Automatic AC to RHD

[S2central.net]

@Acidburn - yes please document with as many photos and part numbers as you can to help me, Jamo and others.

The actual head unit can come from LHD RS2 (like the one I got) or similar year 100/s4/s6 - the head unit needs to be coded a particular way as the compressor on the S2/RS2 does NOT provide a speed signal to the head unit. I'm not 100% sure if the A4 head unit can be coded to work in this way - it might not be an official code - but it might work. I'd have to hit my books on this - I started collecting info at home on this.

[S2central.net]

One thing I cannot remember is if the RHD B5 (Early Audi A4) climate harness will work on the RHD B3/B4 conversion... I sort of figure it should - maybe with some mods so it hooks into B3/B4 fusebox. Other alternative is climate loom from LHS RS2 - it should be easy to mirror that for RHD operation.

It actually wouldn't be hard to build a custom loom for this anyway - all the connectors would be available individually.

[Skull]

That is why we need an A4 b5 blowerbox, to check the number of flaps, position of flaps, sensors... it is very likely that the differences are just cosmetic, just the plastic box of a different shape.

[S2central.net]

We know for fact the B5 blower box (from RHD A4 with climate) works... Johne used it for his RHD climate install on his S2... By some monumental fluke - the RHD B5 blower box connects to RHD B3/B4 centre box.

On RHD cars the climate doesn't use all of the flaps - there is one not used for some reason - can't recall which.

One other thing to do on the RHD conversion is run wires up to front interior light switch where the roof temp sensor resides on LHD B3/B4... This could be relocated to upper section of dashboard perhaps to save the 'fun' of installing those new cables up the A-pillar and under roof trim.

[Skull]

We know for fact the B5 blower box (from RHD A4 with climate) works... Johne used it for his RHD climate install on his S2... By some monumental fluke - the RHD B5 blower box connects to RHD B3/B4 centre box.

On RHD cars the climate doesn't use all of the flaps - there is one not used for some reason - can't recall which.

One other thing to do on the RHD conversion is run wires up to front interior light switch where the roof temp sensor resides on LHD B3/B4... This could be relocated to upper section of dashboard perhaps to save the 'fun' of installing those new cables up the A-pillar and under roof trim.

installing that A-pillars wires is the easiest job od them all. For the automatic AC there is another sensor that must be mounted on top of the dash.

[johne]

installing that A-pillars wires is the easiest job od them all. For the automatic AC there is another sensor that must be mounted on top of the dash.

It's the sunlight sensor, but whether you need it depends on the exact number of your climate computer and it's software version. A4's have it but I don't believe LHD S2/RS2s did.

I fitted it inside my screen outlet vent grille whilst I had the dashboard out.

John

[johne]

We know for fact the B5 blower box (from RHD A4 with climate) works... Johne used it for his RHD climate install on his S2... By some monumental fluke - the RHD B5 blower box connects to RHD B3/B4 centre box.

On RHD cars the climate doesn't use all of the flaps - there is one not used for some reason - can't recall which.

To avoid any confusion over which box is being called the "blower box", the box with the fan motor in and the box in the passenger footwell with the aircon evaporator in it stay just the same as fitted to manual S2 cars with A/C. It's the centre box with the heater matrix in it that has to change to one that has motor driven flaps. You can't use the unit from LHD RS2s (except maybe as a source of motors/flaps) because the air inlet is on the wrong side.

@Skull is suggesting you can motorise the centre box from a car with manual A/C replacing the bowden cables & rotary knobs with the motors and flaps from a climate LHD car. I'm not sure about this as I started with a late S2 that had no aircon fitted at all and my original centre box was different.

As Paul says, I used the centre box with heater matrix from an early climate RHD A4 and took the chance it would fit - which it did.

I'm not sure about a unit from 100/S4. An early 100 I worked on had a very different unit with vacuum controls and was fitted and removed via the engine compartment and would be no use to us. Later 100s may be different, I just don't know.

The motor not used is the air flow flap motor, V71, so you only need 3 motors, the recir. flap being actuated by a solenoid and vacuum motor.

