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7 Series - E38 (1995 - 2001)

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  #1  
Old 08-09-2014, 01:12 PM
JHains JHains is offline
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Location: Woking, UK
 
Join Date: Jul 2014
Posts: 14
Mein Auto: 1998 740i
Heater and A/C not working

Hi all,

I've an old 1998 740i and the heating and cooling on the car is not working correctly.

I've tried doing a few simple tests and I'm not sure they are helping me get confidence in what the problem is.

On the AC side of things then when I turn the AC on then the compressor does kick in and the electric pusher fan starts, there is charge in the system, when I put a pressure gauge on the low pressure side while the car was running it showed 35psi. This was also drained and refilled by BMW last year so I think it should be OK.

With the temp set as low as possible 16degC and the blower on full and the vents blowing only horizontally then when I switch the ac on then the temperature doesn't change noticeably but the speed of the airflow out of the vents increases...strange?!

If I then increase the temperature to 32degC on both sides then the speed of the flow out of the vents drops to nearly nothing....I can still hear the blower running but the air is not coming out from anywhere.


My only though is that one/some of the flapper motors are not working properly, are there any tests for these.

Any thoughts/tests/old threads I could do to diagnose further would be much appreciated.

Many thanks in advance.
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  #2  
Old 08-09-2014, 02:36 PM
Mayorchuck Mayorchuck is offline
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Location: Farley, MO
 
Join Date: May 2013
Posts: 779
Mein Auto: '96 740iL
Look at the first item listed under 'Maintenance" here:

http://www.magnum1.com/magnum/BMW-740/740_Pages/740.php
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  #3  
Old 08-09-2014, 05:00 PM
JHains JHains is offline
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Location: Woking, UK
 
Join Date: Jul 2014
Posts: 14
Mein Auto: 1998 740i
Quote:
Originally Posted by Mayorchuck View Post
Look at the first item listed under 'Maintenance" here:

http://www.magnum1.com/magnum/BMW-740/740_Pages/740.php
Many thanks for the link...will check out these dampers and actuators.
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