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  #1  
Old 09-26-2021, 11:07 AM
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AC volume and balance

Hey guys,

I have a 2012 X5 5.0i with the m-sport package which is mostly pretty awesome; however, whenever my daughter turns up the ac in the back the AC in the front goes down to pretty much nothing. I took it to the dealership service department and they insist there is nothing out of spec on my AC.

I find it hard to believe this is normal. I’m in south Florida and while what air does come out of the ducts seems cool the overall cooling is completely inadequate. With the AC on in the back the front vents don’t blow hard enough to get enough air on my head to fight off the heat coming down from the roof. With the dealer uninterested in fixing it I thought I would ask if anybody here has any useful information before I start looking for an inde shop that can help.
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  #2  
Old 09-26-2021, 11:42 AM
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Start with set the controls to control rear seat from the front then use common sense to get even air flow.

It's entirely impossible to cool a car to 60f off its hot outside.

Start with all controls on auto, make sure the vent control mix for the front seat is a couple spots into the cold passenger and driver then hit auto so fan speed is automatic.

Press auto repeatedly until intensity says medium.

Set temp everywhere to 74F (23c) and wait to stabilize when the fav speed drops to where you can barely hear it. Then you can slowly go lower or change the vent mix a little cooler.

I find the side vents a little week in our '12 50i, so I closed the center dash vents to get a little more even cooling in the front seat.

Once you get the front under control with front control of the back seat then do some back seat testing: set that to auto and 74F also and see if you can get it to self regulate.

I see this sort of thing all the time. "max Ac" is meant to run for 5 minutes. Also, never sure why people fight with manual fan control when a car has auto climate. Set it forget it.

If you can't get front to work properly with this testing method the blower or blower unit (FSU) isn't working properly (or something like evaporator not cold enough).

Start with the test method described and post feedback.
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Old 09-26-2021, 11:55 AM
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Another big no-no is to try to use recirculated air all the time. Make sure that is set to auto. You should have a button on the steering wheel to adjust that.

Again, helpful to initially cool the inside air but limits the total air flow.

Get everything to automatic and 74 to start with. It's the number pros use as a baseline in houses and usually as high as 78 is comfortable once the AC removes the humidity.

I have e53 so I don't have the intensity setting so I start at 77 when it's hot outside until the car gets the temp under control and bump down to 74-73 after.

Wife's 50i I leave at 73-74 almost always and just change the vent mix to change the face air temp up and down add needed.

If you are new to the platform there is a very good chance the dash mix is just set hot and keeping you from getting cool air.

https://g05.bimmerpost.com/forums/sh...68&postcount=5

That's the long way to get there.

The short cut is to hit the vent mix button on each side of the car but warning that disables auto control so you have to hit auto afterwards.
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Old 09-26-2021, 11:55 AM
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Hey Andrew,

Thanks for the feedback. I think I kind of take it as you’re voting that the AC in the X5 5.0i is incapable?

I’m a big fan of auto AC controls if they work. I used to have a 94 Subaru SVX. It was an early example of Auto AC control and it worked fantastic. I set it at 74 and that was it. It controlled the fan automatically so it didn’t blow hot air in your face before the AC was able to cool it and from there would change the fan speed as needed to very efficiently reach and maintain that 74 degrees.

My X5 does not do that. My wife drives an SUV too. We have no problems figuring out how to work the AC in her car. It doesn’t seem like rocket science to me. She immediately starts complaining and reaching to mess with the ac settings anytime she rides in my x5. The AC in my car is inferior compared to any other car we own or have owned—but again the dealer says it’s fine.
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Old 09-26-2021, 12:29 PM
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Quote:
Originally Posted by andrewwynn View Post

If you are new to the platform there is a very good chance the dash mix is just set hot and keeping you from getting cool air.

https://g05.bimmerpost.com/forums/sh...68&postcount=5

That's the long way to get there.

The short cut is to hit the vent mix button on each side of the car but warning that disables auto control so you have to hit auto afterwards.
I have the mix set all the way to cold. With the rear ac turned off the front works acceptably, not impressively, but acceptably. The volume and temperature of the air coming out of the dash is capable of reaching the front passenger’s heads and fighting off the heat coming in from the roof as long as the rear ac is turned off. Turn on the rear ac and the more you turn up the fan in the back the less you get out of the dash. It becomes a battle between the back and front seats to get enough air to fight off the heat.

What’s particularly troublesome is there’s a point where the use of the rear fan takes away enough output from the front that the air in the front no longer comes out with enough velocity to get up to head level and overcome the heat coming in from the roof (but the whole thing still makes lots of noise).
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Old 09-26-2021, 12:52 PM
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Yeah that sounds like FSU/blower.

Do you have access to a different similar car for a control?

Also "all the way" is rarely helpful long term, but the mix to cold in Florida may be exception to the rule.

Is the problem almost only the air volume? And at what setting for air intensity and what temp?

