Electric fan.

[Buzzard67]

Hi everyone.
Iam looking for some help on my electric fan. The engine has two electric fans, one to cool the engine and the other is for the trans or ac ?
The fan that is not turning on is the one that cools the engine.(middle to passenger side under the hood).
Q: Does the fan have a preset temp setting before it starts up. Because it has not been over 45 this whole winter/spring.
Q: I checked and replaced the relay under the hood. Made no difference.
Q: I checked all the fuses under the hood and drivers side, all still good.
Q: There is another relay under the glove box passenger side. Do any of these control the engine fan,because I did nothing to the fuses or relay by passenger side.
Q: Is there a wire harness that I can follow from the fan to fire wall or Battery?
Q: Is there a way I can just check the fan to see if it works at all.

The fan worked very well all winter and then it just quit.
Any help would be great.
Make:Toyota
Model:Tercel DXL Automatic 4x4
Year:1984

Thank you Bill (Minnesota)

[marlinh]

There is a temp switch on the bottom of the radiator that turns on the fan. You can check if it functions by disconnecting that plug with the key in the on position. Is the thermostat stuck open?

[dlb]

like marlene says, with the key in the 'on' position, the fan should come on when you disconnect the plug from the bottom passenger side of the radiator. if the fan comes on, the fan is good. then the problem is most likely in the temp switch in the rad, which is easily swapped out after draining the coolant.

what does your temp gauge read? the fan usually comes on when the gauge gets up to about 2/3. if the fan is not coming on even when the temp gets that high, i would suggest to swap the temp switch.

[Buzzard67]

Thank you ! It was the temp switch at the bottom of the radiator. The male end of the plug worked its way off and I just plugged it back in and let my car get up to running temp. The fan started up.
Very happy about the quick fix.
Thank you "Marlinh and dlb".
I love these Tercels 4x4.
Latter Buzzard

[teranfirbt]

I know your problem is fixed, but for everyone's info, there are actually 2 fan switches, one at the bottom of the radiator and one at the top in the aluminum coolant outlet from the head.

[irowiki]

That's not a fan switch, that's the temp sensor for the computer!

[Gottolovem]

Computer?
thermal switch has a mind of its own

[irowiki]

Yeah. There's one sensor on the block (head?) that powers the temp guage. The other temp sensor on the coolant thing with the TVSV goes to the computer. On AT cars there's one more sensor, on the head I think.

[Gottolovem]

When you say computer are you refering to the relays in the main fuse box?
Perhaps we have a different difinition of a computer?

[irowiki]

The emission computer

[teranfirbt]

That's definitely a fan switch, at least it is on mine. At one point (years ago...) I was using one to run the fans on my Celica.

[irowiki]

That may be the case on a Celica, but is definitely not the case on a Tercel! The switch at the bottom of the radiator is the only thing that powers the radiator fan:




The sensor you are talking about, on the piece with the TVSV, is highlighted in yellow:



The last two, usually on the head/block, are the water temp sender, and the water temp switch (for AT)

[Petros]

yes, the temp sender for the gauge is on the front of the head, the one on the coolant outlet with the large green connector goes to the "computer". It is a rather primitive computer, basically a number of on/off relays that controls the low/intermediate engine speed fuel/air mixture through the EBVT (what ever it is called, it bleeds air under the carb depending on water temp, engine speed, air temp, etc). It was the last straw for carbonated engines, all went to EFI after about 1988-1990 because of the better mixture control, which likely actually saved manufacturing costs because it uses far less parts, and it worked much better than the carb.

[teranfirbt]

Hmmm, interesting, and here I was thinking it was for fan control.

[irowiki]

On a slightly less "budget" car, yeah I can see the computer taking some control of the fan too!