Uneven and luke warm air distribution

Post by **Charles** » Fri Dec 30, 2016 2:44 am

To be precise, I am getting hot air through the passenger vent and the lefthand centre vent but cold air on the other side.

Any thoughts?

BarryM · Post by **BarryM** » Fri Dec 30, 2016 12:05 pm

Assuming you have dual climate control it sounds like the heater valve that sits near the passenger pollen filter in an E39. There are separate plungers/chambers for driver and passenger side, I don't think my descriptions are perfect but it's a starting point.

Post by **Charles** » Fri Dec 30, 2016 2:19 pm

BarryM wrote:Assuming you have dual climate control it sounds like the heater valve that sits near the passenger pollen filter in an E39. There are separate plungers/chambers for driver and passenger side, I don't think my descriptions are perfect but it's a starting point.

Sounds like a good start to me - thank you

Post by **Charles** » Mon Aug 21, 2017 4:03 pm

Bit of a thread resurrection but after months of searching online, I believe I have solved the problem

Not only was I getting uneven air distribution across the centre vents, there was nothing going up or down (even when using the specific direction buttons on the control panel) and the maximum heat was luke warm at best.

The cooling system has been bled, the heater control valve has been checked, the final stage resistor eliminated from the equation and short of stripping the dashboard to investigate each of the stepper motors, I was about to buy a secondhand control panel to see whether that made a difference before committing to major surgery.

Anyway, I finally happened on an excellent YouTube video - here - which looked extremely promising.

Today I popped out the control panel, checked the M-Bus connection and did the hard reset of the control panel (remove and replace the main power socket) and I now have hot air, cold air, up air, centre air, down air and every possible combination of air you can think of.

As I am sure you can imagine, I am delighted

Post by **Charles** » Wed Dec 20, 2017 1:40 pm

After my last post and with the colder weather now here, I realised that the heater function is still not as it should be. The air distribution is still uneven and remains luke warm at best and I have started noticing the fan speed cycling up and down.

Now, conventional wisdom is that the varying fan speed is a sign that the final stage resistor (the hedgehog) is knackered, but I decided to try another route - particularly as I am about to upgrade the radio with a Dynavin N7 unit which will require relocating the climate control panel to above the ashtray.

I discovered that there is an upgraded control panel for the E46 - 12 button rather than 10 button type - which is significantly more compact than the current one in terms of the space it occupies behind the dash, which will help with the relocation.

More importantly, the ventilation seems to be working as it should through all the vents and gets very hot

AG · Post by AG » Thu Dec 21, 2017 4:40 pm

Charles, where did you hear about the upgraded part? And where did you get it from?

Post by **Charles** » Thu Dec 21, 2017 5:19 pm

AG wrote:Charles, where did you hear about the upgraded part? And where did you get it from?

I was poking around the web and came across the following page

As for buying one, I was lucky to find one specifically listed with a BMW breakers yard, rather than trying to track one down via cars they had in stock. Cost me Â£35 including postage.

Basically, any E46 built post 03/2003 should have the newer 12 button unit.