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2004 Outback H6 Sedan, 1996 Legacy Outback H4
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Discussion Starter #1
After a few different attempts at converting my car into Metric for temperatures, I finally got my hands on a set of controls from Canada. These controls are exactly the same as the US ones, except set to display Centigrade instead of Fahrenheit. Before installing the CDM unit into my car, I took a high resolution picture of the bottom of the circuit board and I sat down and compared them carefully.

The scale used is determined by one jumper on the underside of the circuit board. I have confirmed this with a 72311AE11D and 72311AE08B. From what I can tell, the 11x are USDM and the 08x are CDM. The letter just indicates revision/year. Both of these types are made by Calsonic Kansei. Denso branded units are significantly different, but I have only seen that brand on JDM units but there may be Denso ones in the US as well. This modification is not for Denso units, only for Calsonic units.

The conversion is extremely simple, one jumper wire in the R145 position. I have two pictures indicating where it is on the board.



Closer shot:


Simply solder a wire across the two pads, and voila... Metric readout!



I have confirmed that this is switchable even when on. If you were to wire a switch to each side of that resistor pad, you can switch between F and C at will.

Here is a video of me connecting and disconnecting while on, I did not have a switch handy so I just pressed the wires together.
 

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just FYI, I bought HVAC unit from European legacy. it works perfectly on my US Outback 04'. R145 circuit has a resistor due to which probably a conversion of F to C is made more precisely, because 75 F from your video does not equal to real 25 C, but to 23.8 C. Also when temperature dial is used the step is +/- 0.5 C

BTW the chip on other side of circuit board is different than that on US (F) version:
European version


US version:
 

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Registered
2004 Outback H6 Sedan, 1996 Legacy Outback H4
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620 Posts
Discussion Starter #3
My comparison is between the Canadian and the US version which uses the same revision of chip. Those two chips you pictured are off by one revision. Given that there is no top silkscreen on your US module, these are different years which explains that.

The resistor does not alter the temperature values, it is just a pull-down resistor to bring a digital pin low to tell the processor to go into metric mode.

The Auto HVAC controls are not exactly known for accurate temperatures, so I bet that Subaru just didnt care. For example. 1F =! 0.5C, but it does increment like that if you swap back and forth.
 
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