3 knob HVAC control upgrade
01-09-2016, 05:02 PM
#91
Thread Starter
Yesterday at 4:02PM, I had a revelation! I'll come back to that in a moment.... The V2 boards arrived as a nice Christmas present for me, and with my holidays, got some solid time in the garage working on these. I assembled 2 units, one 2007-2009 style ***** and the other with 2010-2012 ***** (on the bottom in this pic). The older style unit is wired to work on 1980-1983 cars, and the other will be for late 83-95, to be used as my testers in house. The board design has a couple flaws, but nothing that can't be worked around for testing. I just got back in from the garage, and happy boy right now - I can control the vacuum relays with the Mode **** on my control - that works as planned!!! I have some airflow logic coded now, mostly copying the Nissan logic I'm used to, but that can be easily changed with a few lines of code. Next to test will be the PWM fan control, and with the new blower motor (thanks Roger!) and my Altima PWM fan amp (to be used for testing), I hope to show that Fan **** works also. A little bit of coding to do for that, and I'll head back out there to give it a try. Last will be the Temp control **** - need to test that and see how it controls the HVAC setting motor.
I started designing the facia for this, basically copying the geometry of the stock unit, but with the rotary ***** - note that only the 2007-2009 style ***** will be used for this as the 2010-2012 ***** are too large in the diameter to fit in the space available. But, I will use the newer ***** for kits that are mounting in my 2X DIN flush bracket and deleting the warning strip - similar to the pic at the start of this thread.
One of the flaws on the V2 board is there is no "OFF" capability, so I have 2 more design iterations since those boards, trying to add in that functionality. I got it, but now am having to make trade-off's with the number of pins available on the Nano chip, so started looking for other ways to control relays, but with only 1 or 2 wires from the Nano. The other problem all along is the plane orientation of the board eliminates the option of just plugging the car harness straight to the unit - that is why I have been making pigtails with a copy of the stock board connector at the end. There is no space to plug in the stock harness connectors on the edge of this board. These led to my revelation......
I'm now working on a V3 design that moves all the high current items off the main board with the *****, hopefully eliminating a source of electronic noise that could be tough to find for me. All the big power stuff will be on a daughter board, and luckily it will be the same plane as the stock unit, and allow me to setup a edge connector just like stock - no more pigtail hassles, and more polished look. Another part of my thought process happened at the same time - not everybody will want to cut a PWM fan amp into their airbox near the fan and modify wiring to bypass the resistor pack - some will want direct plug and play - no fuss, no muss. So, thinking about how to simulate the stock fan speed switch but with digital controls, forced me to look to how many outputs I have available on the Nano, and this led to the other things. Now I have a solution, except for the actual connector on the stock unit that the fan wiring connector plugs into - that could be a challenge to recreate. That may have to be short pigtails that plug into the heavy black connector - like Rob Edwards did for his center console mod.
Anyway, lots of things happening here. Every chance I get is focussed on some aspect of this project, and learning as I go!
I started designing the facia for this, basically copying the geometry of the stock unit, but with the rotary ***** - note that only the 2007-2009 style ***** will be used for this as the 2010-2012 ***** are too large in the diameter to fit in the space available. But, I will use the newer ***** for kits that are mounting in my 2X DIN flush bracket and deleting the warning strip - similar to the pic at the start of this thread.
One of the flaws on the V2 board is there is no "OFF" capability, so I have 2 more design iterations since those boards, trying to add in that functionality. I got it, but now am having to make trade-off's with the number of pins available on the Nano chip, so started looking for other ways to control relays, but with only 1 or 2 wires from the Nano. The other problem all along is the plane orientation of the board eliminates the option of just plugging the car harness straight to the unit - that is why I have been making pigtails with a copy of the stock board connector at the end. There is no space to plug in the stock harness connectors on the edge of this board. These led to my revelation......
