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Posted 08 April 2013 - 11:29 AM
Posted 08 April 2013 - 11:37 AM
Posted 08 April 2013 - 11:38 AM
Posted 08 April 2013 - 11:39 AM
I just read about the thermo switch. Is this the coolant temp sensor or something else? There's only 1 plug going to my radiator.
The fan has a seperate thermo switch.
Posted 08 April 2013 - 01:55 PM
I ended up wiring the electric fan up to a switch for precisely this reason. In my case, the thermo-switch that screws into the radiator had failed, and would only trigger the fan when the gauge was within a needles-width of red. There are a couple other possible failures that could cause this as others have explained.
There are a couple ways to do it, I'll lay out how I set up the switch. Something similar to this should do the trick. Since it is part of the DC circuit in the car there is less need for worrying about direction of flow, if you get it backwards, it is easy to correct.
You will need:
- Wire of a similar/same gauge as what forms the pigtail coming off the fan. I cut open a defunct extension cord and took several feet of good wire from the middle. (the plugs were busted, but the wire was good)
- A switch that will accept that wire gauge. Stop in to your local hardware store with a sample of wire/the pigtail
- Some wire connectors. You will need both wire-wire, and wire-screw ones.
- Tool(s) to cut, strip, and crimp smaller gauge wire
- Screwdriver(s) as needed
- Wrench for whichever size bolts you need to adjust
Then approximate the following:
- Remove the battery from the car. There are lots of opportunities to start bad electrical events in this process, so I recommend removing the battery until you are finished.
- Cut the pigtail running from the thermo-switch to the fan, as close to the plug as you can. Strip both tail pieces as appropriate.
- Choose one of the wires in the tail, connect a length of wire to your chosen pigtail piece. Run the wire along the radiator (mine is 'trapped' in the little cavity all along the top of the rad), then along the inside of the quarter panel, and through the firewall into the passenger compartment near the brake pedal. You will see where the other wire bundles go through the firewall, just push this one through in the same spot.
- Give yourself about three feet of play *inside* the passenger cabin so you can put the switch wherever you end up wanting it.
- Come back and stand at the radiator fan again. Connect/splice a length of wire to the other piece of the pigtail, and run it along the same route as the first wire until you reach the battery. Use another wire-screw connector to fasten this wire to the ground post of the battery.
- Connect a length of wire from the hot post of the battery (wire-screw splice thingy, connected to the clamp, not the post) and run the other end through the firewall into the passenger compartment.
- There should now be two free/loose ends hanging in the passenger compartment (see #3 and #6), near the brake and/or clutch depending on your transmission. Wire these to the two fastening points on the switch. Which goes to which post on the switch is irrelevant.
- Double check that the pigtail has two wires connected to it, and that the battery has a wire on each post, and that two new wires go through the firewall and are connected to a switch.
- Replace the battery and test. If the fan blows the wrong way, simply switch the two wires at the pigtail (it's a good idea to have a second pair of splicer things if you got the crimping type). The fan will then blow the other way.
- Route the wires as needed to place the switch where you want it. There are several options where it can be placed. Secure the wires in the engine compartment so they don't get caught on any moving parts.
That should more or less do it in ten simple steps. It would be wise to include a body ground in there, you can simply snip the ground wire near a good ground point, crimp a wire-screw connector on each snipped end, and put a screw or bolt through BOTH and fasten them to the ground point. The circuit is still complete, but includes a ground separate from the battery, which imho is always a smart idea.
Edited by man on the moon, 08 April 2013 - 01:57 PM.
Posted 08 April 2013 - 01:59 PM
the way i mentioned runs the power throught the stock wiring so everything is fused and wired correctly using the stock realy and the fan will not turn on with the key off. its the easiest and best way, no need for heavy switches or extra wires.
this is how the fan on my 80 is running, i've never had a problem. the thermo switch on the radiator is just the ground to the relay that when it heats up creates a connection to ground. an even simpler way to do this would be to run a splice off of the negative on the coil side of the fan realy to a switch in the dash and back to chassis ground no need to run any wires through the fire wall and any switch will work since it is a very small draw.
Edited by mikaleda, 08 April 2013 - 02:05 PM.
