Beginning of an Automatic Climate Control System, all juiced up on Fusion
Ok here's where I am at with automatic AC controls with the brain. I have a pretty good idea of how I'm going to take control of the blower with the brain, All of the dampers are pretty much no brainers (I have vacuum actuators for all of my mode doors, but my temperature door will be a servo-amp type like many other vehicles).
I haven't gone too far into where I'm going to put the sensors yet, as this is a conversion from a truck with manual AC controls, to some super-sweet automatic AC controls; so I'm gonna need some new sensors.
From the factory, my vehicle had a knob on the control unit that ported vacuum to each actuator (through some monsterous maze of ports inside). I found a mainfold that contains little 12V solenoids
Here's how it incorporates into the existing vacuum circuit. This is going to be an easy swap in for me. And it will work for anyone with a number of vacuum solenoids they need to operate with the brain.
The only door left to drive needs a servo-driver, it's much like the ones I've found in the skimmies for tons of other cars so, this may help you if your car only has electric servos as well.
There is more going on in the block than they're showing, for instance; the two leads going to the motor are not in and out, they are 12V and control, on this servo, control needs 2.5V to hold position, 0V closes, and 5V opens.
The return path (not really shown) is the top terminal. 5V reference is needed for the third terminal down, and the 2nd changes (position pot) as the servo moves, in the OEM automatic setup 0-5V is turned into 0-255 counts and used to compare with the desired position (I'll get into controls and alogrithms soon, just not right away)
I think I'd be safe using an analog out if greenman100 can make the values instantaneous like he wants to, there's virtually no draw on the control terminal. I have been playing around with 2 relays and 2 resistors as an alternative way of coming up with 0-2.5-5 volts as well.
that's pretty much it for the mechanics of temp control...Oh here's the servo I'm using.
I'm not going to go into how much I hate most of my alternatives. I want variable speed, and I'm not settling for 4 speeds or ten relays, Honda uses power transistors, hell even the version of my truck with auto control uses PWM, the big problem with that is it uses pwm to drive the motor AND a PWM control signal drives the driver, and I don't think we're quite up to PWM outputs yet so... I think I'm going with the power transistor style setup used by Honda, Jag, Audi, etc. What I've found appealing about those is they seem fit for using a low-power, analog control signal, and I get a feedback signal as well.
Here's some rough stuff that I've thrown together so far on this method.
That's pretty much all of the outputs and a couple inputs. I hope some of the more engineering savvy will help guide me with my circuits, keeping me from making too many rookie mistakes (the tech that I am).
I will make an initial placement decision on the temperature, humidity, and sunload sensors soon and post them as well.
A note on my sunload sensor, I need to see if the one already in my truck for my headlights is the one they use for the automatic AC system as well.
As for the temperature sensors, I'm sure that I am going to be poking at least one little hole in my airbox, ones going in the grill area, and one is going in the people-tank.
More to come soon...