Electric Fan Problems

Dyno12 · Jun 19, 2014

Hello I've ran into a snag and I'm out of ideas. I have flexalite gcooling fans that worked great til 2 weeks ago. Tested fans to power they work. Bought a new relay and nothing. Just bought a new temp switch that's installed into water pump and fans r still not kicking on. It's a 93 5.0 very simple setup and can't seem to figure it out. Aftermarket relay setup has constant power the voltage is good when I turn key on for the ignition power and there's voltage at the single prong temp switch. Problem is when I hit 180 fan will not kick on goes to 220 then I turn the car off. I've tryed 3 relays checked the 4 power wires and ground is solid what's going on.?

jrichker · Jun 19, 2014

Where does the fan draw its power: Is there a fuse in the power feed for the fan?

Typical electric fan circuit. Yours may be different...

If you are good with electrical stuff (90% of the people here aren't), build your own controller. The numbers on the diagram (#86, #87, etc) refer to the numbers on the bottom of a typical automotive relay.

Note that the temp sensor in the diagram needs to match the thermostat in your engine. The preferred arrangement is to have it open about 5 degrees above the thermostat.

To allow the ignition switch to control the fan so that it does not run when the ignition is off, connect the relay contact #86 to the red/green wire on the ignition coil or to the red/yellow wire on the coolant level sensor.

Dyno12 · Jun 19, 2014

Checked out the diagram and that's basically what I have. Main power is wire right from starter solenoid 12v. I have my ign switch power to relay witch does turn on and off with key to 12v. There is the wire that runs to temp sensor that has 12v when car is on witch I'm questioning and my power wire to the fans. Temp sensor is single prong 185 deg on and thermostat is 180

Dyno12 · Jun 20, 2014

Ok checked I'm getting power to 86 but it's also going through relay to 85 witch is showing it should be a ground

jrichker · Jun 20, 2014

Dyno12 said:
Ok checked I'm getting power to 86 but it's also going through relay to 85 witch is showing it should be a ground

The diagram is similar...not necessarily the same...

85 and 86 are both the relay coil and you can interchange them with no problem. One side is power and the other side is ground. If the there is power but no ground, the relay coil does not make the relay contacts close. Current has to flow from power to ground to make the relay work.

rbohm · Jun 20, 2014

ok so you are getting power to the relay on the side that activates the relay, but are you getting power to the relay on the side that carries the load? and then are you getting power through the relay to the load itself? also test your temp switch as well to make sure it is closing its circuit at the right temperature.

Dyno12 · Jun 20, 2014

Yes my ignition power is coming on at 85 and it's feeding through the relay switch out 86 witch is wire going to my temp sensor switch and I also have my constant power I think something is wrong with the fact temp sensor wire also has 12 volts

rbohm · Jun 20, 2014

the temp sensor wire should have 12 volts to it, how else does the relay energize when the temp sensor closed the ground? but if you energize the relay, does the fan come on as it should?

Dyno12 · Jun 21, 2014

No it does not come on .I have to be missing something the fan comes on if I jumper from constant power to the load side but once i put the relay in nothing happens. Sorry if I'm misunderstanding but what I'm getting is the temp sensor wire should have 12v to it and when it reaches temp the sensor grounds out tripping the relay? I have applied a direct ground to the temp wire and the fan still doesn't come on.

rbohm · Jun 21, 2014

Dyno12 said:
No it does not come on .I have to be missing something the fan comes on if I jumper from constant power to the load side but once i put the relay in nothing happens. Sorry if I'm misunderstanding but what I'm getting is the temp sensor wire should have 12v to it and when it reaches temp the sensor grounds out tripping the relay? I have applied a direct ground to the temp wire and the fan still doesn't come on.

then you have a relay issue. or the wire that triggers the relay is bad.

Dyno12 · Jun 22, 2014

We'll here's n update ran new wire and changed location of the relay ignition wire. Put the relay on a manual switch. It's working! Jump in the car to take it out last night. I have no lights in the front now no parking no headlamps no turn signals. But the rear lights work. My guess is I knocked a ground off when putting in new wire to fan relay..?

rbohm · Jun 22, 2014

arent electrical issues fun?

Dyno12 · Jun 22, 2014

God I'm loosing it

jrichker · Jun 22, 2014

Electrical problems are only difficult if you don't understand how electricity works.

Automotive circuits are mostly simple stuff: a power source, a connection path, a control device, a load, and a ground.
The battery/alternator is the positive power source.
The wire and fuses are the connection path.
Control devices are switches, relays and sensors.
A load is a light, motor, solenoid, relay coil or heater element.
In automotive circuits, grounds are the return path so the electrical power can flow from the load to the negative side of the power source.
Electricity flows like water:
Voltage is like pressure,
Current in amps is like volume,
Resistance is like the kink you put in a garden hose to decrease the pressure or volume.
Power is pressure multiplied by volume or voltage multiplied by current (amps)

Digest that, and you just got the first 3 days of Electricity 101.

Use some jumper wires (connection path and ground) to hook up a switch (control device), a battery (power source), a light bulb (load). Now make the light turn on and off with the switch.

That's the electrical lab for the first week of Electricity 101.

For free automotive electrical training, see Automotive Training and Resource Site .
Also see http://www.the12volt.com/relays/relays.asp
I have personally reviewed the material and it is very good. If you are new to automotive electrical troubleshooting, I highly recommend you spend a hour or so going through the material. You'll save at least that much time troubleshooting problems.

No lights on one side or both sides?
One side inoperative is likely to a bad or missing ground wire that attaches to the top of the radiator support.

Both sides inoperative is probably a fuse.
Diagram courtesy of Tmoss & Stang&2birds

Fuse box layout

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