When should the clutch fan lock up/unlock??
11-11-2007, 10:17 AM
#16
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As Spooler has pointed out...as per the manual the clutch is variable...it doesn't necessarily fully lock or unlock but trys to keep a target speed determined by the sensors. It is possible that there is more damage to your system than you thought or it may be working normally. Either way the only real test is to use the manual and a scantool.
Good luck and let us know if you find anything abnormal.
Good luck and let us know if you find anything abnormal.
11-11-2007, 10:26 AM
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Also there was supposed to be a fan speed reference chart after step 12 in the manual...for some reason it didn't show up when I pasted it...basically fan speed is slightly lower then engine RPM during the test in step 12.
11-11-2007, 04:21 PM
#18
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The fan clutch is controled by the ECM. At idle with the A/C on and up to operating temperature the fan will cycle engaging the clutch on and off. It never fully locks. I think there is a thermister in the assembly telling the ECM what temps it sees by varying the voltage. The ECM then interprets when and how to cut on the clutch. Your fan should lock/unlock at idle and completely cut off after you start moving down the road with the A/C on. It seems as though yours got damaged when the wires were ripped out and needs to be replaced. That clutch isn't cheap either. Different year models are programed differently. The new trucks will keep the clutch on longer due to the problem everyone was having with the different temps coming out the vents from left to right. Beemo talked about this in the big A/C thread and I am sure that he had something to do with the programing change in the newer 07' trucks. With that fan on alot I bet it sure sucks down some fuel.
That makes alot of sense, and I believe you are right...my clutch is damaged (or teh electrical portion of it) as teh clutch is locked FULLY at all times.....idle, driving down the road...it NEVER disengages (sp??)
11-11-2007, 04:23 PM
#19
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What I described to you IS how my fan works but it also the text book way it should work as well. The reason yours may not have worked like this before is your wires may have been damaged for a long time...just not "ripped out" until you noticed them as so.
By cutting the wire there is still a good chance it will run ok but that is partially because there is air flow over the rad and AC condenser while driving...just sometimes not enough under certain conditions which is why the fan clutch will engage with AC or when ECM commands it due to ECT temp. What are the ambient temps outside while you did the 'cut the wire' test? I assume lower then say being in Arizona during July?
I still say there is nothing wrong with the current operation of your fan clutch and it is now working as designed. If it did not work this way before I would say you had a problem before then....but it may be wise to check operation by the service manual incase I am wrong.
The link for how a fan clutch works is wrong for our trucks. It is how an older style viscous fan clutch works. Ours are electronically activated and work more reliably as well as more consistently for given conditions.
By cutting the wire there is still a good chance it will run ok but that is partially because there is air flow over the rad and AC condenser while driving...just sometimes not enough under certain conditions which is why the fan clutch will engage with AC or when ECM commands it due to ECT temp. What are the ambient temps outside while you did the 'cut the wire' test? I assume lower then say being in Arizona during July?
I still say there is nothing wrong with the current operation of your fan clutch and it is now working as designed. If it did not work this way before I would say you had a problem before then....but it may be wise to check operation by the service manual incase I am wrong.
The link for how a fan clutch works is wrong for our trucks. It is how an older style viscous fan clutch works. Ours are electronically activated and work more reliably as well as more consistently for given conditions.
Oh, ok. I was not sure if you were referring to your truck, or just how it was supposed to be. Thanks for this info you have shared!
11-11-2007, 04:24 PM
#20
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11-11-2007, 04:26 PM
#21
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As Spooler has pointed out...as per the manual the clutch is variable...it doesn't necessarily fully lock or unlock but trys to keep a target speed determined by the sensors. It is possible that there is more damage to your system than you thought or it may be working normally. Either way the only real test is to use the manual and a scantool.
Good luck and let us know if you find anything abnormal.
Good luck and let us know if you find anything abnormal.
