12 Button Auto On-Off Climate Control HVAC Retrofit Pictorial DIY by delmarco

By diyauto
( 4 )

7 minute read

BMW E46 12 Button Auto On-Off Climate Control HVAC Retrofit Pictorial DIY

Compliments of delmarco @ bimmerfest.com


Upgrade your Old Style 10 Button Climate Control Unit to the new style Automatic Auto On-Off 12 Button Climate Control

Starting during the production month/year of 03/2003 BMW redesigned the Automatic HVAC Climate Control in the E46 BMW 3 Series cabin. The new style 12 Button units are plug and play swappable with the older style 10 Button units and will replace the older units completely. 

If your 1998 to 03/2003 BMW E46 was bought secondhand and came with a new style unit this means that the original HVAC unit was replaced with a new style unit by the previous owner or if you find your 03/2003 on BMW E46 has the older unit then the same maybe true for you and the previous owner replaced the newer unit with an older style unit for whatever reasons.

VIDEO THREE: Comparing Physical Design of 10 and 12 Button Units.

VIDEO FOUR: Showing New 12 button style Climate Control.

Main Reasons to do this upgrade:

1. Aesthetics of button layout on new style units make more visual and functional sense.

Older 10 Button Style:

Newer 12 Button Style:

2. Due to the MUCH smaller footprint that the new style climate control uses in the radio/dash area cavity those looking to free up space for Navigation Retrofits, Dynavin and other wire-intensive double din projects will find lots more free space behind the dash with a new style control than the bulky older style.

3. It may add the Auto-Turn-On feature that the newer HVAC Climate Control have to your car. So when you enter the car the Climate Control will turn on by itself and automatically regulate the cabin temperature.

4. It is a relatively cheap upgrade. I got my new style unit in the forums classified for around $25 and you can find the new 12 button units on eBay from $10 and up for a good condition used one. Plus the DIY requires a basic screw driver, little car knowledge and takes minutes to complete.

Parts Number for new unit that I retrofitted into my car:

Parts Number for old unit that was in my car:

Parts Number with Production Date Guide for ALL YEARS E46 HVAC Units:

Everything you will need for the DIY:

Here are the basic steps to insure your installation goes as plan:


Before you proceed to disconnect the HVAC unit make sure that you unplug the battery or else the new unit will not work properly (don't ask how I found this out - lol ).


VIDEO TWO: Showing New 12 button Style Pre-DIY.

If your car has the regular BMW E46 Business CD53 or Cassette Radio then the removal of the old HVAC will be as shown below. 

Follow these steps:

You do not have to remove the upper vent-this picture below was borrowed from my Radio upgrade DIY thread. Again you DO NOT have to remove the upper vent for this HVAC upgrade DIY:

If you have an in-dash factory navigation or double din unit then the removal of your old E46 HVAC will be different. Follow these steps below:



When said and done: