radiator fan..replaced relay and sensor

[taytay]

So my radiator fans won't come on by themselves but come on when the AC is on. Therefore my car overheats (needle goes to red) when it's sitting still with the AC off. I've done research on the forum and found out that they are wired separately. So I've replaced the "fan 1" relay and the coolant temp sensor but it has not solved the problem. When I unplug the sensor, the fans run all the time but that is not what I want, I want it to work correctly. The parts I used to replace the "broken" ones were used but were theoretically tested by the shop that sold them. Do you think that both of the coolant temp sensors I've had in are bad? What else do you think could be the problem?

p.s. It seems as though it takes a normal amount of time for the car to heat to the the normal position (middle) but once it starts going above the normal position towards the red, it goes really fast to the red. From a little bit above normal it will reach the red line within a minute...seems like that shouldn't happen but idk

'96 LE, inline 4

[toyomoho]

If the fan comes on when the plug is pulled off the sensor, the issue may be the sensor.

The switch is closed until the coolant temp reaches 194F, the fan does not run if the sensor switch is closed.

When 194F is reached the switch opens and the fan operates.

Yes, this is opposite of what one would expect.

When the engine starts to overheat turn on the AC, this will run the fans.

The rapid shoot up in temp may be due to the fan issue or a bad T-stat.

[new echo owner]

Which sensor did you replace? Which sensor did you unplug?

Like toyomoho said the cooling fans are turn on by the coolant fan switch which is located by the thermostat housing, when it is open or disconnected the fans come on. If the fans don't come on when the engine is hot but work with the A/C, then a very good chance you may need the coolant fan switch.

N.E.O.

[taytay]

I replaced the coolant sensor (coolant fan switch) at the bottom left of the radiator if you're standing up and looking down at the engine. And that is also the plug I unplugged and the fans came on. I replaced it with a used on tho, so that might be the problem or it could be something different..any ideas besides the switch?

[new echo owner]

Ah, silly me, you have a four cylinder, should have read more closely.

You can test the switch if you are not sure. Also did you check to see if the lower hose is hot, meaning that there is actually coolant circulating there. You may have a thermostat that is stuck closed.

N.E.O.

[taytay]

thanks for the replies..yeah the lower hose gets hot. Once it gets too hot then the temp gauge in the car goes up i presume. When I turn the ac on tho the fans come on and cool the car down. I've got a friend who's a mechanic so I think I'm going to bring it in to his and see what he says. I was trying to avoid that but what can you do.

[new echo owner]

If there is coolant circulating to the lower radiator hose and the cooling fan switch area, and the fan still are not coming on, there is a good possibility that the switch isn't functioning.

N.E.O.

[YoungEazy]

Im having the same issue with my car, I'm going to have to check that cooling face switch


thanks guys

[taytay]

I put in a brand new switch and relay, fans still didn't cycle on by themselves. Took it to my mechanic friend he put in a new thermostat and it still didn't cycle on. At this point I'm pretty pissed off and don't know what to do. I had a new radiator put in two years ago but we decided to try to blow it out anyways and then after the fans decided to cycle on! I'm not sure why tho.

Now, the temp gauge shows the car runs a little bit above normal when it idles for long while (even with the fans kicking on w/o the ac on) but when you rev it the temp drops back to normal.
Do you think it could be the water pump going bad?

[new echo owner]

On an I4, you can look at the water pump impeller when the thermostat is out, you can try that instead of taking the engine apart to check the water pump.

N.E.O.

[taytay]

Everything is running great now, I had a new water pump put in (and timing belt), my mechanic said the radiator fans weren't coming on because not enough water was flowing through the radiator. Thanks new echo owner for responses