An friend has an 2004 400 sportsman thats running hot..Changed thermostat no change..ran without thermostat still runs hot,changed the thermo switch in head no change, meter flashing hot code...water is cirulating ok. used an temp laser gun on it today 195 degress to 205 degress still fan not coming on..did put power to fan an it works n cools perfect, but fan wont come by itself..put an volt meter at fan harness conector an read 14 volt hot and 12 volt cooled off.. Im alittle confused..have power to fan from harness but wont work..but can put power to fan from batt an fan works fine an cools off great..We ran an batt ground to fan harness but no change.Thanks in advance

 

First check the 10 amp sealed circuit breaker under the front panel up by the cdi area. Must have power on the red wires on each side of the pouch. If it's bad,you can get it any any auto store for a few bucks.Most of the time though it's a shorted out radiator sensor that doesn't allow the fan to come on. It provides the ground path for the fan circuit. Item #21.Dirt Cheap Yamaha, Polaris, Suzuki & Kawasaki OEM Parts & Accessories – Cycle Parts Warehouse You can substitute this high $ sensor with a Wells Sw526 temp sensor at most auto stores,Autozone,Advance Auto,Napa,etc.. Just cut your oem connector end and reuse it on the new sensor.Be sure to raise the front end and leave the radiator cap off after repairing and filled with coolant to remove any trapped air or it can over heat again even if the fan is working.Just let the fan cycle on and off a few times and you'll see the coolant level drop. Top off the radiator,replace the cap and top off the over flow bottle.

 

Thanks OPT for your reply...If you notice there are 2 400 sportsman on parts fiche.The model we have doesnt have sensor in radiator the item 21 as you mention... the below link is the model we have..I do have an breaker or sensor that screw into the firewall.. has 2 pin.. 2 red wires on one side and orange on the other side..But cannot find or know what this. I have 12 volts on one side of it low volts on the other side.

 

2004 Polaris A04CH42AQ SPORTSMAN 400 (A04CH42AQ/AR/AS/AT/AV) Cooling System | Ronnie's Mail Order

 

Welp,since you have the AQ model,the ecm module controls just about everything. From containing all the circuit breakers,battery protection circuit,charging and also fan operation.Sounds like another one has bit the dust. If you still have the original one(4010397) it updates to the latest Sure Power 2203348 silver module. Shame it wasn't on the recall list like the 2005 models were.New Surepower ECM Kit Polaris 2203348 400 450 500 | eBay You might want to check connections,etc,but wouldn't hold my breath on this one. Common thing for even the newer ones to heat up and short out.