740 Heat on all the time?

[Toxicant]

I worked on a 96 740iL today with a A/C problem I was wondering if anyone else has encountered?

The complaint was not enough cool air so I checked it out and found it was a little low so I evac, and re-charge. Everything seems ok but I found that there seemed to be heat coming out of the defroster ducts. I moved the controls from 60 up to 68 and the heat seemed to lessen. I figured that BMW dirverted some warm air on the windshield to keep it from frosting up when on high A/C.

The system might work somewhat that way, but as far as I can tell the heat seems to be on at the same time as the a/c.

Has anyone run into this? I haven't got to involved with it yet but in the next day or so I'm going to have to figure out why.

Any help might make my day go much smoother!

Thanks in advance!

Tox!

[mando23]

Heated air is delivered not only through the defroster ducts but also, if you stay in the car long enough, you will notice hot air coming from the bottom panels; Whether the AC is on or off! Actually if you turn the front middle air-vent selector wheel towards the red (hot) dot, you will also get hot air through there too. What is actually happening is that the BMW HVAC engineers got a bit carried away and designed the 740 interior like that of an office buildings: A combination of hot, cool, and outside air to mix at some point (with the interior temperature sensor as the judge, not the driver) to give you the desired overall set temperature. The ONLY way to avoid hot air as mentioned, is to set the air delivery settings to the front air vents only (not the defroster ducts, and not the bottom panels) - Which means that the “Auto” setting for the air distribution is disabled while in that mode. Said settings allow you control of how hot the air should be and how much of it is discharged (out of the air vents anyway) inside of your car. You can still use “Auto” feature for fan speed though.

BTW: What I normally set my dials to, in SF CA. - avg. temp 60 deg F, is: No AC, outside air on, front air vents on, off for the bottom panels, off for the defroster ducts, “Auto” for the variable fan speed, and I do adjust the temperature from 65 deg to 70 deg. If the outside temperature goes above 70 deg, I activate the AC only then. Otherwise it is very uncomfortable to always have hot air in your face from the defroster ducts (or hot feet from the bottom panels) even though the TOTAL composite interior air temperature might be only 65 deg F as per your temp setting.

[Toxicant]

Thanks for the reply but you have got to be kidding me???

You really mean that BMW would design a car that you can't run the HVAC on full auto mode with out your far head and feet under the broiler?

Did you buy this car new? and have you had BMW check it out?

The car is my fathers and I'm a service manager in a Chevrolet dealership so I'm the guy to fix the problem

Hasn't anyone else with this model had this problem and complained to BMW??

If I had this problem with a new Impala or Silverado my customers would be screaming!!!

Somebody must have had this complaint and had it solved?

Thank you,

Ron

[jackhall]

I have the same problem, but it was not that way 6-months ago. The problem is intermittent and contrary to what the other guy says is normal-it is not normal. How did you fix the problem or did you?

Jack

[jkw1414]

I've had the same problem and have had to combat through the same methods. I've had it checked out by various certified and non-certified shops and they have all been baffled. Guess we're going to have to deal with it until someone tells us otherwise.

[libertylover]

Here's a link to a page with help on the IHKA system:
http://bmwe32.student.utwente.nl/