checkmate1996

I presume this will not work with the early models that are all vacuum based...

svpmx83

Manual vac/cable HVAC could be updated with the addition of vacuum control solenoids and a few other bits, and it should work on the late vehicles too.

As the project was never intended to be plug and play, there is a great deal of flexibility for someone with the determination to make it work.

yardpro

I am VERY interested.. especially at that price

svpmx83

Ok I have the control logic sorted and programmed

based on the VW system with some alterations that make sense to me.

AUTO - Automatic temperature, footwell vent and fan speed mode - Pressing the button "AUTO" overrides the following settings.
- Fan Speed becomes automatic
- Foot and Centre Vent are controlled automatically
- AC Compressor control is turned on (ECON MODE reset if active)
- Defrost vent remains open if manually set - and can be turned off by def button as a toggle

In ECON operation, only the compressor is switched off. Heating and Fan/Vent operation continues to be controlled electronically if previously on AUTO or manually if in manual mode.

DEFROST Mode I
- Fan Speed Set to 4
- Foot and Centre Vent remain at current setting
- AC Compressor control is turned on (ECON MODE reset if active)
- Defrost vent opens

DEFROST Mode II - Press and hold for > 1sec
- Fan Speed Set to 7
- Foot and Centre Vent Close
- AC Compressor control is turned on (ECON MODE reset if active)
- Defrost vent opens
- Rear Screen Heater turned on
*** MODE RESETS to DEFrost I after 20 minutes or ignition off

OFF Mode - Press and/or hold FAN Down
- Fan Speed Set to 0
- Vents remain as set
- AC Compressor turned off
- Rear Screen Heater turned off
- Heater Tap is closed

Available at all times
Manual selection of air recirculation mode
Temperature setting 18-29c with LO (max cool) and HI (max heat)
- LO and HI will set fan to 4 if in manual mode

Manual options (all will turn off AUTO)
- Manual fan speed selection OFF , 1-7
- Manual selection of air flow to instrument panel vents (if installed)
- Manual selection of air flow to footwell vents

selected settings remain stored in memory after switching the ignition off and will be recalled on subsequent re-start.
Only the functions "Air Recirculation" and "Defrost II" are erased on ignition off or after 20 minutes of use.


Heating A/C Logic:
If connected to Megasquirt and
- starting from cold - coolant temp is used to hold fan speed low until engine
warms
- Engine load and RPM used to disconnect AC Compressor clutch on acceleration

PHIL928

Wow, awesome job man!

svpmx83

To make this easy to follow - I'll keep updating the first post as it progesses

svpmx83

Circuitry all done and tested, will be testing and tuning in vehicle over the next week.

BigAl1

Awsome!

fbarnhill

It is indeed awsome and I need it. Mine the ***** keep falling off and you have to find just the right place to get things to work. Lucklly for me, everything works, it is just the control head that sucks.

svpmx83

Draft build information INCOMPLETE SO DO NOT USE YET

http://www.reanimotion.com/GPIO%20Hv...structions.htm

dprantl

I see some little grilles on that climate control unit. Would those happen to be for an interior temperature sensor? In which case, could that one be used instead of the existing 928 one at the top of the center console?

Dan
'91 928GT S/C 475hp/460lb.ft

BigAl1

svpmx83

Yes, the internal sensor in the head unit is being used rather than the 928 unit

Alan

There are various options on switch gear that can be used - personally I prefer rotary controls for primary functions and buttons with simple status indicators for secondary controls.

I think that Climatronic looks good but I don't like the general digital switch gear style that much

I am working towards an alternate implementation based on the below pictured head unit control:

Main point here is that there are many ways to skin the cat - but nothing is going to plug directly in unless someone spends a whole lot of time (like Hans is planning).

My ideas are:

Rotary Control for fan speed:
- fully variable (PWM controller) and stock resistor pack switched speed modes
- in the switched modes these also control the rear fan speed via relays/resistor pack (when rear is on).

Rotary Control for Vent Control:
- Primary - Console, Footwell, Defroster
- Secondary (intermediate positions) - Console+Footwell, Footwell+Defroster, Defroster+Console

Rotary Control for Front temp (with integrated max cool & max heat overides)

Rotary Control for Rear temp (flow) with integrated rear on/off switch

Buttons with indicators for AC (on/off), DEF (on/off) and Recirc (on/off)

I have plans to swap the console vent to full automatic operation (using an '83 dual level vac actuator - off, 1/2, full. I'll also swap to a '78 console vent with **** - but converted as an electric switch actuator to allow some manual overide of this same automatic console vent flow control.

I've also got a design for a water valve mod that ensures it maintains the last commanded mode (open/closed) on shutdown, and that will go in too.

Implementation will be sometime this year (hopefully) - though I have tested various features stand alone already . My goal is plug & play with easy reversion to the stock (HVAC head) - except for the consolve vent changes & water valve changes which will be compatible with eitherhead unit. I have all the parts needed for this - its just time that has been lacking, this one has been on the back burner for about 2 years now...

This head unit also has an internal sensor - but not sure if I'll use it or not (have not verified direct or adaptable compatibility).

I will document what I do on this but this will be a lot of work to adapt - including demo/fabrication and circuit construction.

I will dump most of this head unit's circuits for new much simpler design (mostly designed already).

Like Steve, I will not be offering anything here except my ideas and an example... given the scope of the other changes I will do - it will be difficult to replicate directly on another vehicle.

BTW I will try out some alternate 928 style ***** on this - not sure how that will work out - but I've done a few adaptations like this before and have some ideas of what to try.

Alan

Champagne

I feel obligated to jump in here.

Hans as worked really hard to design a replacement controller from scratch. And I came up with a simple but attractive fascia.
I'm sure most of you are aware of the project.

I'm just pointing out that our version is still in the works and should be ready shortly. I know a lot of you are waiting patiently.

Thanks

Paul