WTB 550 hvac control, working or not

You looking for the lower box with all the electronics?

 

Steve, I would be interested in learning what you come up with to do this. I agree, the gap in speeds between 3rd & 4th is too big. If changing a resistor, etc. in that temperature control "console" could easily increase 3rd speed, it would be great. I've sent an email off to Diavia about this, but don't hold much hope of hearing from them.

FWIW, here are a couple pix of the little HVAC control board (not the ECU itself, of course). I've followed the traces, and it appears the fan speed switch causes the resistance to vary on all the output pins of the board's output connector, so it's not too straightforward to figure out which pins control what.

That R28 in the top photo isn't actually a pot, only a selector switch, and I "suspect" that by changing the resistors to the right of it, will change the 3rd position speed. But it's a $1200 gamble, and I've got other issues with the car right now that I need to spend that money on.......

Good luck!
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I have a bunch of these lower panels if anyone wants to buy one. I will sell the lower portion with the electronics much cheaper than what a new one costs....

 

Was a solution every found to this? It's a minor thing...but having A/C control options ranging wider from breathing on me lightly to Mach 6 would be nice.

 

I have never had any problems with 3. Usually mine is on 2, because 1 is too slow.