Climate control panel interchangeability

[Antsa]

Does anyone know if early a3/a4 climate controls can be fitted to our cars with the newer climatronic panel. My climatronic refuses to turn on the radiator fan even though it should. Before trying to pinpoint the fault inside the unit I thought I would try using a different control panel and I thought that maybe a newer/cheaper control panel can be used. I tried searching different forums but could not find definitive answer.

[diogocartier]

Does anybody knows that?

[mdz]

A4 has a sunlight sensor at the top of dashboard, 80 doesn't, but it has a second interior temperature sensor near interior light. I'm not sure how this affects the behavior of climate control, haven't tried the a4 unit.

[80Quattro]

Someone did post the details about the differences between units a few years back, but I don't think it was complete. I think you should be able to use the control unit from a MY95 A4 and it's either the same, or there are no differences which affect operation. I believe anything later won't work correctly.

[Antsa]

Thanks for the asnwers I've been trying to find the early A4 climatronic current flow diagrams to compare pinouts, but I haven't found them yet.

My problem is a little odd though. If I do the climatronic output test to the rad fan with VCDS, everything works as it should: the rad fan rotates on the lowest setting. So probably not an internal fault.

But when operating climatronic normally nothing happens with the rad fan. Previously it has always came on if the blower is on (no matter if the A/C activated or not).

This needs further investigation

[Roach]

Have a look at this if the link works https://www.scribd.com/document/2960...te-Control-Min

[johne]

Have a look at this if the link works https://www.scribd.com/document/2960...te-Control-Min

I wrote that! I assume someone has scraped it off the forum and is now asking for you to pay to see it

Anyway, it's a "Sticky" in this section under "Climate, what climate"

https://www.s2forum.com/forum/techni...te#post1118511

Climate control units ex A4s around 1996/97 will certainly work but I never did any investigations to prove units after 8D0 820 043 H work. I have the early A4 climate pinouts and they are essentially the same. When Audi added additional sensors over the years they tended to substitute a default value if the sensor wasn't there maintaining a good - but not infallible - degree of backwards compatibility.

If you read this thread - also a Sticky:

https://www.s2forum.com/forum/techni...into-rhd-avant

You'll see that the biggest problem with later controllers after 043 - H is that they won't control your vacuum operated recirculation flap.

The output from the controller to the 1st stage fan relay (J26) is pin D16 on the controller so when that goes low the radiator fan comes on and you could check that but since it works under VCDS, it's reasonable to assume, as you have, that the "problem" is inside the controller. I don't know what the algorithm is inside the controller for activating D16, certainly on the manual A/C system bringing on the heater fan brings on the radiator fan but in the climate system the algorithm may be more complicated and you're missing another input that's monitored in combination to activate the radiator fan.

An alternative would be to use the drive to the compressor to engage relay 3, J26 instead bypassing the controller but of course as soon as F23 High Pressure switch kicks in you'll get the radiator fan on at 2nd stage anyway.

[Antsa]

Big thanks johne for writing the pdf, it has been very helpful with all the pinouts and partnumbers