I ran the quad in the driveway for a bit to get it warmed up, fan never came on.
Rode it around the block a couple of times, quad getting hot, no fan.
Revved in driveway a little more, HOT light came on, no fan.
Turned key off, then back on, fan came on.

If the thermal fuse was bad, woouldn't that prevent the fan from coming on at all?
Seems like this is pointing towards a bad temp sensor more than wiring/fuse.

 

Spin the fan and make sure there are no bad spots in the rotation. Should feel smooth throughout the spin. If smooth I would replace the sensor.

 

Go to the members section and find my name badazzpred and go to my statistics and then to my started threads and you will find a whole lot of info on this problem as this happened to a buddy of mines we replaced the temp sensor, the filler neck, thermostat, tons of parts and we finally gave up and he took it in to the dealer and it was the fuse thats supposed to be sealed in that plastic bag lookin thing. Look for that it is located upfront and center like between the handlebars and radiator I will put my money on it that its all coroded inside there then again I could be wrong its worth a try. otherwise be sure to keep us posted as to what ur problem was................

 

I'm going to try replacing the temerature sensor next. The repair manual (if you want to call it that) calls it a "thermister". Looks to me like it's this spark-plug looking thing screwed into the left side of the motor just below where the coolant return hose connects.

It has what I can only assume is some sort of sealant on the threads. You can just barely see a red colored coating on the last couple of threads.

Question: what is this, where do I get some, how do I apply it?

Also, the service department at my local dealer quoted me $59 on the Thermister. Anybody know where I can get one cheaper than that?

 

On the sensor on the engine just use teflon tape.Be sure to tighten sensor first and not plug into harness and let the wires turn with sensor as you snug down or wiring will become twisted and you could damage wiring!Very easy job and if you're quick enough,very little coolant loss. Its my guess that it is not the problem,BUT have been wrong before! I had to replace some Chinese ecms that weren't on the recall on 2006 machines! Especially if fan erratic. Ecm main function controls the fan operation and charging.
Good luck,keep us updated!! OPT

 

im having this problem, temp light comes on but i have a guage on it says its not running hot, but the fan doesnt come on then it runs hot. so maybe I have a bad fan but why is the light coming on when it not hot?

 

Just put 12 volts to the fan motor first to see if it's ok. You didn't say what year model you have?? Could be a radiator sensor,thermal sensor on the cylinder,ecm module if it's a carb model,etc. Be a little more specific as to what year and model you have. OPT

 

mines a 06 sportsman 500, dealer done replaced the ecm on recall.

 

If the fan motor is ok(you can put 12 volts directly to it),radiator is clean and you've made sure you've bleed the cooling system of any air pockets, but machine is getting hot and the fan isn't coming on you could have another bad ecm module! I replaced several of the "updated" American made Surepower modules along with the crappy Chinese originals. Some machines I replaced multiple ecms on the same machines as well as several members on the forum have done the same.Plus it could just be the thermal sensor on the left side of the cylinder faulty,triggering the hot light.You can check the resistance on the sensor when it's cold,then check it when it's hot and see if the resistance numbers drop. But if the fan never cycles on and off it is the ecm module that controls it. OPT

 

finally got my new fan on, everything works fine now, so I take it if the fan doesnt work at all the engine hot light flashes? it not flashing hot anymore. BTW I got my fan from DB Performance, Inc. for 52.95 but you have to swap the motor from there housing to yours.