QuestionQUESTION: I have a 1994 dodge spirit. One day i was in slow stop and go traffic when i noticed my temperature gauge really hot and smoke started pouring off of my engine. So we jumped the radiator fan and it turned on fine. Then we figured it would be the fan control relay so i replaced that. Then to no avail it still didn't work. Then i went and replaced the temperature sensor plug, and it still gets ridiculously hot and doesn't turn on. So i was wondering is there anything else that would be preventing my fan from turning on? If short the relay the fan auto turns on so i can't figure out what would not be sending the relay a message.
ANSWER: Hi Andrew,
By 'jumping the relay' I assume that you jumped across its socket pins from the light green wire to the gray wire. If not let me know. That jump is essentially showing that there is normal power to operate the fan but that the relay is not closing as it should.
To activate the fan relay you need to have two things:
1) the actuation coil has to have 12v on the dark blue wire (which comes from the ignition switch when in the "run" position) and that you could test by seeing if you have 12v on that wire at the relay and if not then check to see if fuse #8 has 12V on it because it too is fed from the same section of the ignition switch, and
2) the other end of the actuation coil has to be grounded by the engine controller (in response to the coolant temp sensor reaching its set point resistance which is the 'cue' to the controller to ground the dark blue/pink wire of the relay socket). So you could check if that wire is showing to be grounded when the engine temp is around 215F; also if the AC is requested it will ground provided the AC clutch is engaged and there is sufficient coolant in the system, regardless of the engine temp. So see how those two actuation coil wires are behaving and let me know.
Roland
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QUESTION: Hey Roland,
Thanks for the response. We tested the dark blue wire and it read 12v. Then we tested the dark blue/pink wire and it wasn't grounded when we had the air on. But we grounded the wire physically and the fan still didn't turn on. So i was just wondering what the red/white wire does? I know the green one runs to the fan but what about the adjacent wire?
Thanks you so much,
Andrew
ANSWER: Hi Andrew,
The wiring diagrams don't show there to be a red/white wire at the relay. When you ground the dark blue/pink wire did the relay click? If not then the relay is not working to close the power wire switch points to the fan motor. The power wire should have 12V on it from the battery (thru a fusible link, orange) and then when the points of the relay that source is connected to the light green wire that goes to the fan. If you can tell me where the red/white wire is attached to maybe I can figure out what it is for. It may be a modified circuit.
Roland
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QUESTION: Hey Roland,
Sorry its not a red/white wire. Its a red wire. The green wire when fed a proper 12v it turns the fan on as it is supposed too. Also when you connect the green wire with the blue wire the fan turns on also.
Anyway when i grounded the dark blue/red wire there was no clicking noise so the relay must not be engaging correctly. That's why i was wondering what the last wire (red) was for?
AnswerIf the red wire is the fourth wire lead at the socket, then it too should be carrying 12V from the battery on gray wire (not a red wire). I suspect that one of the fusible links (orange in color) which you will find behind the battery in a multi-fusible link harness is blown, and that someone previously attached this red wire to something else as a 12v supply for the fan motor relay. So I would try to find the orange link and pull on either end and if it comes apart that means it is blown. I would then replace it and if you can find the gray wire attach that between the end of the orange link and the fuse socket that now has the "dead" red wire on it (I assume that it is showing no voltage, correct?) It may be that the relay is closing, and you don't hear it. You could check to see what the resistance is between the red wire and the light green wire (it should be infinite) and then when you ask for AC it should drop to 0 ohms which would be a sign that the relay points are closing.
The fact that the fan runs when you hook the green wire to the blue wire is not surprising. That blue wire is a low current 12v supply for the relay's actuation coil. It is not meant to also power the fan. The pin to which the red wire is attached is supposed to have a separate 12V supply gray wire from the orange fusible link as the source of the fan power.
Roland
