thanks all .

[DannoXYZ]

[Nobby the Bastard]

Fuck me ragged. One post in 2011 and one post in 2020. That's a very long game...
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[arry]