When does your radiator fan switch on?

[tooldude]

All EVTM's, 1990-91-92-93, clearly show the coolant temp sensor in the thermostat housing and the coolant temperature switch in the cylinder head. The 1988-99 EVTM's depict the sensor incorrectly to the right of the distributor but correctly at the end of the engine, whereas the view for the switch is completely ambiguous and appears to be at the end of the engine rather than the side. The argument is pointless though because pulling one wire at a time will either disable the temp guage or activate the fan. Also, the fan relay is depicted as SPST because that is all the circuit needs. A double throw relay has two sets of contacts. The relay coil and it's terminals are not considered throws. Misunderstandings about these kinds of points can lead to confusion about circuits.

[TorqueEffect]

All EVTM's, 1990-91-92-93, clearly show the coolant temp sensor in the thermostat housing and the coolant temperature switch in the cylinder head. The 1988-99 EVTM's depict the sensor incorrectly to the right of the distributor but correctly at the end of the engine, whereas the view for the switch is completely ambiguous and appears to be at the end of the engine rather than the side. The argument is pointless though because pulling one wire at a time will either disable the temp guage or activate the fan. Also, the fan relay is depicted as SPST because that is all the circuit needs. A double throw relay has two sets of contacts. The relay coil and it's terminals are not considered throws. Misunderstandings about these kinds of points can lead to confusion about circuits.

Well the EVTM is clearly wrong about which one is which. Just saying.

[bravekozak]

Bad EVTM.

[tooldude]

If it turns out that Ford/Helm never corrected an error like that for 5 years, I might be able to get a teeny mental surprise but not enough for anything verbal. Now I'm going to check mine to see what's up...well, later.

[crazyrog17]

I see what you're saying about the SPST relay tooldude, thanks for the clarification. The EVTM shows it provides a circuit to ground instead of voltage like I'd stated. Good to know, you can look for power at the plug if the fan's not working to rule out some problems.

[tooldude]

I pulled the wire at the thermostat housing, turned on the key and the fan started running (very cold car); pulled the wire at the head and nothing to the temp guage. Like Torque said, the EVTM is bass ackward.

[bravekozak]

What a coincidence. I just tested an 89 wiring harness. The Y/W wire with the bullet connector has continuity to the white instrument cluster connector for the temp gauge. The GR/R (different color in 89) wire with the spade connector is for the fan relay. Thank you Ford Motor for the error. What Ford labels the temp sender is really the cooling fan switch. At least I will be able to sleep tonight without having any nightmares. If I am not mistaken, the threaded hole in the thermostat housing, for the cooling fan switch, is straight thread. The seal is done by the O-ring washer. Please verify.

[m3t4lm4n222]

The sensor in the video above, if I unplug it, my fan turns on. I should replace this? I'm taking it back to my dads shop on Tuesday, considering I had the fan switch and temperature sensor replaced.

[crazyrog17]

No, that's what is supposed to be. When the coolant gets above the temp that necessitates forced cooling, the switch breaks the path to ground.

[m3t4lm4n222]

Yes, but the initial problem I am having is that it doesn't appear to be kicking in. Even when displaying the temp level in this picture, the fan remains off when plugged in. Is this above 207F?

IMG_20140124_133549_467.jpg

[tooldude]

"Yes, but the initial problem I am having is that it doesn't appear to be kicking in. Even when displaying the temp level in this picture, the fan remains off when plugged in. Is this above 207F?" *You will have to check the temperature on the thermostat housing, as either the temp guage is displaying wrongly or the coolant temperature switch is defective/out of spec.

[crazyrog17]

My cooling fan kicks on just above half on the gauge. I don't know why, but I smile and pat the dash every time it does.

[TorqueEffect]

I would say replace the switch in the thermostat housing. Don't use Teflon or sealant because no ground can be made if it is used.

Sent from my SPH-M950 using Tapatalk

[m3t4lm4n222]

That may be the issue. I checked the new switch in the thermostat...sure enough it's got some sort of sealant around it.

However, I have another question. Today I noticed my car was getting hotter, so I turned it off, unplugged the plug from the switch, then turned the car on and noticed my coolant gauge was still functioning. Should it still be functioning when it's unplugged.

Any idea if the temperatures being displayed on my temp gauge could cause any damage to the engine? I'm worried about blowing or cracking a head gasket. Or would I have to be closer to the red for that to occur?

[TorqueEffect]

That may be the issue. I checked the new switch in the thermostat...sure enough it's got some sort of sealant around it.

However, I have another question. Today I noticed my car was getting hotter, so I turned it off, unplugged the plug from the switch, then turned the car on and noticed my coolant gauge was still functioning. Should it still be functioning when it's unplugged.

Any idea if the temperatures being displayed on my temp gauge could cause any damage to the engine? I'm worried about blowing or cracking a head gasket. Or would I have to be closer to the red for that to occur?

The switch in the thermostat isn't for the gauge, the one with the bullet connector on the head is. At the end of my video I very very briefly look at it, that is for the gauge.
If you disconnect that one and you still have a working gauge, then I have no clue, because that SHOULD be the temp gauge sensor.