OK, again, thanks! Mine currently is not variable, it is locked up, and I would say it is locked up FULLY, as this thing is moving some serious air. I might as well have a 6" stack inside my cab it is so loud
11-11-2007, 04:33 PM
#22
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OK, and back to my test I was performing.......nope did not work. I put @ 17 miles on teh truck this morning, and it was fine. This afternoon, I put about 25 miles on it, and the AC finally quit working @ idle. What happens is teh ECM shuts the AC compressor off when I come to a stop/idle. Once I get going teh ECM turns teh comprssor back on, as it probaly sense's wheel speed, engine RPM, etc....kind of like a safety feature built in....when it sense's movement/speed, it feels it is OK to turn compressor back on as it knows there is airflow over the condensor, and at idle (0 MPH), no airflow, so it shuts compressor off. So,I need to splice the blue wire back, and try something else. I will keep updates coming, as I know this is something that is not talked about alot around here, so, I feel a learning curve is needed because as mileage racks up on our trucks, it is likely we could start seeing more of these problems, and would be nice to know that there is an answer to this problem.
11-11-2007, 09:48 PM
#24
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What actually happen with your A/C is the high side got to high, kicked the high side switch on and turned off your compressor. This is to keep from blowing everything to smitherians so to speak. Just so you know that pressure is around 500-550 PSI and that could be a component killer for the A/C system so be careful.
11-12-2007, 07:44 AM
#25
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ONLY if I turn off the AC will the clutch disengage. When I first got teh wires hooked back up, it did it ALL the time, even with teh AC off. Then, I guess, as teh ECM "relearned" it then would shut the clutch with the AC off, and THEN it seemed to act OK....it would lock and unlock as I was driving it (AC on) and I just thought, OK, ECM is learning and everything will be OK. Well, then, it went back to lock up 100% of the time with AC on, and has been since.
11-12-2007, 07:58 AM
#26
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What actually happen with your A/C is the high side got to high, kicked the high side switch on and turned off your compressor. This is to keep from blowing everything to smitherians so to speak. Just so you know that pressure is around 500-550 PSI and that could be a component killer for the A/C system so be careful.
WEll, your theory sounds like that is what SHOULD have happened, but is not. I am an ASE tech, and I have gauges.....pressure readings are fine. @ 35-40 lbs on teh low side and @ 235-245 LBS on teh high side (ambient temp @ 75-79*). So, teh condensor is NOT getting hot and causing elevated temps (AC or coolant), and no reason for compressor to be shut off. IN fact, sometimes it will do it after I JUST start the truck up (AC won't work @ idle). I have been down this path, I KNOW it is in the wiring. As if I plug everything back up, AC will work, 100% of the time, period. Take right now, my truck has sat overnight, I can unplug the fan, start my truck up, and AC will NOT work @ idle. If I plug the fan back in, it will. Period. Again, your theory is what SHOULD happen, but is not. Thanks for your effort though!
Well, I am going to cut the fan speed wire today (pole position #3, orange wire) as I cut the fused ign. switch output run yesterday (pole position #6, dark blue wire) and see if THAT works. I am going to cut ALL 5 wires eventually if I have to, to eliminate that as a possible solution to my problem.
I do have a question for you guys (since my harness was ripped to shreads). The harness starts at the fan, and runs down the radiator over to the PS of teh truck, and then plugs into a harness. From teh fan to that plug, is about 18" or so. My harness from teh fan, only had about 4" on it. Is there ANOTHER plug that may have gotten ripped out that I do not know of? Is there anyone near the Pearland area so I can take a look at your truck/harness????
11-12-2007, 01:49 PM
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ONLY if I turn off the AC will the clutch disengage. When I first got teh wires hooked back up, it did it ALL the time, even with teh AC off. Then, I guess, as teh ECM "relearned" it then would shut the clutch with the AC off, and THEN it seemed to act OK....it would lock and unlock as I was driving it (AC on) and I just thought, OK, ECM is learning and everything will be OK. Well, then, it went back to lock up 100% of the time with AC on, and has been since.
Sorry, I kind of hopped through this string..... Does your A/C cut out if you stomp on it, as if pulling a hill, accelerating to pass, or the like? Up here in the Great White North I haven't had occasion to us the cold side of the dial for a while but over the summer mine would cut out during acceleration. It also seemed to always be on at idle. This is my first Dodge and therefore I am new to their systems. Is this A/C compressor a variable displacement system?
