All Encompasing Car Computer Project. HVAC questions.

**mistareno** · 10-20-2011, 06:39 PM

Hello all,

I am about to start what will no doubt be a long, arduous and expensive journey into the world of Car Computers.

I'm probably taking the 'bite of more than you can chew and then chew like hell approach' as I intend for the touch screen to control the HVAC system and preform all the usual Infotainment duties aswell as digital gauges etc.

Whilst the Infotainment and gauge side of the system can be a work in progress, I really need to get the HVAC system sorted in theory and perhaps see a few examples before taking the plunge as I was intending on using a 12.1 16:9 inch touchscreen in portrait landscape built into the console area which will see the old hvac binned.

The HVAC air distribution in the car is predominately vacuum operated with the exception of the fan, heater tap and a/c thermostat which are cable driven.

The vacuum side of the system is an easy solution as I can run electric vacuum solenoids in place of the current buttons which I assume a Fusion Brain can handle easily as it is just an on/off deal.

With the heater, I was going to run a servo motor connected to a cable that operates the original tap (I'm not sure if FB can control a servo?) I was probably going to use something similar for the a/c thermostat.

I was hoping to use a pwm for the fan although I'm not sure if Fusion braing can handle that sort of current load?

Is Fusion Brain the way to go?

I am more than able to do the graphic side of things, but the programing side of things will be a learning curve.

I am happy to use a centrafuse front end or similar, but I'm not sure how it will look in portrait orientation?

I have search here quite a bit, but seem unable to find any examples of hvac systems operated by the car pc?

Can anyone point me to some examples or are they few and far between?

**soundman98** · 10-20-2011, 09:01 PM

being that no one else has said anything...

i have seen hvac controls discussed, but don't really remember anyone going through it all the way. from what i remember, you are on teh right track--i believe the fb can control servo's, and the other controls would work with it..

it might be better to make a post about this in the fusion brain area--they will def be able to go into more detail on the programming and usage then i can.

**JoezDog4** · 10-20-2011, 11:44 PM

well check this out.. http://www.mp3car.com/worklogs/14704...n-control.html
ive been trying to come up with an HVAC approach myself, looking forward to seeing what you come up with.

**mistareno** · 10-21-2011, 04:43 AM

Originally Posted by JoezDog4

well check this out.. http://www.mp3car.com/worklogs/14704...n-control.html
ive been trying to come up with an HVAC approach myself, looking forward to seeing what you come up with.

Holy crap, that is certainly the deep end and in a big way...

It might take a while to read all that stuff...

**Ryven** · 10-21-2011, 02:45 PM

Mickz is pretty amazing. I had envisioned my system going the same route. I tried to follow Mickz, but his engineering is so far beyond my meagre, self-taught understanding.

Unless he had seriously evolved past what I last saw, he used the OEM climate control board and simply controlled it through software he wrote

**mistareno** · 10-21-2011, 07:03 PM

Ok, I had a think about this and this may be the easiest hardware solution.

It is a 16 relay USB relay controller.

I can use 5 channels for fan speed control (using the factory rheostat)

I can use 4 channels for the solenoids connected to the vacuum distribution flaps.

That would leave 8 channels which I can use for the temp control.

4 for heat - I thought it may be easier (although a bit clunky) to use 4 small solenoids to control water flow.

1 open for low heat through to all 4 open for high heat. I could manually restrict the flow via jets to fine tune things.

2 for AC - low and high.

I would have a few left over which I thought I could program for favorites or a solar ventilator when out of the car?

It may be clunky but atleast it should work, just need to sort a pretty looking interface.

**Mickz** · 10-22-2011, 02:20 AM

Hi, good luck with the build. The relay board looks like it will do a good job. I’m sure you checked the current rating of the contacts; they look like 10A to 15A relays so it should be good to go. PWM would be elegant for the motor but with the relays available you could change that later (if at all) when you get the mechanical control side of thing sorted. The Board looks like it should only need a few simple commands via the com link to set or read relay status. Mechanical control of a HVAC has its challenges but at least it should be harder to blow the HVAC control if you have an OH S^@# moment. I must send that cheque to Ryven.