fan will not come on.... - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #1 of 44 (permalink) Old 04-11-2016, 02:20 PM Thread Starter
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fan will not come on....

so at the end of the summer last year, my fan switch kicked the bucket. my fan was staying on and running my battery down. when i went to inspect the situation the spade that the connector slide on to was so corroded, it crumbed in my hand when i tried to pull it off. i replaced the switch this past weekend with a switch i tested before i installed it. so now the damn fan will not come on at all. first i cant get it to turn off, now i cant get it to come on.

i am going to take the radiator off to look at the grounding wire, but that is the only thing i know to do. anyone else have thoughts or input as to what i should do or look at next?

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post #2 of 44 (permalink) Old 04-11-2016, 02:23 PM
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jumper a wire from the fan switch on the radiator, to a known good ground. fan should run, that verifies rest of circuit and fan.

if that fails, more troubleshooting needed, if it works, its either the fan switch, or the radiator isn't grounded properly.
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post #3 of 44 (permalink) Old 04-11-2016, 03:45 PM
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Blue wire on the 10-pin plug at the Junction Box, powers the fan. Spade connector on mine was loose and stopped the fan.

That wire should also be on one of the plugs under the neck covers. So check the connections there too.

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post #4 of 44 (permalink) Old 04-12-2016, 10:09 AM Thread Starter
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Great. thanks for the info guys. hopefully i will get a chance to check this out this weekend. i will give an update then.

Drew
'03 VN750 a little over 4300 miles
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post #5 of 44 (permalink) Old 04-12-2016, 08:57 PM
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The death of my temp sensor last year made for this handy little inconspicuous switch. I put it on for a week waiting on the new switch. When the switch came I left it on because sometimes in traffic I flip it earlier than the fan likes to come on and it stays cooler. Also, the fan switch sends a signal of varying potential so it isn't always wide open at lower temps. With the switch it's full tilt until I turn it off and I really have enjoyed having it. I consider it a useful addition.
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post #6 of 44 (permalink) Old 04-12-2016, 09:07 PM
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Quote:
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Also, the fan switch sends a signal of varying potential so it isn't always wide open at lower temps. .
if your talking the stock fan switch?? then its ON or OFF, not any variable output to it. All it does is feed a relay in the junction box to turn the fan on or off.

the temp gauge sender on the other hand (which is mounted in the thermostat housing, NOT the radiator) does have a variable resistance to allow the temp gauge to function.

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post #7 of 44 (permalink) Old 04-12-2016, 11:37 PM
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Quote:
Originally Posted by michiganteddybear View Post
if your talking the stock fan switch?? then its ON or OFF, not any variable output to it. All it does is feed a relay in the junction box to turn the fan on or off.

the temp gauge sender on the other hand (which is mounted in the thermostat housing, NOT the radiator) does have a variable resistance to allow the temp gauge to function.
Actually...

Quote:
Originally Posted by One1 View Post
the fan switch sends a signal of varying potential so it isn't always wide open at lower temps.
and because of that, it can cause pitting and eventual failure in the relay since... when its in the "sweet spot", it will bring the relay only down far enough to arc its secondary coil.

I'll try and cross-reference the part if you like, i had it earlier before my other computer died... had fan problems at the get-go.

It will ground on a curve of resistance, basically.
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post #8 of 44 (permalink) Old 04-13-2016, 09:14 AM
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no, the fan switch is a thermal switch.. open when cold, closed when hot

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post #9 of 44 (permalink) Old 04-13-2016, 12:33 PM Thread Starter
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all i know is that the fan switch, part# 27010, is what crumbled in my hand. it is located on the bottom left corner of the radiator. that is what i replaced. when i tested it, i clipped a multimeter to each end and put it in a pot of water on the stove. as the water started to boil the meter started beeping. when i pulled it out of the water, it stopped beeping. put it back in the water, it started beeping again. seems like it is just an expansion switch. once the metal is hot enough it expands to the point that a connection is made which completes the circuit. i wouldnt think there was to much more to it than that. but i dont know what the inside of that thing looks like so there could be some variable resistance stuff going on in there. as long as it works, i dont care.

i took the radiator off too because i had to get to the front exhaust manifold. so i am guessing it isnt grounded well. but it is good to know which wires to trace down. i was thinking about putting a toggle switch in but didnt really have a reason for it. this might might be that reason.

Drew
'03 VN750 a little over 4300 miles
Spline lube
F&S Rear blinker relocation
F&S Luggage rack
Saddlebags
F&S Extended backrest
Mustang seat
F&S Engine guard
Plexifairing 3 windshield
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post #10 of 44 (permalink) Old 04-13-2016, 01:39 PM
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ground the lead that connects to the fan switch. that will test the rest of the circuit. if the fan runs, the problem is the switch or radiator ground. if it dont run, more troubleshooting needs to be done to determine where the fault is.

yes, you are correct, the fan switch is a thermal switch, either on or off. there is not 'variable resistance' to it at all.

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