John

[johne]

One other thing to do on the RHD conversion is run wires up to front interior light switch where the roof temp sensor resides on LHD B3/B4... This could be relocated to upper section of dashboard perhaps to save the 'fun' of installing those new cables up the A-pillar and under roof trim.

On the US cars fitted with the early climate controlled by vacuum motors and the climate computer with the row of buttons, the interior temperature sensor was installed behind the slot you can see in the housing at the top of the windscreen with sunroof control and interior light switch. Audi were too lazy to do away with the slots so we have them but no sensor and no wiring. This is a crap place to put the temperature sensor anyway which is why on the LHD S2/RS2 with climate Audi moved the sensor and there was an assembly underneath the top of the dashboard with a pump to draw air from above the dashboard by the screen vent down over a temperature sensor.

This still isn't ideal so on A4s the sensor was moved to the front of the dashboard about where the S2/RS2 central air outlet is, still with a pump to draw air in from that point and over a sensor to measure the temperature. On later Audis, the air is actually taken in at the climate computer face panel.

Bottom line is that to get the system to work the best you need the interior temperature sensor mounted around the height of the radio on the front of the dashboard. I chose to modify one of the blank switches - I don't have heated seats - and put the temperature sensor there with the pump for drawing in air behind. I can post a picture if anyone's interested but not now as I'm nowhere near my car.

John

[S2central.net]

Yes - V71 sounds familiar. Thanks for clarifying the 'blower box terminology'... Its the centre box that is of interest.

When I talk about the early 100/S4/S6 system - I mean the digital single channel system - not any of the vacuum controlled nonsense.

[Skull]

The problem is i am only talking about th LHD box. I only know hot this one is made. it is a 3 piece, i have also opened a thread with pics about it.

First piece, the one that has the fan inside. it has 2 flaps. one moved with an el. motor, the other moved by vacuum (recirc. flap).

Center piece, with the aircon radiator. no flaps, but one big temp sensor, red box.

Third piece. 3 plaps. all moved with el. motors. up/down flap (legs/face), cold/warm flap, and the third flap, that blocks the air from going to the vents in the dash.

So 5 flaps, 4 el. motors, one vacuum lever.

[johne]

Yes - V71 sounds familiar. Thanks for clarifying the 'blower box terminology'... Its the centre box that is of interest.

When I talk about the early 100/S4/S6 system - I mean the digital single channel system - not any of the vacuum controlled nonsense.

The bit that worried me with the vacuum 100 central heater unit was that it fitted from the engine bay, had an integral fan motor after the a/c evaporator which was in the scuttle and was a very different beast, physically, so unless the later cars changed construction substantially to be like B3 & A4 cars, the unit would be very different and no use to us.

The common key here could be the heater matrix. The heater matrix for 80s and early A4s is the same so any RHD model with climate control & that heater matrix could be a potential donor?

John

[Acidburn]

Don't need all that loom

[Acidburn]

We know for fact the B5 blower box (from RHD A4 with climate) works... Johne used it for his RHD climate install on his S2... By some monumental fluke - the RHD B5 blower box connects to RHD B3/B4 centre box.

One other thing to do on the RHD conversion is run wires up to front interior light switch where the roof temp sensor resides on LHD B3/B4... This could be relocated to upper section of dashboard perhaps to save the 'fun' of installing those new cables up the A-pillar and under roof trim.

On the wiring I picked up this is a sensor in the vent on the dash from what I can tell.

Bottom line is that to get the system to work the best you need the interior temperature sensor mounted around the height of the radio on the front of the dashboard. I chose to modify one of the blank switches - I don't have heated seats - and put the temperature sensor there with the pump for drawing in air behind. I can post a picture if anyone's interested but not now as I'm nowhere near my car.

John

Can you get some pictures of this please just for reference

[Error404]

This is an interesting thread, i'd never have remotely considered retrofitting A/C into my coupe until now, but for digital climate it might just be worth the effort.

[Acidburn]

It would be if you can get everything cheap enough and all from the same source etc.