Climate into RHD avant

[S2central.net]

Clutch relay is J44 - controlled by pin D8 - on the Euro S2/RS2 CCU right thru to your 98/99 A4 model...

The MY98 US Bentley schematic shows F23 and F118 combined as one module but doesn't call it F129 like the UK schematic from Ben.

F118 is also used on S2/RS2 manual aircon - same switch - it connects to J153 as the clutch control relay. You know where to find it OK on the S2 loom ?

[rj scotty]

It's not as bad as it looks but yes dash out is a scary sight. Give me a shout when you ready to do yours.

cheers

rich

[S2central.net]

From 05/99 the US schematics show it as F129 - but functionally it all looks the same here... Do you want me to provide a blow by blow pin for pin description of what you should be looking at when the late A4 head unit is attached to an S2 ?

[rj scotty]

Yes do it !

cheers

rich

[rj scotty]

Still dint get the high pressure switch on that A4 diagram. it just closes J101 and tells the auto box

[S2central.net]

Look at F129 on tracks 24/25 of your A4 schematic...

The normally closed switch with br/ws and br/bl into C2 is actually F118.

Now look at track 26 on S2 manual aircon schematic B76 - see how F118 is wired differently via sw/gn and sw/ge via T5g and A85k respectively - you have to look at the wiring carefully in order to see some subtle differences in how this is done so you can convert properly.

12V feed into F118 on manual system comes via A85k terminal at J11 when aircon is switched on... unless you hard wire the 'hot side' of F118 to the 12V x contact then it doesn't present any voltage into CCU on pin C2 whether the switch is open or closed.

Hope that makes sense... I'll make a quick go at pin by pin analysis to help finalise the conversion - at least as another pair of eyes to help check your progress - I love this stuff - much easier to debug with hands on though

[S2central.net]

Lets do this one sheet at a time wrt the A4 schematics you have and the 5-cyl B3/B4 schematics... All attached here for the avoidance of doubt.

[S2central.net]

First off the logic for fan control is a little different between B5 and B3/B4 (lets just call it S2 for quickness). The B5 is cleaner actually but lets not worry about this.

J26 is relay for speed 1
J101 is speed 2
J135 is speed 3 (not used on B5)

Sheet B76/2 has a mistake with J26 shown in position 11 - that should be J101

On the S2 -
speed 1 is engaged by afterrun pump or aircon switched on
speed 2 is engaged by high temp switch F18 or when refridgerant pressure is too high (F23)
speed 3 is engaged by high temp switch F54

On the B5, things are more or less the same except for control wiring where F23, F18 and F54 switch the 0V path thru the relays - not the 12V side. For this reason we can ignore the radfan wiring and leave it as is on the S2 scheme.

Note that F23 is actually the normally open side of F129 shown on the B5 diagram on track 24.

I am over simpllifying this bit to cut to the chase...

[rj scotty]

This is as I understand it so far, keep it comming

[S2central.net]

Now lets look at Sheet 3 on the B5 diagram... There are a few wires here that are of note for the conversion into S2...

Track 14 - that sw/bl wire will go to the fusebox for X-contact... use terminal J75al on the S2 fusebox for this (as per B75/4 Track 51)... This will use the B5 ACC loom to extend the X-contact to numerous other parts of the loom (V2, F118 and J44)

Track 15 - that sw/ro wire will go to the fusebox for switched 12V (T15)... you could use J75al again actually for convenience, but if you already have it wired to another fused & switched feed then OK... only thing is it needs to be 30A fuse as this one is for blower motor - so J75al is good as you should see 30A fuse in position S17 already.

I think you already have the blower wired up... the B5 climate system will be wired to a 5 or 6-pin block at J126 via pins C11, C14, C16 and 0V... I think there is a 2-pin extension from this to the existing blower motor (V2) in the S2 evaporator housing.

[S2central.net]

One last thing on Sheet 3 - Track 21 and pin D16... this is used on the B5 for fan control... when climate switched on, this goes to 0V and activates speed 1... because the wiring logic for fans is different we can ignore this one as the S2 curiously uses signalling to ECU and afterrun pump so as to run the fan when aircon switched on. Hold that thought, but ignore pin D16 - Do not fit.

While we are here - one important plug on the donor B5 loom is T10p - supposedly a grey 10 pin block at or near the fusebox - this is a number of pins that will be convenient to graft into the S2.

[S2central.net]

Oh before we finish Sheet 3 - Pins D14 and D15 will have big dirty obvious earth straps - thats an easy one....

[S2central.net]

Sheet 4 then and the mysterious F129... The normally closed section of this switch is F118 in old money - shown as br/bl and br/ws on Track 25.

F118 is already on your car and it just needs spliced into the B5 loom as follows.

1 - At the S2 fusebox you need to find the sw/ge wire on Track 17 (B76/2) and DISCONNECT it from A85k

2 - Take that sw/ge wire and attach it to T10p/10 as shown on Track 25 of the B5 sheet - should be a sw/bl wire

3 - Then find the sw/gn wire at T5g/4 on the S2 - this is the other side of F118 - connect it to B5 plug T10p/6 where it meets the br/bl wire into C2


While talking about this T10p plug... the tidiest way to do this is with a matching plug - if you send me part number of plug on the B5 loom I can source t'other side and matching pins... or you can simply chop off Audi plug and use aftermarket male/female multipin jobbies

[S2central.net]

Only other thing of note on Sheet 4 is pin B1 which should connect to your ambient temp display - achieved via T10e/10 on the S2 loom on a br/ge wire

[S2central.net]

Sheet 5 is pretty much exclusive to donor climate loom with the exception of two pins for ECU signalling...

A2 is a sw/ge wire on T10/6 - a brown blug if you have it on the donor loom - connect this to T5h/2 on the S2 (or T10e/2) where it should land on pin 41 of the ECU and pin 3 of the afterrun relay to signal that aircon is turned on... This in turn is used by afterrun relay on the manual system to turn on the fan to speed #1... Looking at S2 climate loom it is curious that CCU pin D16 is also used for this function so you can wire that up to terminal K4 in the S2 fusebox if you wish. Bit of an odd one that... makes me want to buzz that out on the S2 to be 100% sure.

C12 is the sw/gr wire on donor plug T10/8 - connect this to T5h/1 on the S2 where it extends to the ECU on pin 6.