Cooling fan not working?

Tiny
BLACKOP555
  • MECHANIC
  • 10,371 POSTS
Sounds like the relay to me! To test let the engine get to operating temperature then check for voltage going to it, if there is and none is leaving it change the relay!
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Sunday, October 25th, 2020 AT 11:38 AM (Merged)
Tiny
ZHENIASTOLI
  • MEMBER
  • 2 POSTS
  • 1994 TOYOTA COROLLA
Engine Cooling problem
1994 Toyota Corolla 4 cyl Front Wheel Drive Automatic 268k miles

replaced fan switch, fan still will not turn on when engine gets hot. It does work when A/C is turned on.
It also comes on when fan switch is disconnected.
Fan relay seem to be working.
There is another sensor with 2 wire connector should I try to replace that as well?
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Sunday, October 25th, 2020 AT 11:38 AM (Merged)
Tiny
BLUELIGHTNIN6
  • MECHANIC
  • 16,542 POSTS
Test the engine coolant temperature sensor, that is probably the sensor you are speaking of.
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Sunday, October 25th, 2020 AT 11:38 AM (Merged)
Tiny
ZHENIASTOLI
  • MEMBER
  • 2 POSTS
I've replaced Temp Sensor as well just to test it (from another used engine) Still engine almost reaches HOT setting on the dial and coolant begins to fill overflow tank.
T-stat is working OK heater blows very hot air.
Could I have bad Fan Switch. They are both located in the same T-stat housing.
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Sunday, October 25th, 2020 AT 11:38 AM (Merged)
Tiny
BLUELIGHTNIN6
  • MECHANIC
  • 16,542 POSTS
Did you replace the fan switch with a new or used one? It could have been faulty replacement but most likely there is something else going on, perhaps bad wiring to fan or one of the sensors/switches
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Sunday, October 25th, 2020 AT 11:38 AM (Merged)
Tiny
CHRISP83
  • MEMBER
  • 11 POSTS
  • 1994 TOYOTA COROLLA
  • 4 CYL
  • FWD
  • AUTOMATIC
  • 153,000 MILES
My car temperature used to always stay around the half way mark on the temperature guage. Now it keeps rising to close to the red. I noticed that the electric cooling fan is not coming on. I bridged the terminals on the relay that switches on the fan, now it runs constantly. This seems to help, although the temperature guage tends to occasionally rise above the "normal position" I've tried replacing the relay in the fuse box, but the fan still does not turn on automatically.
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Sunday, October 25th, 2020 AT 11:38 AM (Merged)
Tiny
MHPAUTOS
  • MECHANIC
  • 31,938 POSTS
There is a thermal switch that turns the fans on, check this, and make sure the thermostat is working and the radiator has a good flow rate, re post if you have trouble locating the thermo switch,

Mark (mhpautos)
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Sunday, October 25th, 2020 AT 11:38 AM (Merged)
Tiny
CHRISP83
  • MEMBER
  • 11 POSTS
Thanks for the info. Where would I find the thermoswitch?
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Sunday, October 25th, 2020 AT 11:38 AM (Merged)
Tiny
MHPAUTOS
  • MECHANIC
  • 31,938 POSTS
Hi there,

I will see if I can post a pic for you. But from memory they are near the thermostat on that model will check it out.

Mark (mhoautos)
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Sunday, October 25th, 2020 AT 11:38 AM (Merged)
Tiny
CHRISP83
  • MEMBER
  • 11 POSTS
By "THEY" do you mean there is more than one?

I noticed 2 switches that I suspect could be the thermoswitch.

First is located on the thermostat housing and has one wire coming out of it.

Second one is mounted in the actual engine block and has 2 wires connected to it.
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Sunday, October 25th, 2020 AT 11:38 AM (Merged)
Tiny
MHPAUTOS
  • MECHANIC
  • 31,938 POSTS
Hi there,

The switch with the single wire will be the temp gauge sender. The other should be the thermo fan switch

Mark (mhpautos)
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Sunday, October 25th, 2020 AT 11:38 AM (Merged)
Tiny
MMPRINCE4000
  • MECHANIC
  • 8,549 POSTS
If you disconnect the fan switch, the fans should run all the time. If they do not, then it would be a relay.

Another thing to check is to turn on the AC, the fans should run at a lower speed, if they do not then again it is one of the fan relays or the main engine relay.
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Sunday, October 25th, 2020 AT 11:38 AM (Merged)

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