Posted 08 April 2013 - 02:11 PM
The thermoswitch plugs into the radiator. Follow the pigtail from the fan, past the connector, and it will lead you to the switch where it is screwed into the radiator tank. It is separate from the temp sensor the ECU reads to determine engine temp. As to the temp sensor on the engine, I don't recommend cutting THAT temperature sensor, the car may not start...or won't run properly. Regardless, either method should work beautifully for you, and neither is even enough labor to get your hands greasy, and can be done in an hour for under $20 (and probably for free if you poke around in enough spare/rubbish/recycle bins).
Edited by man on the moon, 08 April 2013 - 02:15 PM.
Posted 08 April 2013 - 02:57 PM
Posted 08 April 2013 - 04:12 PM
If the working with the fan dosnt work...... You prolly have other problems you need to attend to. Radiator, thurmastat, waterpump... ect ect..
Posted 08 April 2013 - 04:56 PM
Posted 08 April 2013 - 06:45 PM
There are a lot of reasons why a car could overheat, but that debate is a red herring in regards to the OP.
The question is "The electric (backup/secondary/whatever) fan isn't turning on when it is supposed to. How can I get it to turn on when it needs to be on, rather than too late?".
The overheating question is a good one, and it needs to be addressed, but this thread will run away if we try to go after two questions--if we want to diagnose WHY it's getting hot, let's start another thread, or at least make sure the first question is closed in the OP's mind.
Posted 08 April 2013 - 06:47 PM
Oh never mind, I misread your post Prwa101. I thought you were telling the OP he was chasing the wrong problem. I apologize for potentially confusing you.
Posted 08 April 2013 - 11:25 PM
Just a thought too, are you running the electric fan and the one that hooks to the water pump?
How's the fan going?
Posted 09 April 2013 - 05:38 AM
When under full load (when coping with turbulent air, for example) the fan might be pulling quite a few amps so either have a switch rated to take the current (say, over 10 amps and possibly 20 or more) or fit a relay. I did the latter so only needed thin wire to and from a cheap switch and short lengths of thick wire between the fan and relay with an in-line fuse. I think I fitted a 30 amp relay and 20 amp fuse. Live feed came from the original fan feed. If you don't use a relay, the wire and switch must be rated for the fan or you could start an electrical fire. By the way, my solution was precautionary because I did not have an ampmeter handy when I needed to bypass the thermoswitch. The relay was only £2.50 so it's a cheap fix. If you have a meter handy, check the current being pulled under load - it might be lower than I think and you can ignore this post. :-) (though a relay is better!)
Posted 13 April 2013 - 01:54 PM
Posted 14 April 2013 - 11:42 AM
Posted 14 April 2013 - 01:05 PM
You're Welcome! ... That link also shows a Slightly Cooler Temps ThermoSwitch, in case you use Twin Electric Fans.
Posted 15 April 2013 - 08:11 AM
Posted 15 April 2013 - 10:35 AM
There's something abnormal here:
You wrote that even with the Mechanic Fan and the Electric Fan working together, plus the Heather blasting, the engine's temps where around 3/4! ... ... That is Overheating for Sure.
So, Beside that your Subie's Radiator must be Clogged (and / or your Thermostat could be Stuck somehow), I Imagine that you Reverse-Wired the Fan, because in the above post, you descibe an even Worse escenario than before in the First post of this thread, where your Subie didn't had a Working electric Fan.
Remember: Fans placed Behind the Radiator must PULL (Suck) Air from the front of the Car to the engine bay. That guarantees an Air Flow thru the Radiator when the car is moving, but if you Reverse-Wired it, the fan must be PUSHING (Blowing) Air to the front of the Car, which leads to have an air "Cushion" without air flowing thru the Radiator.
So, I Kindly Suggest you to check the Electric Fan's Air flow direction and give us Feedback.
Also, you might consider a chemical flush for the Radiator, you know: a Replacement from a Junk Yard could be as Clogged as the used one you removed from the car... and if your subie still runs with a Single-Row Radiator, you shall consider to Swap a Double-Row Radiator there, your Subies' Head Gaskets will be Thankful ... ...
Edited by Loyale 2.7 Turbo, 15 April 2013 - 10:36 AM.
Posted 15 April 2013 - 11:22 AM
Posted 15 April 2013 - 02:13 PM
Overheating can also be caused by a dried out radiator cap seal. It's worth the $5 to replace the cap. If you're losing fluid over time, there may be a leak, but I'd recommend a new cap in addition to the flush/clean suggested in bright blue above.
Posted 15 April 2013 - 05:17 PM
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