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I have a 2006 BMW 750i with what I feel is an issue. Car is still under warranty. When driving down the road, (in my case in the Houston area) and I have the a/c on (on "auto") the a/c will quite frequently stop running, and the air coming out of the front vents will shift to the defroster, and hot air will come out. This will happen for about 5 to 7 seconds, meanwhile all the lights on the front of the console show that the a/c is stil on(on auto). After the 5 to 7 seconds, the air will again shift to coming out of the front vents, and will bve cold.. This can happen as much a 4 of 5 times in a 5 to ten minute timeperiod.
Car is at the dealer right now - and they say it is normal, that another 750i (same year) does it as well. I think their wrong. No car should be swithing back and forth like that, that many times, and throwing out hot air.......

Submitted: 101 days and 6 hours ago.

Category: BMW

Value: $20

Status: CLOSED

Year: 2006
Make: BMW
Model: 750i

Already Tried:
Nothing - under warranty - took it to the dealer - they have had it for 3 days, and just called me to tell me that they duplicated the same thing on another 2006 750i, so they are thinking it is normal...

Posted by Bill 101 days and 6 hours ago.

Answer

Good evening, I hope I can help you.

Unfortunately you are wrong and dealer is correct.

There are mini pumps that suck up air from both footwell areas to measure the temperature.

The aircon is an air temp regulator.

If you set the temp to say 5 deg C the sensors will pick up the air temp and compare it with the setting you have requested.

If the temp falls below the setting the system will adjust by allowing hot air in until the system detects the correct temp.

Its actually a climate control system and not an aircon fridge.

Bill.

101 days and 6 hours ago.

Reply

Don't disagree with your reply - but, with the a/c on auto, the air should be regulated back via the system in allowing heat as well as a/c to come in to the car via the front vents (or wherever you have the air going to). In this case, in "auto" mode, the a/c should be regulated as you say to get to the desired temp in the car by varing the air in the car with both heat and a/c via the a/c system. I do not believe the entire a/c system is designed to shut off completely and hot air directed to come out of the defroster vents full blast for 5 to 7 seconds, THEN go back to a/c out the front vents.... If you have the vehicle a/c system on "auto" it will regulate the air tempt to the desired temp you want by mixing the air to get to the temp you want.... Never saw a system do that by shifting the air off - then balsting hot air out of the defroster for 5 to 7 seconds to get the desired air temp in a car!!

Posted by Bill 101 days and 6 hours ago.

Answer

If you don't believe it, ask the dealership to show you the other vehicles doing the same.

You could also try it the other way. On an extremely hot day set the temp to max heat and see if it blows out cold air then hot air in short bursts.

Bill.

Edited by Bill on 8/12/2009 at 10:09 PM

101 days and 5 hours ago.

Reply

I guess my whole issue with this is that it just started doing it... I have owned that car for over 2 years, and it just started doing this about 2 months ago, and it is doing it more and more frequently.... back and forth, air one moment - heat the next, air then heat... Stymied in the fact that it never did it until May of this year, and now it does it all the time.....

Accepted Answer

Have you considered that your car had a fault before and has now rectified itself.

I would ask the dealer to show you the other cars doing the same. Then you can put your mind to rest.

Bill.

Accepts:
Expert:	Bill
Pos. Feedback:	100.0 %
Answered:	8/12/2009

ASE Certified Technician

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Optional Information

Year: 2006
Make: BMW
Model: 750i

Already Tried:
Nothing - under warranty - took it to the dealer - they have had it for 3 days, and just called me to tell me that they duplicated the same thing on another 2006 750i, so they are thinking it is normal...

Answer

Reply

Answer

If you don't believe it, ask the dealership to show you the other vehicles doing the same.

You could also try it the other way. On an extremely hot day set the temp to max heat and see if it blows out cold air then hot air in short bursts.

Bill.

Edited by Bill on 8/12/2009 at 10:09 PM

Reply

Accepted Answer

Have you considered that your car had a fault before and has now rectified itself.

I would ask the dealer to show you the other cars doing the same. Then you can put your mind to rest.

Bill.

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Year: 2006Make: BMWModel: 750i Already Tried: Nothing - under warranty - took it to the dealer - they have had it for 3 days, and just called me to tell me that they duplicated the same thing on another 2006 750i, so they are thinking it is normal...

Answer

Reply

Answer

If you don't believe it, ask the dealership to show you the other vehicles doing the same. You could also try it the other way. On an extremely hot day set the temp to max heat and see if it blows out cold air then hot air in short bursts. Bill.Edited by Bill on 8/12/2009 at 10:09 PM

Reply

Accepted Answer

Have you considered that your car had a fault before and has now rectified itself. I would ask the dealer to show you the other cars doing the same. Then you can put your mind to rest. Bill.

Related BMW Questions

Year: 2006
Make: BMW
Model: 750i

Already Tried:
Nothing - under warranty - took it to the dealer - they have had it for 3 days, and just called me to tell me that they duplicated the same thing on another 2006 750i, so they are thinking it is normal...

If you don't believe it, ask the dealership to show you the other vehicles doing the same.

You could also try it the other way. On an extremely hot day set the temp to max heat and see if it blows out cold air then hot air in short bursts.

Bill.

Edited by Bill on 8/12/2009 at 10:09 PM

Have you considered that your car had a fault before and has now rectified itself.

I would ask the dealer to show you the other cars doing the same. Then you can put your mind to rest.

Bill.