Anybody ever troubleshoot one of these?
I did the "rolled up newspaper" test (actually with a folded piece of cardboard), and with engine and oil fully warmed up I could stop the fan pretty easily - which sounds like a bad viscous coupling, but seems like a pretty vague test - how "hard" do these lock up with the viscous coupling? My recollection of my rx7 fan from like 10 years ago was near locked behavior of fan to engine speed.
I'm leaning towards just replacing it since it seems to fail the newspaper test, but curious what others have found.
The symptom that got me looking at the fan isn't engine overheat, it's warm A/C when at stop lights. Obviously, lots of potential causes of that symptom, but I am starting with proper airflow when idling. Aux fan works fine.
Car is a z3M coupe, but I think all the 6 cylinders of that era used the same fan.
Replace.
If it were me? I'd just replace it with an electric fan. Plenty of PnP kits available.
If the fan spins freely when you shut the engine down, it is dead.
when you start a cold engine the fan will idle, as the radiator warms you can see/hear the fan pick up speed.
I have a little used one off my KJ, anybody want it. Towing package came with two fans. Clutch and electric. Electric was more than adequate.
Yep, it's dead. Replace. BTW, if you don't have the special thin wrench, a 32mm headset wrench from your local bike shop works perfectly. Oh, and remember it's a LH thread.
Yep, it's dead. Should be hard to stop it. Most of the viscous fans I've had are basically locked on for the first minute or two of operation, then loosen up. Then they tighten up again when the engine gets hot. Shouldn't freewheel for too long when the engine is shut down.
The aux fan should be enough to keep the AC cold unless it's really, really hot out, so I'd be looking elsewhere for your issue.
I am not a big fan of those BMW AC systems. The evaporator cores love to get leaks and they are harder to dig out than a fried clutch.
I think you're compressor is slowly giving up the ghost. But I would spend the $15 to add a can of auto-shop refrigerant and see if that gets it cold again. Either way, for some reason 700 RPM isn't spinning the compressor pulley enough to adequately repressurize before the evaporator, but 1,800 is enough to do the job, apparently. Or maybe the drier is getting restrictive? As you said, lots of possible diagnoses. Good luck!
Oh you probably already know this, but the Bimmerforums classifies always has good used AC systems for sale cheap. We take them off E36's when we strip them for track, and there's nothing fun we can do with them.
Is the auxiliary pusher fan working? That is the fan responsible for keeping the condenser cooled.
The aux fan on my e46 only worked on low speed and A/C performance was poor until freeway speeds. Converted to the single electric puller fan that manuals came with and problem solved. Cut down on the fan clutch noise and improved efficiency by about 1 MPG.
