Heater blower gone mad
 

A year ago I replaced the heater blower fan in my X5. In the last few weeks it's been going mad - runs OK for the first 10 minus then it speeds up and slows down constantly.
Has the FSR gone crazy? I'm sure I swapped it at the same time as the fan but I found 2 in the garage that are brand new and not OEM so maybe I didn't. What dya reckon?

I would swap in different FSU. With experience it's a five minute job

same difference
 

Apples to oranges, but the same anyhow.

I've got a '98 GMC Sierra pickup that has a similar problem, for several (maybe even 8-10 years, I forget). The blower will run fine for awhile, slow down , speed up, then quit. I turn off the blower for a minute or two, and sometimes it'll work fine, or I have to hunt for the speed it likes: low, medium, medium-high, and full speed. Or it won't choose to blow at all, and I have to repeat the process.

Blower: I've tested and replaced one blower that was going bad, and replaced its' replacement with another, though I didn't think it was drawing too many amps, and finally stopped replacing them. Fan speed problem stayed the same.

Control Unit: Same procedure. Replaced the original with a Dorman piece, then with another A/C Delco unit, and the fan speed problem persists.

Resistor (hedgehog): You guessed it, changing it makes no difference. I've used many (and have a new spare in the glovebox), practically one per every two years, and the fan speed problem always crops up.

Possible reason: After years of research, I've decided that GM used too thin of a gauge of wire(s) in the harness to the resistor and blower, and that it gets really hot after a few minutes, and the fan speed "merry-go-round" starts again. The previousowner ALWAYS ran the fan on high (I know, I rode with him for 7 years before I bought it from him), because the vent arrangement isn't the best. So, I too, usually started with the blower on high, just to initiate cooling faster. But sometimes, even if I used low or medium, the problem would start as well.

Possible (temporary) solution: A few times, after I thought I knew what the problem was, I would start out on each fan speed and run it until the problem started. Eventually, I found that "medium-high" was the sweet spot, and the problem did not happen. I now leave the fan on med-hi, and made sure that my wife does the same (it's her back-up vehicle), and the fan has worked OK for months now.

Possible (permanent) solution: There's an upgraded wiring harness on the market, with better connectors and thicker wires, that I'll buy the next time the fan speed problem happens, I swear. I haven't replaced the harness yet, because it's really buried under the dash, I'm old and don't work well under dashes anymore, and my penchant for work-arounds tells me to wire the blower directly to power...but my wife says no. Oh well, I'll get around to the proper fix some day.

My problem not as drastic as your but ...https://r.tapatalk.com/shareLink/top...ink_source=app

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Contact problem: deoxit gold


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Yeah, I've got it!
Use on the fan connector right?

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FSU plug yep. Just unplug replug a few times usually scrapes off enough contact gremlins to make it work for a while but deoxit will actually fix it if contact resistance is the problem


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Good reasonable sound suggestion thanks [emoji106]

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Hopefully that does the trick

I had one FSU overheat and i left it dangling in the foot well it stopped overheating. That's another failure mode to be aware of