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help! electric fan won't come on!


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18 replies to this topic

#1 bratgirl

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Posted 23 September 2004 - 01:37 PM

Hey Guys:

I've got an 84 Brat ea81 with an electric cooling fan that won't behave. It used to come on most of the time (I mean, when it got hot enough), but now it won't come on at all - in a month it won't matter, but it's still 90 degrees down here. I've replaced the fan motor (and tested it to make sure it works) - still no go. This morning I replaced the thermocoupler - again no go. There is no A/C in my Brat, so I'm confused by the relay diagram in my Haynes. By that black cannister thingy, there is a whole bunch of plugs hooked up to nothing, and then one round relay (maybe?) hooked up. Anyway, I've got no idea where to go from here. Any input is appreciated!!!

Thanks!!!
Bratgirl

#2 archemitis

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Posted 23 September 2004 - 01:52 PM

my girlfriends hatch did the same thing. i just took the power, ran it to a switch inside the cab, and told her to watch the guage.

i thought it was just power going through the thermoswitch, and power goin to the fan, no relay or anything to deal with.

and usually it is the thermoswitch, you can check that with meter, at normal temp it shouldnt have any continuity, and at about 210 degrees it should close.

#3 cole098

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Posted 23 September 2004 - 02:09 PM

I had a similar problem... If you have a new thermoswitch try taking it out and boiling it in a pot of water... There should be no continuity with a multimeter when the switch is cold.. When hot you should have continuity thus your Ohm meter will go to zero or if you have a digital meter with a continuity checker it should beep...

#4 ronnie johhhnnn

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Posted 23 September 2004 - 04:36 PM

This may be a dumb answer but it is something that I always overlook. Check the fuse.

#5 bratgirl

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Posted 23 September 2004 - 05:08 PM

This may be a dumb answer but it is something that I always overlook. Check the fuse.

Thanks for the suggestion, but that was 1st thing checked. Also, ground wires for the fan are in good shape (it comes on when "jump wired" to battery.

#6 Flow

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Posted 23 September 2004 - 05:46 PM

If you pull the yellow wire off of the thermoswitch on the radiator and ground it, does the fan come on?



Thanks for the suggestion, but that was 1st thing checked. Also, ground wires for the fan are in good shape (it comes on when "jump wired" to battery.



#7 bratgirl

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Posted 23 September 2004 - 06:15 PM

If you pull the yellow wire off of the thermoswitch on the radiator and ground it, does the fan come on?

Do you mean after it gets up to temperature? I'll give it try & let you know. If it doesn't, what does that mean? If it does, what does that mean?

#8 Cougar

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Posted 24 September 2004 - 01:33 AM

By touching the yellow wire to ground I think Flow was trying to test the fan circuit. By grounding the wire and having the fan turn on , this would prove the wiring and power to the fan is ok, and the themoswitch is bad.

#9 edrach

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Posted 24 September 2004 - 02:48 AM

There should be a small black wire at the top center of the radiator which grounds the radiator to the chassis. If it's not there or broken, the radiator is not grounded and the the fan will not work. Flow's suggestion is spot on. If you touch the yellow wire to a good ground the fan should come on (doesn't matter if the engine is hot or cold--it should work either way since you're by-passing the thermal switch); if it does, you know the fan is getting power and the fan motor is good; then you have either a bad thermal switch or poorly grounded radiator. If the fan doesn't come when you touch the yellow wire to a good ground, you either have no power to the fan or a bad fan motor.

#10 Seahag1978

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Posted 24 September 2004 - 06:52 AM

my girlfriends hatch did the same thing. i just took the power, ran it to a switch inside the cab, and told her to watch the guage.

i thought it was just power going through the thermoswitch, and power goin to the fan, no relay or anything to deal with.

and usually it is the thermoswitch, you can check that with meter, at normal temp it shouldnt have any continuity, and at about 210 degrees it should close.


My 78 Brat has this switch installed, and my temperature guage doesn't move...it's one thing I started to deal with... but everything else fell apart, and this problem slipped down the list... All this information is great and will be needed, once the major problems are fixed and I can actually drive long enough to get the engine hot?!
Thanks!

#11 edrach

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Posted 24 September 2004 - 09:38 AM

Mary, don't confuse the thermoSWITCH on the radiator which turns on the fan with the thermal SENSOR which tells the temp guage what the water temp is in the engine. Two different items with two different, but related, functions.

My 78 Brat has this switch installed, and my temperature guage doesn't move...it's one thing I started to deal with... but everything else fell apart, and this problem slipped down the list... All this information is great and will be needed, once the major problems are fixed and I can actually drive long enough to get the engine hot?! Thanks!



#12 subiemech85

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Posted 24 September 2004 - 11:59 AM

and if it is a feedback carb, the "sending unit" has two, 2, connectors

#13 bratgirl

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Posted 24 September 2004 - 12:15 PM

There should be a small black wire at the top center of the radiator which grounds the radiator to the chassis. If it's not there or broken, the radiator is not grounded and the the fan will not work. Flow's suggestion is spot on. If you touch the yellow wire to a good ground the fan should come on (doesn't matter if the engine is hot or cold--it should work either way since you're by-passing the thermal switch); if it does, you know the fan is getting power and the fan motor is good; then you have either a bad thermal switch or poorly grounded radiator. If the fan doesn't come when you touch the yellow wire to a good ground, you either have no power to the fan or a bad fan motor.

