THERMO FAN IS STUCK ON EVEN WITH IGNITION OFF

f the engine shows signs of overheating, stop and look to see if the fan is working. With the type operated by the Connect the motor feedterminal to the live terminal onthe battery.

Check a fan motor for faults

Fan motor with the thermo-switch lead disconnected and test lead connected to the battery.Look at the battery, and take off the wiring terminals to the motor or disconnect the plug. Free the wires from clips or other fixings on the fan
A new motor is supplied without a fan, which must be refitted from the old one.The motor and fan normally come off as an assembly, but you may also have to remove the shroud and sometimes the radiator.
Separate the components. Clean the parts that are to be reused, simply by degreasing or even by repainting.
Checking the new motor When you fit a replacement motor, check it by connecting its leads directly to the battery. Be sure to connect the positive (+) and negative (-) leads to the corresponding battery terminals.Take care - the motor will kick as it starts and there will be a large spark when it is connected.
Checking the switch for faults A thermo-switch with push-on connections. The switch is threaded and has a sealing washer which must be renewed.If the fan motor is not at fault, leave the ignition switched on, take the connections off the thermo-switch and briefly touch them together.
If the fan motor now works, the switch is faulty. If it does not, check to see that there is current flowing to the switch by using a circuit tester on the feed wire to the thermoswitch.
Touch the leads together to bypass the switch.If the tester does not light, trace the lead from the thermo-switch back to its power supply; the car handbook may have a wiring diagram
A detailed drawing showing the location of electronic components and devices that are connected together in a circuit.
.If the tester lights, trace the lead from the thermo-switch through to the relay and check the terminals for tightness and cleanliness. Clean and tighten as necessary. Changing a thermo-switchThe thermo-switch is normally located in the radiator bottom tank, in the How to flush an engine radiator) until the coolant is below the level at which it is fitted. Catch the coolant in a clean container if you plan to reuse it. If a rubber cover is fitted over the back of the switch, ease it off, then disconnect the electrical connections.
The switch can now be unscrewed from its mounting point with an appropriate spanner. It may, however, be very tight, so take care not to distort the surrounding metal if it is fitted in the radiator bottom tank. Always fit a new sealing washer.
Checking the relay for faultsWith the ignition switched on, short-circuit the thermo-switch by putting a screwdriver across its two terminals; do not disconnect the leads. You may be able to hear a click from the relay as it operates. Test for current with a test lamp or circuit tester at the 'live' lead to the relay - again with the ignition switched on.
If there is current here but, when the thermo-switch is bypassed, none at the terminal for the fan-motor lead, the relay is faulty and must be replaced.
Checking the T-piece On the Datsun Cherry the thermoswitch and connections are in a T-piece on the bottom radiator hose, so look there if the switch is not on the radiator.

As I don't know which car you are referring to, I can only try to point you in the right direction on where to look. it could be on the radiator, cylinder head or thermostat housing or even in one of the water hoses. just look for something that has 2 wires connected to it that is in the water circuit. to test your fan once you find the switch, shorting out the two wires will normally start the fan (with ignition on) if the fan starts, then replace the switch, if it doesn't check the fan connections

The fan circuit consists of a 30 amp fusible link and a relay in the engine compartment fuse/relay block and the thermo-switch on the little coolant manifold near the driver side end of the engine. The relay is the one on the far right side with the fusible link just below it. I would question the thermo-switch first. To test the circuit you can short the wire that goes to the thermo-switch to ground, with ignition switch on, and the fan should run. It not then check and relay. See the attached diagram for thermo-switch location. Do not take the part numbers on the diagram for gospel. I drew this up several years ago. I do not have my Camry so I cannot totally verify the above. I tried to post an answer several days ago but was not logged in at the time and they would not post it!

hi there . there are lots of causes. head gasket. blocked radiator.
air lock. stuck thermostat. check that your fan is actually switching
on and off. if not check the thermo switch on the engine.

Disconnect the electrical at the top. Sometimes you can get the fan out and then the shroud-due to limited space. They would both come out from the top.
We mechanics will tell you to test the fan motor with jumper wires from the battery before you decide to pull it off. On most cars, the computer turns the fan on through a cooling fan relay. On your '87, it is possible that a thermal switch on the radiator may turn the fan relay on at a set temperature. One would have to see a wiring diagram.

Just looked at a diagram: If your car is fuel injected, check fuse #13, a 15 amp blue fuse. And same if carbureted, fuse #13-this fuse is for the relay and the fan motor. If carbureted, also check fuse #20-a 20amp fuse.
There are no computer controls for the fan on an '87. there is a thermo switch-at a set temperature, the switch will close-completing the ground path for the fan motor. There is also a radiator fan timer switch, tied in with the thermo switch and the air temperature sensor.
Sound complicated? Well, it is, even with no computer controls. If the fan motor is good, check or replace the thermo switch. Be sure and check those fuses, also. If no help, a tech will probably have to diagnose it.

never ever wire to the ignition or other EFI parts
no car model stated, no year, and no engine option type, size etc.
A SUZUK, something...
the cooling fan wires to ground and power via a thermostatic switch
best is to wire it to IGN1, feed at the ignition key .
using an inline fuse.rated for you r fan draw.
if you trust that new switch (id not) some wire it to the battery
but if it sticks on , it will drain the battery.

post car spec. what car, so i can tell you exact wire location.

locate the thermo sensor wich activate the fan's.Remove the plug and bridge out the two wires with only the ignition on.If the fan comes you need to replace the thermo sensor. If the fan still dont work then you have a wiring or relay problem.If the relay is faulty the same taes can be done as on the sensor. Find the relay and match the wiring colour that goes to the fan.On the relay harness you must test for two power supplies and bridge the one power supply to the fan wire.If the fan work;s and you do find two power supplies you only need to confirm if the wire from the sensor to the relay has continuity.If the wire is fine then you know that the relay is faulty.

I would check the fan relay first.

Check the relay for your thermo fan, should be in the main fuse box under the bonnet. Often when they heat up the fault presents itself. Other than that your thermo fan might be faulty.

The thermo switch is fitted into the radiator low down on the left side (when sitting in drivers seat). It should have 2 thick wires going to it. If these are pulled off and joined together the fan should run continuously, even with the ignition switched off. It is reasonably easy to change if you have the correct size ring spanner. Dont forget to refill the radiator with antifreez when you have finnished. the part is readily available from most after market parts suppliers