93+ AC compressor question

[ShadowofBob]

Since my compressor just ate the dust(on my drive out to Colorado through the Nevada desert no less ) I've decided to try and fit a B4 climate control system into my Coupe. From what I've gathered the only thing that is hard to overcome is the fact that AC compressor on the Coupe doesn't have a speed sensor. The speed sensor is needed in order for the AC to run on the B4 climate control cars.

"Provides an A/C compressor speed signal; the A/C clutch control module (manually controlled A/C) or A/C control head (automatic climate control) compares A/C compressor speed to engine speed, calculates belt slippage (percentage) and switches the A/C compressor off if slippage is too large (if, for example, the belt is too loose)"

Since I can't use a 90 V-6 compressor I was wondering if anyone here knows if the B4 era S2's have the sensor on them. If they do I can just order one of those and use it to get the later model climate control to work. Is the compressor still on the right hand side on the RHD cars? If they don't have the sensor then do the climate control cars just not need the signal?

[Skull]

This klimatronic are some *******. The control units are somehow married with their own compressor. Me and some friends tried changing ECU-s in different B4 (also same engines), and some showed errors, some didn't). If your AC had the sensor on the compressor, you will absolutely need to have a compressor with it, to make it work. If you find a compressor that suits your engine type and has no sensor, u will have to take also the ECU, but im not 100% sure it will work with your wiring. Find one compressor with the sensor, if you have the V6 engine (I think in the USA there were only V6 engines available), look also for C4 compressors, the engines are the same.

[ShadowofBob]

That's the problem, the Coupes came with the 7A 20v engine in the USA for the two years they were sold here(90-91). The later model climate control systems are only found on the V-6 93-95 90s. The compressor shouldn't make a difference. If only provides an off switch for the clutch. The reason a newer on is needed is for the speed sensor. So do the 93+ 20v motors have compressors with this sensor?

[SCarGo02]

As I just posted a moment ago - the klimatronic unit can be coded for use with any engine - although according to ETKA only the 4/6 cyl B4s utilized the speed sensor - the 5 cylinders did not.

My Bentley repair manual for the 90 says that the coding for the head unit in US B4s should be set to 00062 (6 for 6-cyl and 2 for US) - I've been having problems with the clutch speed sensor on my '94 - so instead of tearing further into the AC system (which is working fine - just a wonky sensor and/or wiring) I've recoded it for a 5-cyl (00051 --- 00052 didn't seem to work - so maybe it knows the US didn't get 5-cyl cars). Either way the AC compressor now stays on and doesn't go right out like it used to - and the speed sensor code is now gone as well!.

[ShadowofBob]

Great news! Guess I can go ahead and buy the old style compressor and get my AC working until I can get ahold of the B4 climate system. How do you program the code into the klimatronic unit?

[S2central.net]

I'm with Skull on this - the compressor and the climate controller module have to be from the same system type AFAIK from what I've picked up on the subject so far.

Early LHD cars had the old style 1st generation 'klimatronic' system - as fitted to US spec CQ20V and other B3 family members. This has a certain type of controller and compressor - all of these work on R12 refridgerant AFAIK.

With the advent of the B4 came what I call the 2nd generation climate control system with its more modern looking control panel in the cockpit. This look was introduced circa 1992/1993 and was available across the 80/90/100/A6 models. Originally available as an R12 system but then transitioned to R134a for 1993/1994. This was only fitted to LHD B4 vehicles - the poor folks in the UK and other RHD territory have a manual control system with yet another type of compressor.

This same single channel system used on the B4 followed thru into the B5 platform of the Audi A4 but of course the electrical wiring looms are only compatible with that family.

I think if you can locate the compressor and controller from a V6 equipped B4 vehicle, probably with the aircon loom as well, then it would be possible to upgrade the system in your CQ20V... But I suspect there might be lots of integration issues with respect to air control valves, flaps and sensors unless by some fluke or intent that they are interoperable with each other.

Not for the faint hearted this stuff !

[SCarGo02]

Oh most definitely, you would need the rest of the setup from a B4 car to use the B4 climate control system, although you might be able to keep the AC system as-is. All I was saying is that the klimatronic system can be recoded work with a compressor without a clutch speed sensor.

[SCarGo02]

Great news! Guess I can go ahead and buy the old style compressor and get my AC working until I can get ahold of the B4 climate system. How do you program the code into the klimatronic unit?

On the B4 klimatronic you access it with VAG-COM and simply change the coding - takes all of 20 seconds to do!

[ShadowofBob]

Oh most definitely, you would need the rest of the setup from a B4 car to use the B4 climate control system, although you might be able to keep the AC system as-is. All I was saying is that the klimatronic system can be recoded work with a compressor without a clutch speed sensor.

Yea, I'd need the whole climate system. Can't use it with the Coupe's due to it using a vacuum based flap system. Know of anyone around in CO parting a 93-95 90 with the klimatronic system?

[SCarGo02]

I don't know of any private parties parting any B4s, although, there was a pick'n'pull yard off santa fe in Denver that had a '93 90CS a few months ago.

It's at Budget Auto in the pick'n'pull yard, not the other yard where they pull parts for you...Linky to them. On the same street is Adam's Import which is mostly Audi...not a pick'n'pull nor cheap, but they'll have everything you need.

BTW changing the head unit to a 5-cyl from a 6-cyl has disabled the speed sensor check and now that my car has a full charge of AC, I can confirm that it works!

[ShadowofBob]

Sorry to bump and old thread.
Are there multiple 5 cylinder settings? While looking at diagrams for a 1994 S4's climate system diagram I saw that it used the speed sensor.