JerryB Posted April 27, 2009 Share Posted April 27, 2009 Gentlemen. My 2004 Vision w460 has a viscose cooling fan that stays engaged at all times. The error code flashes for "FAN RELAY" but I can't find the fan relay all I can find is a 15amp fuse in the engine compartment firewall box. The 15amp fuse is not blown so can someone please tell me where the fan relay is located??It is not a Horton air activated type fan clutch it only has 5 electrical wires going to the clutch hub. I have checked all 5 wires in the clutch hub harness and all are good with no corrosion or breaks. Any help is greatly appreciated--Thanks-Jerry Quote Link to comment https://www.bigmacktrucks.com/topic/9183-fan-relay/ Share on other sites More sharing options...
Mackpro Posted April 27, 2009 Share Posted April 27, 2009 Gentlemen. My 2004 Vision w460 has a viscose cooling fan that stays engaged at all times. The error code flashes for "FAN RELAY" but I can't find the fan relay all I can find is a 15amp fuse in the engine compartment firewall box. The 15amp fuse is not blown so can someone please tell me where the fan relay is located??It is not a Horton air activated type fan clutch it only has 5 electrical wires going to the clutch hub. I have checked all 5 wires in the clutch hub harness and all are good with no corrosion or breaks. Any help is greatly appreciated--Thanks-JerryThe fan clutch you have is the Behr electric viscous fan clutch, made in germany. Unlike the air fan clutches, it never really totaly "freewheels", its always turning. With the engine off and key off, grab the fan blade and try to turn it, if its so "locked up" that it slips the belts or you cant turn it, it's bad and you need a new fan clutch. When you start it up, the fan should be engaged and roaring for around 10 minutes at 1100-1500 rpm then slowly the roaring will get softer and softer and the fan will disengage, this is normal. I have seen the AC high side pressure switch and wiring be bad and cause the fan to stay engaged. I dont belive there is a "fan relay'" all the wires come from the engine ECU. Quote Link to comment https://www.bigmacktrucks.com/topic/9183-fan-relay/#findComment-34447 Share on other sites More sharing options...
Mackpro Posted April 27, 2009 Share Posted April 27, 2009 Heres the wirig to the fan clutch Quote Link to comment https://www.bigmacktrucks.com/topic/9183-fan-relay/#findComment-34448 Share on other sites More sharing options...
JerryB Posted April 29, 2009 Author Share Posted April 29, 2009 Thanks Mackpro. We checked the fan clutch and it checked good so then I had the wiring checked, the connections checked, also checked the ac pressure switches and temp sending units and they checked good. The fan still runs continuous so we're still checking. Thanks for your help Quote Link to comment https://www.bigmacktrucks.com/topic/9183-fan-relay/#findComment-34493 Share on other sites More sharing options...
tylerstanley Posted April 29, 2009 Share Posted April 29, 2009 My Fan was stuck on because of too much pressure in the AC system. The fan would come on to try and get the head pressure down, but it would just stay on. To see if thats the problem, start the truck with the AC button in the cab OFF, then see if your fan kicks on or off? I know my fan will run until the air tank has built up, but i think that is because its a air operated clutch.... But either way, check that...... So you know thats not to problem...... OR you can turn off the switch and wait about 5 minutes, then my fan would shut off then. Either way. Quote Link to comment https://www.bigmacktrucks.com/topic/9183-fan-relay/#findComment-34494 Share on other sites More sharing options...
DavidT Posted May 8, 2009 Share Posted May 8, 2009 My Fan was stuck on because of too much pressure in the AC system. The fan would come on to try and get the head pressure down, but it would just stay on. To see if thats the problem, start the truck with the AC button in the cab OFF, then see if your fan kicks on or off? I know my fan will run until the air tank has built up, but i think that is because its a air operated clutch.... But either way, check that...... So you know thats not to problem...... OR you can turn off the switch and wait about 5 minutes, then my fan would shut off then. Either way.I have had two this season so far that had excessive AC head pressure even with the system turned off. This was due to a faulty expansion valve. That was the original complaint, the engine fan stays on all the time. Another way to rule out a clutch that has mechanically failed is to bring the engine RPM over 1900. After a few seconds you should hear it fade out regardless of AC head pressure or coolant temperature unless it has mechanically failed. Quote Link to comment https://www.bigmacktrucks.com/topic/9183-fan-relay/#findComment-34914 Share on other sites More sharing options...
davekt Posted May 10, 2009 Share Posted May 10, 2009 On the EGR Mixer pipe above the intake mainfold there are 2 sensors, one is onstalled vertically and the other one is somewhat horizontal, it is the same part number as the intake manifold temperature sensor, try plugging in a new sensor without installing it. There is no diagnostics or fault code for this sensor and usually the only way to know if it is bad is the engine fan stays engaged all the time. Quote Link to comment https://www.bigmacktrucks.com/topic/9183-fan-relay/#findComment-35019 Share on other sites More sharing options...
davekt Posted May 10, 2009 Share Posted May 10, 2009 On the EGR Mixer pipe above the intake mainfold there are 2 sensors, one is installed vertically and the other one is somewhat horizontal, the horizontal one is the one to check. It is the same part number as the intake manifold temperature sensor, try plugging in a new sensor without installing it. There is no diagnostics or fault code for this sensor and usually the only way to know if it is bad is the engine fan stays engaged all the time. Quote Link to comment https://www.bigmacktrucks.com/topic/9183-fan-relay/#findComment-35020 Share on other sites More sharing options...
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