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-   -   No heat from dash great heat from defrost (http://www.bimmerfest.com/forums/showthread.php?t=581709)

bearsbmw 11-15-2011 06:21 PM

No heat from dash great heat from defrost
 
Hi
Got great heat quickly from the defroster,but almost no heat from any of the dash,controls,any ideas?

M.Wong 11-16-2011 05:25 AM

What kind of car do you have? A BMW? A 7er? A 1995 to 2001 7er?

bearsbmw 11-16-2011 06:39 PM

Hi
I have a 2001 740i ,good heat quickly from defrost,but the drivers side dash vents are cool,pass side slightly warm,with temp controls set at 90!

Muhammad's 740i 11-17-2011 12:14 AM

I have the same problem but there's no heat coming on defrost on too. The temp I set is on 90 degrees but still no luck. Would highly appreciate if somebody can help. It's 2001 740i. My car is equipped with heated seat so that's what I'm using so far

azyankee7 11-18-2011 08:42 PM

My car also gets heat from the defrost but not the vents

nsschris 11-18-2011 10:18 PM

I also have this issue. well very similar. Defrost is hot and everything but the vents only get slightly warm. but ocasionally they will heat up nice and hot.

joyism5 11-19-2011 05:48 AM

Did any of you guys had the fresh air filters and cabin air filters changed?
They are 4, 2fresh air filters on the hood, and 2 cabin filters (under the dashboard one on driver side and one on pass. side). It is essential to have filters change every year or 15k miles depending on the dusty driving conditions. Lift the hood, and on the firewall there are 2 door flaps for the air duct. Push the doors and check for debris or strange object in there.

Microfilters are used in BMW climate control systems, this includes all vehicles produced
after 9/91 (except E30) .In addition, all E31 vehicles have been equipped with microfilters
since start of production.

Fresh air is continuously filtered through the microfilters. Never operate an E38 without the microfilters installed,
There is the danger of water being drawn into the heater and/ or damage to the electrical
system.

The microfilter is designed to trap potentially iritating types of particles with very high efficiency.
Examples :
-Pollens
-Spores
-Dust
-Vapors
-Floating air pollution
-Bacteria
-Viruses

Under normal operating conditions the microfilter(s) should be replaced every Inspection I
and II (also every Oil Service 99 MY), except for M roadster or M coupe.The actual
service life of the microfilter depends on the amount of contaminant and air flow rate
reduction complaint, therefore the replacement interval may be more frequent in dusty
operating conditions.
E38 models have additional filters for the recirculation air inlets which require replacement
at every second inspection II.

Now, while you are changing the filters , check the air duct for leaves or an kind of dirt. If that doesn't solve the issue you might have a door flap actuator problem or the AC control panel. More info about the air distribution in these cars :
http://www.meeknet.co.uk/E38/
http://www.bimmerboard.com/forums/posts/679901
www.e38.org
Microfilter replacement :
http://www.bimmerboard.com/forums/posts/348259
http://www.e38.org/gsussman/740i_rec...eplacement.htm
For those that the defrost is not working at all , the defrost button should be removed and check the OHM resistance with a voltmeter, like described here http://www.laczik.org/BMW/repair/E38_AC/E38_AC.html. If there is no resistance at all , this might pin point an door flap actuator failed.

joyism5 11-19-2011 05:51 AM

@ azyankee7 & nsschris : yours is similar with this http://www.laczik.org/BMW/repair/E38_AC/E38_AC.html

joyism5 11-19-2011 05:54 AM

@ bearsbmw : I would suspect a door flap actuator went bad or air duct is obstructed. Check air filters first.

joyism5 11-19-2011 05:58 AM

Muhammad's 740i : defrost switch is working properly? Do you hear the blower going faster when you push the button?

Muhammad's 740i 11-20-2011 12:10 AM

Yea everything works, when I press the defrost button it goes all the way up but the normal air comes out not warm. It's same for the heater too.

apocolyps3 01-28-2013 10:37 AM

So....did anyone get the chance to fix this issue? I have the same problem too.

GVC 01-28-2013 05:00 PM

I'm having the same problem. Clean fresh air filters.

BMWFatherFigure 01-28-2013 09:48 PM

Filters and doors plus debris on the heat exchanger - my guess.


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