"Max" is "wrong answer". Start with everything at full auto and fan speed set to intensive, temp set to 74 make sure auto is lit on left and auto recirculation is set.

Then once the front is caught up turn the temp down a couple. I find in 90° heat I need it set to 70-72 here.

Next go to back seat and set to auto and 74. If the fan speed is super high then try 77 until the fan stabilizes. Once the temp gets closer to set the fan speed should slow down.

It "feels like" you aren't getting full speed on the front blower and without a control to compare it's difficult to confirm.

What scanning capability do you have? My scanner will send speed requests to the blower directly.

Do you hear the blower keep speeding up the full range of speed?

If a temp sensor is broken and the car thinks it's colder than reality, that can cause blower speed problems but only on auto and I'm pretty sure you've tried full fan speed or "max" which don't use that will not help you.
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Old 09-26-2021, 01:01 PM
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Originally Posted by andrewwynn View Post
Yeah that sounds like FSU/blower.

Do you have access to a different similar car for a control?

Also "all the way" is rarely helpful long term, but the mix to cold in Florida may be exception to the rule.

Is the problem almost only the air volume? And at what setting for air intensity and what temp?

"Max" is "wrong answer". Start with everything at full auto and fan speed set to intensive, temp set to 74 make sure auto is lit on left and auto recirculation is set.

Then once the front is caught up turn the temp down a couple. I find in 90° heat I need it set to 70-72 here.

Next go to back seat and set to auto and 74. If the fan speed is super high then try 77 until the fan stabilizes. Once the temp gets closer to set the fan speed should slow down.

It "feels like" you aren't getting full speed on the front blower and without a control to compare it's difficult to confirm.

What scanning capability do you have? My scanner will send speed requests to the blower directly.

Do you hear the blower keep speeding up the full range of speed?

If a temp sensor is broken and the car thinks it's colder than reality, that can cause blower speed problems but only on auto and I'm pretty sure you've tried full fan speed or "max" which don't use that will not help you.
I have an icom and istad and istap (and all the rest of the diagnostic software that typically comes on an ssd with bmw diagnostics). With the amount of noise the blower makes I have to believe it is spinning at full speed. My assumption has been that there is a flapper somewhere restricting the overall air volume below what it needs to supply both the front and back.

I try to leave it set to auto, intense, 74 degrees. If the rear ac is turned off that more or less works. Performance isn’t good enough that anything less than intense would be considered.

Last edited by longassname; 09-26-2021 at 01:09 PM.
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Old 09-26-2021, 01:38 PM
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AC volume and balance

Try to back off from full cold on the vent mix. Faster warmer air will transfer more heat. (from you). Eg slow moving 50° air that never reaches your face will not chill you as well as 60° air that does.

On auto and 74 where is the fan speed and will the fan speed speed/slow while changing temp?

I need to use 72 when the sun is beating on me but rarely much below that.

My wife's previous car the cabin temp sensor was weak and we would have to set lower than desired for ac and hotter than desired for heat.

On my car it will get confused once in a while and a quick flip of max on and off will snap it out of its confusion.

Use a sheet of tissue paper (or anemometer if you have one) to see if you are losing air speed or just temp up front (also get some temp measurements). "feels warm" not a diagnostic tool.

Once you get front fairly cooled off, jump in the back and turn up the intensity slowly and see if there is some setting that is the no-go level.

I have a feeling the dealer did not do the objective test Doug described but you can do it yourself.

If I can't get 50f out of my vents I rework my AC. Usually it's 42 or less in the center vents. If you don't have cold enough evaporator (test software will tell you), won't matter how fast the air, it will feel not fast because it's hot.
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  #9  
Old 09-27-2021, 12:45 AM
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TL;DR


BMW publishes specs on AC system performance. Did the dealer test these?

Doing an evac, leak test and recharge is $150-200 (well, OBVIOUSLY not at a BMW "dealership service department") Worth doing, IMO
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Old 09-27-2021, 09:11 AM
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Quote:
Originally Posted by ard View Post
TL;DR


BMW publishes specs on AC system performance. Did the dealer test these?

Doing an evac, leak test and recharge is $150-200 (well, OBVIOUSLY not at a BMW "dealership service department") Worth doing, IMO
I’ll be paying that for nothing just to get my car back this am. I have no idea what they did before telling me my AC is fine except take a video of my tires and brake pads and send it to me like I should be impressed they have a lift. This is my second time going to South Motors BMW Service and my second time having to take my car back without authorizing any work. I have a leak from the turbo oil return manifold which they miss-diagnosed as valve cover gaskets and offered to replace for $2900 and the FRM has my right headlight shut off due to a “supply side short” which they diagnosed as a xenon control module and quoted $1800 to fix. I guess they want to replace the whole headlight. I’ll install a new module myself. I don’t see $1500 to r&r a headlight assembly.

I need to look for a good inde shop today to deal with the AC. I’m happy to pay professionals with the specialized equipment on hand to do things well and efficiently. I’m not happy to pay people who always seem to come up with the wrong answer.
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