I think I've got a bad wire somewhere. We've already made sure the fan motor works (you can also test this by hooking up the "jump wires" that came on our meter to the battery and hook it direct to the fan motor electrical plug). Also, made sure that the ground wires are good. Also, made sure the fuse is good. Also, replaced the thermoswitch. What else can I Do? The fan used to work, and now it's being a bad, bad, girl. I think I might put a switch on the dash to operate, I'm getting so frustrated.:banghead:

#14 Flow

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Posted 24 September 2004 - 01:01 PM

I think I've got a bad wire somewhere. We've already made sure the fan motor works (you can also test this by hooking up the "jump wires" that came on our meter to the battery and hook it direct to the fan motor electrical plug). Also, made sure that the ground wires are good. Also, made sure the fuse is good. Also, replaced the thermoswitch. What else can I Do? The fan used to work, and now it's being a bad, bad, girl. I think I might put a switch on the dash to operate, I'm getting so frustrated.:banghead:

So the fan did not run when you grounded the yellow wire? If it didn't, your grounds and fuses are ok, and the thermoswitch is new then I would suspect the relay.
'83 FSM says its behind the pass. side strut tower. I can't double check that on my car right now tho. I would pull a Junk yard relay and swap it out and see what happens. Hope this helps, Good Luck!

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#15 Seahag1978

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Posted 24 September 2004 - 03:11 PM

I think I've got a bad wire somewhere. We've already made sure the fan motor works (you can also test this by hooking up the "jump wires" that came on our meter to the battery and hook it direct to the fan motor electrical plug). Also, made sure that the ground wires are good. Also, made sure the fuse is good. Also, replaced the thermoswitch. What else can I Do? The fan used to work, and now it's being a bad, bad, girl. I think I might put a switch on the dash to operate, I'm getting so frustrated.:banghead:


I'm not sure if I was very clear in my earlier reply... I do have a switch installed on the dash to operate the fan manually... someone must have gotten frustrated and installed it instead of tracking down the problem. My temperature guage doesn't move to warn me of overheating. I just know I'll forget to turn the fan on and fry my engine... yikes!

#16 Flow

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Posted 24 September 2004 - 03:52 PM

I'm not sure if I was very clear in my earlier reply... I do have a switch installed on the dash to operate the fan manually... someone must have gotten frustrated and installed it instead of tracking down the problem. My temperature guage doesn't move to warn me of overheating. I just know I'll forget to turn the fan on and fry my engine... yikes!


In your case you will want to investigate the thermosensor located in the manifold. You might also want to start a seperate thread if you have furthur problems. As Edrach said, your problem is somewhat related but is confusing to Bratgirls seperate issue. Good luck!:)

#17 bratgirl

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Posted 24 September 2004 - 05:44 PM

So the fan did not run when you grounded the yellow wire? If it didn't, your grounds and fuses are ok, and the thermoswitch is new then I would suspect the relay.
'83 FSM says its behind the pass. side strut tower. I can't double check that on my car right now tho. I would pull a Junk yard relay and swap it out and see what happens. Hope this helps, Good Luck!

I haven't had a chance to try the yellow wire trick yet, probably won't until after the weekend (going camping, sadly w/o the brat until I fix this). Does my Brat have a relay for the fan? It didn't come with A/C, so therefore it has only one fan, and my boyfriend and I looked & looked for a relay and couldn't find it.

P.S. - thanks for all the help Subie Masters!

#18 sub4b4

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Posted 24 September 2004 - 06:36 PM

use a test light, an trace it {power} back as far as you can. also look for wires for rubbing the body,if anything is in the way remove it. if you have to rewire to the fuse box.

#19 zstalker

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Posted 19 April 2007 - 03:14 PM

sorry to dig up an old thread, but I've got the same issue (fan not coming on, coolant getting very hot). I've ben searching the forum, top to bottom, and still have a question. My 1984 Brat does not have air conditioning, so only one fan. I looked in Alldata, the facoty service manual, and a Haynes manual, and they all agree that the main cooling fan is controlled by a relay that is situated by the ignition coil...but by my ignition coil, I've got a fusible link box, and a bundle of connectors all tied off and not used (A/C connectors, I'm guessing), but NO RELAYS. Looked under the dash with the fuses, no relays.
So from what I'm reading here, am I to believe that on certain cars the thermoswitch in the radiator takes the full brunt of the cooling fan power when it switches closed, with no relays involved? if so, I'm going to put in a new thermoswitch (already ordered), and hook it through a relay to protect it from here on out. I manually grounded the wire going to the switch, and sure enough, the fan came on, so I'm just finding any more weak points in the system. oh, also I'm going to very well ground the radiator body as well, since it needs that path.
thanks for your responces in advance
~Erik~




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