A/c - Electric fan doesn’t work until I speed up?

Aferanova · 09-11-2020, 10:21 AM

I wanted to post an update that i got this fixed! The root cause was indeed the battery.

I trusted my gut that it was likely the battery... it just made sense to me of why the AC once working would work well for 12-15 hrs, then any longer than that and it wouldn't work until speeding up which must've been giving enough power to the system to let it operate the fan & compressor properly. For reference the battery i pulled out was an 80aH while the car was still coded as 90aH ---and a european shop had installed it! Maybe that has something to do with the error or the only 3 yr life.

I went and just bought a new battery from the local bmw dealer - for reference, i bought a 105aH AGM for $190 since the standard 92aH AGM is $250. Its compatible so i went with the bigger one for less money.

I coded in the new battery size using ESYS under CAS module > 3702 > VCM_BATTERY_CLASS > and selected 105ah_agm

Then i pulled up ISTA+ and did the registration of the new battery (engine had to be off).

Now the AC blows ICE cold from the start. Thanks for all the help. hope this helps someone else in the future, and happy to have avoided the shops who, while they registered the last battery, they didn't code in the size first!

Wgosma · 09-11-2020, 10:31 AM

Thanks for the update, bit surprising to me your car did not exhibit other electrical related issues due to low battery output. I've read couple of forum posts that indicated battery life is shortened if not properly coded, that may have been yoiur issue- battery should typically last 5+ years in most cases. You got very decent price on that new battery from the Dealer!

Wgosma · 03-23-2021, 04:13 PM

You might need to have a shop load test the electrical system to solve this one.

09-11-2020, 10:21 AM	#23
Aferanova Private 34 Rep 57 Posts Drives: 2013 BMW X6 xDrive50i Join Date: Jan 2015 Location: Cincinnati, OH iTrader: (0)	SOLVED I wanted to post an update that i got this fixed! The root cause was indeed the battery. I trusted my gut that it was likely the battery... it just made sense to me of why the AC once working would work well for 12-15 hrs, then any longer than that and it wouldn't work until speeding up which must've been giving enough power to the system to let it operate the fan & compressor properly. For reference the battery i pulled out was an 80aH while the car was still coded as 90aH ---and a european shop had installed it! Maybe that has something to do with the error or the only 3 yr life. I went and just bought a new battery from the local bmw dealer - for reference, i bought a 105aH AGM for $190 since the standard 92aH AGM is $250. Its compatible so i went with the bigger one for less money. I coded in the new battery size using ESYS under CAS module > 3702 > VCM_BATTERY_CLASS > and selected 105ah_agm Then i pulled up ISTA+ and did the registration of the new battery (engine had to be off). Now the AC blows ICE cold from the start. Thanks for all the help. hope this helps someone else in the future, and happy to have avoided the shops who, while they registered the last battery, they didn't code in the size first!
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09-11-2020, 10:31 AM	#24
Wgosma Lieutenant Colonel 811 Rep 1,913 Posts Drives: 2012 F25 X3 28i (N52) Join Date: Sep 2018 Location: Northern Nevada iTrader: (0)	Thanks for the update, bit surprising to me your car did not exhibit other electrical related issues due to low battery output. I've read couple of forum posts that indicated battery life is shortened if not properly coded, that may have been yoiur issue- battery should typically last 5+ years in most cases. You got very decent price on that new battery from the Dealer!
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03-23-2021, 04:13 PM	#25
Wgosma Lieutenant Colonel 811 Rep 1,913 Posts Drives: 2012 F25 X3 28i (N52) Join Date: Sep 2018 Location: Northern Nevada iTrader: (0)	You might need to have a shop load test the electrical system to solve this one.
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