I'm now working on a V3 design that moves all the high current items off the main board with the *****, hopefully eliminating a source of electronic noise that could be tough to find for me. All the big power stuff will be on a daughter board, and luckily it will be the same plane as the stock unit, and allow me to setup a edge connector just like stock - no more pigtail hassles, and more polished look. Another part of my thought process happened at the same time - not everybody will want to cut a PWM fan amp into their airbox near the fan and modify wiring to bypass the resistor pack - some will want direct plug and play - no fuss, no muss. So, thinking about how to simulate the stock fan speed switch but with digital controls, forced me to look to how many outputs I have available on the Nano, and this led to the other things. Now I have a solution, except for the actual connector on the stock unit that the fan wiring connector plugs into - that could be a challenge to recreate. That may have to be short pigtails that plug into the heavy black connector - like Rob Edwards did for his center console mod.
Anyway, lots of things happening here. Every chance I get is focussed on some aspect of this project, and learning as I go!
Great update!
01-12-2016, 09:30 PM
#98
Al, could you give me some dimensions for it or will it straight fit in the place of current hvac?
This week I will have someone make me a plate so I can fit my pioneer head unit/nav.
Thanks
This week I will have someone make me a plate so I can fit my pioneer head unit/nav.
Thanks
01-12-2016, 11:32 PM
#99
Thread Starter
The size will be a direct replacement for the stock head unit, same mounting, same fascia appearance. Warning strip will remain, but with the AC button (if you have it) removed and that hole plugged.
01-13-2016, 10:03 AM
#101
Thread Starter
The RH center button (normally used for rear defrost) will be used to manually turn on rear AC. The icon looks like air moving at the rear window, so is the best choice working with these *****. Not sure yet how the fan speed will be controlled - set speed or PWM variable. If PWM, then a fan amp will be required and I don't know where to locate that in a rear AC unit - never had one apart myself. It could be mounted in the main front blower duct, but will require some wiring to be routed from the front blower area to the rear AC blower motor - not an easy task. Set speed will probably be the easiest. I'll see If I can make it 2 speeds available in my hardware.
01-13-2016, 10:06 AM
#102
Rennlist Member
Excellent work Al!
It is coming along nicely, I can't wait to see the final product. My hat comes off to your ingenuity and skills.
My control ***** are sitting on the desk eagerly awaiting the arrival
Cheers!
Carl
It is coming along nicely, I can't wait to see the final product. My hat comes off to your ingenuity and skills.
My control ***** are sitting on the desk eagerly awaiting the arrival
Cheers!
Carl
01-13-2016, 06:08 PM
#103
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Fascinating effort! So the "PWM Variable" would allow far more fan settings than the four or whatever in the original configuration? Seems like a nice upgrade, I personally like having that on my Honda, seems much more modern.
01-13-2016, 09:24 PM
#104
Thread Starter
That's correct Tom. The newest board design on screen will support both the original style 4 fan speeds as the easiest install unit (plug and play), plus the PWM fan speed with a range of 24 steps between the Low and Hi positions. The PWM setup requires installing a PWM fan amp into the airstream just after the blower fan to keep it cool, and some wiring to connect it.
01-13-2016, 09:58 PM
#105
Rennlist Member
The RH center button (normally used for rear defrost) will be used to manually turn on rear AC. The icon looks like air moving at the rear window, so is the best choice working with these *****. Not sure yet how the fan speed will be controlled - set speed or PWM variable. If PWM, then a fan amp will be required and I don't know where to locate that in a rear AC unit - never had one apart myself. It could be mounted in the main front blower duct, but will require some wiring to be routed from the front blower area to the rear AC blower motor - not an easy task. Set speed will probably be the easiest. I'll see If I can make it 2 speeds available in my hardware.
I find the rear fan a bit noisy, and again..in the end, when the rear works "too well" (pulls in too much heat to the AC system) the quality of the more needed front AC unit diminishes at the same time.