I just bought a 98 Corolla LE. I noticed (after I bought it) that the cooling fans are always operating. Even this morning with a outside air temperaure of 21 degrees C (71 degrees F) my fans were running on the car as soon as I turned on the key.
Questions
1. IS there a default on the relays to the ON position?
-Assuming that is the case then I can suspect the relays.
2. If there is not default position ont he relays, where do I start? ... Ill need a wiring diagram for the cooling fan system.
That almost definitely sounds like a bad ECT switch or the electrical wiring/connectors leading to the switch. The switch is located on the thermostat housing on the front of the car. You can test the sensor with a multimeter to see if the swtich is bad or not, same way with the wiring - the sensor should show continuity when cold (i.e, from the electrical pin to the sensor body - below 181F (83C), should be continuity. If the is no continuity, the sensor is bad.
That almost definitely sounds like a bad ECT switch or the electrical wiring/connectors leading to the switch. The switch is located on the thermostat housing on the front of the car. You can test the sensor with a multimeter to see if the swtich is bad or not, same way with the wiring - the sensor should show continuity when cold (i.e, from the electrical pin to the sensor body - below 181F (83C), should be continuity. If the is no continuity, the sensor is bad.
So I take it the ECT switch is seperate from the temperature sensor... because the temperature gauge shows accurate readings.
The sensor (switch ) has continuity when cold... so that means I am at a realay or follow the line to the relay and make sure I still have continuity, unfortunately, I dont have a wiring diagram to tell me which plug is the switch plug from the sensor(switch)
Correct, the ECT switch (on the thermostat housing) is separate from the temperature sensor in the grille.
If there is continuity in the ECT switch when cold, chances are the switch is OK (have to verify by boiling the sensor to see that there is no continuity between the terminal and sensor body). Try shorting the connector running to the ECT switch to ground - the fans should not be running. If they are, possibly a severed wire running to the fan control or as you mentioned, a stuck relay.
The relays are in a junction box, right by the battery. Two sets of relays, one for each fan. I don't remember, but those relays might be bolted in from underneath - just tug on one and see if it pops out, if not, then it probably is secured in there. Don't force it too much, or you could crack/damage the relay.
Correct, the ECT switch (on the thermostat housing) is separate from the temperature sensor in the grille.
If there is continuity in the ECT switch when cold, chances are the switch is OK (have to verify by boiling the sensor to see that there is no continuity between the terminal and sensor body). Try shorting the connector running to the ECT switch to ground - the fans should not be running. If they are, possibly a severed wire running to the fan control or as you mentioned, a stuck relay.
The relays are in a junction box, right by the battery. Two sets of relays, one for each fan. I don't remember, but those relays might be bolted in from underneath - just tug on one and see if it pops out, if not, then it probably is secured in there. Don't force it too much, or you could crack/damage the relay.
The relays are plug in types from the top.... one is a a fuse/relay box and is labled "rad fan no1", the other is in another relay/fuse box and is labled "AC FAN".
I should also mention that yesterday was a very warm day here with temps approaching 31 degrees C (90 F), eeen though the temp gauge showed normal operating temp, the fans were NOT operating when I stopped the car in the driveway, so I presume that the switch was working at that point..... guess I should attack the relays eh?
Yeah, sounds like flaky relays. If the ECT switch is bad or the wiring is bad, the fans will constantly run, even come on when you turn the key to ON.
Funny, both of mine say "AC Fan" on the cover plate over the relays. Probably due to running changes over the course of the production run for this generation.
Yeah, sounds like flaky relays. If the ECT switch is bad or the wiring is bad, the fans will constantly run, even come on when you turn the key to ON.
Funny, both of mine say "AC Fan" on the cover plate over the relays. Probably due to running changes over the course of the production run for this generation.
It appears that I have more than two FANS!!!! I opened the hood again tonight and turned the ignition on, the fans started again and so I opened the one fuse/relay box for the rad fan and removed the relay, the two fans between the engine and the rad stoped, but I could here another fan running!!! I must have other fans in front of the rad
Oh ya thanks for the help BTW, it was quite the job putting that Alternator back on, I had to remove it just to get at the switch, and putting it back on was a real pain trying to get the bottom bolt hole lined up
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