Radiator fans do not turn on

[barred owl]

Hi folks, I've been having trouble with my 1994 Tercel running hot in stop-and-go traffic recently, and when I tried to fix the problem I realized that my cooling fans are not coming on. Things I've tried:

a) Replacing the fan relay in the fuse box. I noticed it was quite warm after the car was running so I swapped it out for a new one. But that didn't help.
b) Unplugging the Engine Coolant Temperature Sensor (I think.) While the car was running I unplugged the two-pronged green plug just beneath the distributor next to the radiator hose that I believe is the coolant sensor, but the fans did not come on. (When I tried to start the car with that unplugged it would not start.)
c) Checking the fuses. Everything looks normal.
d) Idling the car until it gets warm enough that the fans should kick in automatically. (Nothing.)

I understand from reading the forum that there is a temperature switch that often fails located somewhere near the bottom of the radiator (?), but I can't find it. If I find this and unplug it should the fans turn on?

Hoping for suggestions and info about where I can find that switch (and whether I correctly identified the ECT sensor). Thanks for your help.

[dlb]

hi barred owl. just a heads up that most users on this forum are not familiar with the post-1987 second gen tercels so bear that in mind when asking about any car-specific info. we're generally into the 1983-1987 4wd tercel wagons but many here will still help where we can.

on our older tercels, there is a wire that plugs into a switch on the bottom of the rad. the default setting for that switch is 'on' so if the ignition is in the 'on' position and you unplug said wire from the rad, the fan should come on. if it does, that tells you that the fans work but the switch needs to be replaced. luckily, that's easy. just drain the coolant from the rad into a clean container, use a wrench or socket to remove the old switch, put a new one in, and put the coolant back in the rad. while you refill the rad, stop occasionally and give the lower rad hose a few good squeezes. this helps to burp air bubbles out of the system. after the next few good drives, wait until the engine is cold and then check the coolant level at the rad cap and the overflow reservoir and top up as necessary.

if the fan does not come on when you unplug the wire at the bottom of the rad, something is wrong with the fans themselves or the power getting to them. could be a fuse or a bad ground.

that's how it is on our second gens, anyway. hope that helps.

[barred owl]

Hi dlb, thanks very much for your quick reply. I did notice that this forum was focused on the earlier models but it seemed that you folks were the most knowledgeable in general.

I did track down that switch (located underneath and behind the distributor on my model) and pulled the plug. Fans came on full speed, so now I know where my problem is. I'll get a new switch and then swap it out. Until the part arrives, though, I know that I can pull that cable to manually activate the fans if I get stuck in traffic.

Thanks so much for your help.

[dlb]

yes, if you are going to be doing all or mostly city driving you can just leave the switch unplugged so the fans are always on. you don't want to do that long term because it will wear out the fans but for a few days or even weeks would be fine.

[applewew]

yes, if you are going to be doing all or mostly city driving you can just leave the switch unplugged so the fans are always on. you don't want to do that long term because it will wear out the fans but for a few days or even weeks would be fine.

Mine ran like that for around 3 years until I bought it and replaced the sensor

[dlb]

yes, but all things wear out. by having the rad fan going every time the car was on for 3 years, it's now more likely that it will give up just that much sooner.

[applewew]

yes, but all things wear out. by having the rad fan going every time the car was on for 3 years, it's now more likely that it will give up just that much sooner.

That's what I'm hoping to not happen. It was the very first thing I fixed as soon as I got it. Now it hardly ever turns on. My work-home distance is around 4 miles top.