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| BMW 540 Cooling Fan Replacement |
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Fair
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03.01.06
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The air conditioning on Fair's 1998 BMW 540i started to get flaky in the summer of 2004. It just wasn't cold enough, especially as the summer months rolled in. Worked fine on the highway, but didn't always blast me with arctic goodness when driving in town. I assumed it was just low freon, and had it tested (had neither the gauges or time). The shop said it had plenty of high-side freon pressure but insane temps, around 450°F. This is way too high.
This pointed to the real problem: a dead electric, auxiliary cooling fan. There's a big honkin' mechanical fan for primary cooling of the radiator but there's also an auxiliary electric fan that only comes on when the a/c is turned on, and an added heat load goes into the condenser/radiator. The non-BMW dealership shop wanted $550+ ($350 + 200 in labor) to replace this fan. No thanks.
How hard could it be? Fair ordered the part ($250, complete with BMW part number) and its DIY time. Luckily it was a fairly straight forward job. Ordered the $109 set of Bentley service manuals for the 1997-2004 E39 BMW 5 series, to "show the way", or so we thought. This 8 inch thick stack of shop manuals has ABSOLUTELY NOTHING air conditioning related in them, so the limited bumper removal instructions and illustrations was all we had to go by.
Fair had a camera and web space to burn, so we put together this quickie install overview. This barely qualifies as a "tech article" but it does illustrate this install better than Bentley's manual. It is also useful as a visual guide for anyone doing an M5 front end conversion or headlight assembly swap, as the front end removal is all the same - and its easy. Fair spent all of 2.5 hours doing this swap, and easily 1.5 hours of that was cleaning and detailing. That is his sickness.
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general directions
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The bumper and attached bumper cover came off fast; about 6 small screws, 4 plastic rivets, two small grill inserts, the two fog lights, and two big bolts - then the entire 21 pound front end just slides right off. Could literally do this in under 10 minutes flat, now that we know the process. Didn't even need to jack the car up, like the manual says. This same procedure was used to remove and replace the front end on Redwood's E46 a year later. BMW front ends are generally very easy to remove.
The next to come off were the headlight assemblies (4 screws and 3 wiring connectors each), then the air inlet hose (that snakes around under the right headlight; three bolts and a hose clamp), and the front fan shroud (2 screws and 4 plastic rivets). Once all of that stuff is out of the way, the fan is easy to remove and replace - just 4 bolts and one electrical connection.
For this pictorial overview, Fair cheated and took everything off first, then took pictures of it all going back on. Use your imagination, people. We were truly shocked to realize how nicely everything fits together, and the small engineering touches that really make working on this car a pleasure, on the rare occasions where none of the plastic pieces break when removed after 5+ years of street use.
Thanks to Tommy and Hanchey (they both suggested this source) for hooking Fair up with BimmerZone.com. Their online catalog is great; ordered the parts at 4pm on a Thursday and they were on the doorstep at noon the following day with free UPS Ground shipping. Everything had a BMW part number and sticker, too, and the cost blew the dealer's prices all to hell.
So, there you have it. A pictorial overview of the electric fan swap on a 1998 BMW 540i. Hope it helps someone? Mostly we save these pictures for ourselves - for the next time we do a similar job. Its our online memory cache.
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