Converting the OEM USDM Q45 HVAC display to Celcius from Fahrenheit

[Infinitiguy19]

Many have wanted to convert there OEM USDM Q45 HVAC display to Celsius and I want to help. With the help of Heath AKA Q451990 I think this MAY be possible. I say MAY because I see on my display there is a small "C" for Celsius. If Heath could provide me with some pictures of the board or even if he were to take a closer look at the board I think we can finally confirm or deny this to be possible.

I think this is possible because if there is one thing automotive manufactures like to do is save money where they see fit. And making two boards one for LHD* and one for RHD* would be in there best interest. I have seen many examples of this but one notable one is the fact the the same mirror switch is used power folding mirrors as well as heated mirrors.

Now to be fair I have no interest in this modification for myself because I am used to Imperial units but I like to help others.

*LHD=Left Hand Drive*RHD=Right Hand Drive

[RustyBucket]

IMO, it would probably be easier to find a heater control unit from Canada and swap it in.

Whether to display Celsius or Fahrenheit is likely programmed into a chip on the controller board and can't be changed.

It is possible that the chips are all programmed the same and you have to change a jumper or something to switch between display modes. You'd have to look at a controller board or a schematic of the controller board to know if that's a possiblity.

[Q451990]

Per an old post (maybe so old it was on the Yahoo board) by Jerry Tucker, the USDM boards will display Celcius if you solder a component to a different location on the board - but I can't figure it out.

I tried something on one board and cooked it... On Maximas of a similar year, there is an unused pin on the connector that's grounded on cars with Celcius - but from what I can tell that's not possible here.

I think the best way to figure this out is if anyone has a CDM market Q and would be willing to either take VERY detailed photos of their controller internals - or send it to me, and I could probably figure it out.

Heath

[Infinitiguy19]

Well I have 12K posts from the Yahoo board but to search them is another thing. Its not thats its a lot to look through but the organization is a cluster f***.

I looked through the posts already that I downloaded from the Yahoo board and there is nothing there.

But Heath what your saying sounds like something Infiniti would do. Otherwise why would they want NEC (maker of the (IC's*) for some control units of the Q45) make two and not one? As I said Infiniti would save money making some things while focusing there money on something like say the engine.

I wish I had a spare HVAC unit I could just open up, maybe junk yard time.

[yiannitQ45]

I picked one up for 20 at my local junkyard

[Infinitiguy19]

Hey Heath any luck?