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Hello guys! I recently bought my first car. It's a 2012 BMW 535i GT Base. The thing only had 55k miles on it over 8 years. It's been 4 months now and it's been running great.

I changed the cabin air filter, the engine oil filter, engine air filter and the engine oil.

I took the car on its first long drive (SF to LA) and on my way back something weird happened. The AC stopped working. It had been parked in the sun all day (it is generally parked indoors when home). The AC didn't work the entire trip. As the sun set, the AC kicked back in. Since then, I've had this intermittent AC problem only during sunny afternoons. The AC works really well at night.

I took it to a BMW authorized service center and I feel like it did more harm than good. The guy just felt sketchy. But that could just be me(I'm generally skeptical of mechanics. More of a DIY person).
So he changed oil filter housing gasket and put in a new battery. It still hasn't solved the problem.

Do you guys think it is worth changing the blower motor and the resistor? I've seen the video on youtube with the guy changing the motor to solve the intermittent motor problem. My doubt is, why this happens only during the day and not at night?

Appreciate any help...
 

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First, I would think might be related to temperature and not daylight. Have you read for fault codes with a BMW specific scanner? The motor and resister will effect the blowing and not temperature. Did it just stop blowing or was it blowing hot? You need to describe “not working” more. Stopped blowing, blew heat and not cold, only works on one speed, intermittent, etc.


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Yes, it is temperature related. I haven't checked the fault codes yet. By 'not working' I meant it stops blowing air. Just no air flowing through the vents at all.
 

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Yes, it is temperature related. I haven't checked the fault codes yet. By 'not working' I meant it stops blowing air. Just no air flowing through the vents at all.


I would first want to check for fault codes and fuses but if it comes on at all it is getting power. For me in an E70, it would come on at whatever speed I set it to and originally would die after a few minutes. Then it stopped blowing after 2 seconds. I replaced the blower motor with a new one from Behr than came with a new regulator. It solved the problem. There can be several reasons for the behavior but for me it made sense to spend $120 for the blower and regulator instead of trying to electrically find the issue. I don’t know how easy the replacement is on the GT but for me it was 30 minutes. In my opinion, if it works and then dies it is one of the two and is worth the replacement. Mine lasted 172,000 miles.


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I find it odd that it happens when the sun is out. I am an OLD Mech, and in my day cars did not have all these sensors. I believe BMW uses a heat sensor near the dash that modifies the A/C system depending on Solar heat gain. Again, not up to date on the newest tech...I would Google or ask someone in the know about this.
 

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Hi Nikthemechanic,

Are you sure that you set your center ventilation grilles' knob to "blue" rather than "red" (right in the middle of the dash) by rotating it, before to start your Air conditioner ?

Cause this is one of the tricks related to almost all BMWs. Especially if you are not familiar with BMWs and if you forget to do that setting beforehand, you might get burn during summer time or might get frozen in winter...

Anyway if that's already done, first thing is to make an OBD Scan. if not available, check the fuse related to the blower motor first and if that one is also okay you might also suspect a leakage of cooling gase in the AC cooling system.

But, first thing is first... Check if the above is okay. if all is done and still no result get it to a service shop.

Good luck.
 

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As Nik stated the problem only occurs during Sunny days when the car is in the sun. As earlier stated it could be a Solar Heat Gain sensor somewhere in the dash. I have always used things around me to sometimes diagnose problems, if sensor is in dash maybe the sun is heating up the dash causing sensor to malfunction. Everyone has cardboard laying around, cut some to cover upper dash and use painters tape to hold it in place. If A/C stops acting up you have just narrowed your problem down at no real cost. Again, I am just guessing since I have been out of the Mech info world for a LONG time.
 

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Discussion Starter #8
Update:

Thank you everyone for your help. I ended up replacing the blower motor and the regulator. I bought the parts from FCPEuro. I also ended up buying the foam covering piece since every DIY video I came across had the foam disintegrating. I didn't need the foam filter part but the return shipping was too high to justify sending it back. It lies in the garage somewhere.

So I checked the blower motor. The shaft had rust. I imagine the rust creates resistance in rotation pulling more current from the battery and at that point the controller kills power to the motor.

The DIY was not that bad, took an hour though. It's just patience, there's not a lot of space around the blower motor assembly.

AC has been working great now. It's been over 5k miles since the fix. Thanks again.
 

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That just weird, never would have thought motor since you were stating only proplems on Sunny days.
 

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02/2012 X5 35d M57Y CPO 98K miles NOKIAN WR G3 12K miles
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That just weird, never would have thought motor since you were stating only proplems on Sunny days.
+1

Post hoc ergo propter hoc it’s obvious to even the casual observer. /sarcasm
 
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