Rear aircon temperature control in the front?

[Tony x]

Hi,
I'm hoping to interrupt the lead that goes from the rear aircons temperature control slider to the servo that operates the temperature flap so I can adjust the temperature from the front of the Bongo. The controls are the servo / electric ones, not the manual ones.
I'm not after anything fancy, a switch that turns the heat up to maximum or down to minimum would do just nicely.
Has anyone done this or can anyone shed light on what might be involved?

I'm only guessing but I imagine the slider is some sort of variable resistor in which case I could wire it to a switch that will switch in different value resistors.

It's a bit of an oversight I fancy that Mazda didn't do this given you can control everything else on the rear aircon from the front.
Maybe they know something I don't...

[mikeonb4c]

Hi,
I'm hoping to interrupt the lead that goes from the rear aircons temperature control slider to the servo that operates the temperature flap so I can adjust the temperature from the front of the Bongo. The controls are the servo / electric ones, not the manual ones.

I'm not after anything fancy, a switch that turns the heat up to maximum or down to minimum would do just nicely.

Has anyone done this or can anyone shed light on what might be involved?

I'm only guessing but I imagine the slider is some sort of variable resistor in which case I could wire it to a switch that will switch in different value resistors.

It's a bit of an oversight I fancy that Mazda didn't do this given you can control everything else on the rear aircon from the front.
Maybe they know something I don't...

Yes it is a (minor) design oversight I reckon. I have a mechanical system and handle the problem by leaving the slider to HOT in winter months and cold in summer months, with blower set to middling and vents set to face. I then just use the ON/OFF switch in the front cab to make the rear unit effective (e.g. switch it from min heat to max heat) . Seems better than nowt

[Tony x]

Cheers for the reply Mike.
The more I think about this, the more I think it is probably quite easy to do.

I suspect the rear slider control is a potentiometer with ground at one end, a positive supply at the other and a take off point where the slider is positioned.

I should be able to cut the positive supply and take off point and run them to a double pole, double throw switch with two poles (the control off position) running back to where I cut the wires and the other two poles (the control on position) connected to a rotary potentiometer which I'll put underneath the heater controls in the front. The final ground wire wont need to be switchable and can just run from the end of the front potentiometer to the end of the rear potentiometer.

It all sounds a bit complicated written down but, in short, for around £10 and a couple of hours work, I should be able to get full and proportional control of the rear temperature control in the front of the cab. Another hour or so would get it all looking good with maybe labels and LED indicators.

You'd have a switch that switches control from rear to front and a rotary knob that will adjust the temperature.

If it all works out, I'll post again with diagrams and a how to do it description.

[mikeonb4c]

Cheers for the reply Mike.
The more I think about this, the more I think it is probably quite easy to do.

I suspect the rear slider control is a potentiometer with ground at one end, a positive supply at the other and a take off point where the slider is positioned.

I should be able to cut the positive supply and take off point and run them to a double pole, double throw switch with two poles (the control off position) running back to where I cut the wires and the other two poles (the control on position) connected to a rotary potentiometer which I'll put underneath the heater controls in the front. The final ground wire wont need to be switchable and can just run from the end of the front potentiometer to the end of the rear potentiometer.

It all sounds a bit complicated written down but, in short, for around £10 and a couple of hours work, I should be able to get full and proportional control of the rear temperature control in the front of the cab. Another hour or so would get it all looking good with maybe labels and LED indicators.

You'd have a switch that switches control from rear to front and a rotary knob that will adjust the temperature.

If it all works out, I'll post again with diagrams and a how to do it description.

Sounds like a really interesting mod. Look forward to hearing how it goes. Good luck and keep us posted

[Tony x]

Well...it works!
And it's not too difficult to do (although I made mistakes so you don't have too)

Here's what to do..

1) Remove the large panel that holds the rear heater controls so you can get behind it.
2) Unplug the connector that goes into it.
3) Remove the cup holder thing from the panel (one screw then slide rearwards and up)
4) Remove the two screws that hold the heater control panel in place.

The heater control panel should now be free to take where ever you want.

5) Pull off the knob that is the temperature control slider
6) Invert the control panel and remove all the screws (5 or 6 I think)
7) On the sides of the control unit are 4 clips. Unclip these and separate the control unit halves.

You should now be able to pull the circuit board out.

On the business side of the circuit board, connect a wire (the pink one) as per photo below





9) Strip away the plastic on the outer wire of the ribbon connector to expose the wire and cut it
10) Connect a wire to each end. I used a brown wire for the circuit board end and a blue wire for the end that goes to the servo.

You now need to secure the wires and file a bit of a gap where the two halves of the heater control join so the three wires can exit.

The black wire shown in the photos isn't needed although might be if you want full proportional control.

If you join the brown and blue wire, the heater is controlled in the rear as normal
If you disconnect them, the heater turns itself to the fully hot position
If you connect the blue wire to the pink one, the heater goes to the fully cold position.

Now route all thee wires to the front of the Bongo, either up and through the headlining or through the engine bay and under the drivers step.

Finally, add a switch or switches.

Below are some ways to wire switches up. the last one being a simple 3 position switch, the first being all singing and dancing with led indicators that dim if you turn the lights on..

[g8dhe]

Nice one Tony x, worth being made a sticky I think, or at least a do not delete!

[mikeonb4c]

Excellent sounding modification. Just too bad mines the old mechanical system. I'll have to rig up something using string and pulleys

[Tony x]

I've finally got the controls sorted. It took a while as I wanted touch controls rather than latching switches so I had to wait for some little circuits from China.

Being an ergonomist by training if not by trade I put the switch that gives you rear control in the front under the Mazda heater controls rear button and the temp' control button under the Mazda temp' control switch:-

All off:-



Cold:-



Hot:-



The LED's dim when the lights come on, power drain is minimal...happy now

[Bob]

Nice one.

[the1andonly]

absolutely surpurb. expect to see it cloned.
Touch sensitive switches? been looking but easier to ask can't any thing like yours.
The unit is it easy to move?

[the1andonly]

confusion abounds

[Tony x]

The aircon unit comes out easily and a bit like a radio. Either remove the instrument console cover and radio to push the metal tabs on the side of it to allow it to pull out or remove the little plastic covers on each side of the unit (Long vertical strips on far left and right) that then expose slots you can put a knife into to push the tabs down (although I struggled here)
The place I put the push button switches in was full of injection moulding gunk and was difficult to clean up. The plastic is thick and room is tight.
The circuit I used to get the push buttons to operate were these:-
http://www.ebay.co.uk/itm/281809563021? ... EBIDX%3AIT
The buttons were these:-
http://www.ebay.co.uk/itm/251779585322? ... EBIDX%3AIT
And the LEDs were:-
http://www.ebay.co.uk/itm/161807662918? ... EBIDX%3AIT
You have to extend the buttons by chopping the end off one and sticking it on another otherwise they wont reach the front panel - like I say, space is tight

[tommyb43]

I think this is an old post but fantastic information and a Great Find
Do you have any more information and updates on its life or future problems to expect ?

This is a mod which i was working on until i found this post, I was looking at putting
momentary switches onto the heat actuator which would do the same job i think.
comments or criticism would be appreciated.

[g8dhe]

The actuators are like model radio control actuators the position is sensed by the potentiometer and is a feedback loop to the electronics, so simply pulsing power to the motor will initially work but will then return to its original position to match the input control within a second or so! You need to alter the input control voltage to cause the system to drive to the new position, its normally a Pulse Width Modulated (PWM) system which minimises wiring requirements (a single wire per motor).