As for your clutch fan......What ever happened to the simple and relatively easy thermostatically controlled fan? Start it up and the fan roared to life. As it warmed up, the clutch relaxed and the blades freewheeled. Radiator gets warm and warms the clutch and the fan would roar back to life. Must have been too simple. The only time I was aware my fan was operating was in the heat in stop and go traffic or (believe it or not) at speed; 75+ on the E-way with the A/C running. This last part I find just dumb as I would hope that the force of 75+ mph air would be enough to push through the A/C condensor, intercooler, and radiator. Maybe they have too much ssssshhhhhhtuff in front of the radiator?
11-12-2007, 02:47 PM
#28
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Sorry, I kind of hopped through this string..... Does your A/C cut out if you stomp on it, as if pulling a hill, accelerating to pass, or the like? Up here in the Great White North I haven't had occasion to us the cold side of the dial for a while but over the summer mine would cut out during acceleration. It also seemed to always be on at idle. This is my first Dodge and therefore I am new to their systems. Is this A/C compressor a variable displacement system?
As for your clutch fan......What ever happened to the simple and relatively easy thermostatically controlled fan? Start it up and the fan roared to life. As it warmed up, the clutch relaxed and the blades freewheeled. Radiator gets warm and warms the clutch and the fan would roar back to life. Must have been too simple. The only time I was aware my fan was operating was in the heat in stop and go traffic or (believe it or not) at speed; 75+ on the E-way with the A/C running. This last part I find just dumb as I would hope that the force of 75+ mph air would be enough to push through the A/C condensor, intercooler, and radiator. Maybe they have too much ssssshhhhhhtuff in front of the radiator?
As for your clutch fan......What ever happened to the simple and relatively easy thermostatically controlled fan? Start it up and the fan roared to life. As it warmed up, the clutch relaxed and the blades freewheeled. Radiator gets warm and warms the clutch and the fan would roar back to life. Must have been too simple. The only time I was aware my fan was operating was in the heat in stop and go traffic or (believe it or not) at speed; 75+ on the E-way with the A/C running. This last part I find just dumb as I would hope that the force of 75+ mph air would be enough to push through the A/C condensor, intercooler, and radiator. Maybe they have too much ssssshhhhhhtuff in front of the radiator?
No, AC works great at all times (except @ idle with the fan plugged in).
Yeah, it would make sense about the ol skool approach with the fan, and now that I am having these problems, even more so!
11-12-2007, 03:41 PM
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had my son check his 03 and the wires at the plug match color for color but no red wire and according to the 03 digram there is no red wire either.
just notice your engine and checked my 04 diagram and pin 6-grey/pink (ignition switch)wire and a pin 5-yel/pink( 5 volt supply) wire. pin 2-dark blue/dark green (ground), pin 1-brown/orange (lockout solenoid), pin 3-brown/light blue(fan speed) fan part # 52028879AF
just notice your engine and checked my 04 diagram and pin 6-grey/pink (ignition switch)wire and a pin 5-yel/pink( 5 volt supply) wire. pin 2-dark blue/dark green (ground), pin 1-brown/orange (lockout solenoid), pin 3-brown/light blue(fan speed) fan part # 52028879AF
11-12-2007, 04:23 PM
#30
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had my son check his 03 and the wires at the plug match color for color but no red wire and according to the 03 digram there is no red wire either. as for the blue wire(dark blue igntion switch ouput) that is not a wire, i think the copper got pulled out on it. Is there two parts numbers for the fan on your truck? because there is for mine. just my 0.0002cdn info help.
OK, thanks for your help! Right, AT THE PLUG, there are only 5 wires, and they match color for color. But my harness got ripped out only about 4-5" from the back side of the fan, and inside that loom is where the 6 wires are. I am just curious where that red wire goes. And, as you said, the diagram according to the service manual mentions nothing of a red wire, and of course that is what does not make any sense either. I would think you would be riht about the blue wire and the copper strandsbeing pulled out, except for this: teh insualtion. Why is there insualtion inside the blue wire, and no other wires? And one other thing, the harness got cut like someone took a cutter too it, a very clean cut. Not frayed like you would think. At this point however, none of it really makes any sense, and I am officially guessing at this point. I think what I may do is go down to te dealer, and talk to a tech, and maybe ask to see one of their clutches and or show them mine, and see what they think.
Guys, I really appreciate all of your help on this, the info you have shared in trying to get this figured out. I am NOT admitting defeat, as I will continue to do battle until I get this problem resolved, and at that time, I will post results on the outcome for all of us to be able to share in teh knowledge gained by this ordeal.