ShadowofBob

Well I'm just about done putting in a B4 climate box in my Coupe. I found a B4 box at the junkyard and for 20$ I decided to grab it and start this project. Wiring was fairly easy and I made an adapter harness(3 plugs from the b4 box harness to the male connector of the b3 climate control head that was cut out) to plug into the existing climate harness. All I have left is to put the dash back in place. I did some testing tonight without the car running(need to put new bomb, hydraulic lines, and rebuilt AC compressor in) and everything looked good. Got readings from all temp sensors, the instrument cluster temp display worked, and the blower motor and electronic servos all functioned.



One thing that I noticed is odd is that if I set control to manual and temp at LO and max the fan speed it won't stay at max setting constantly, it will sometimes fluctuate down to mid level and then back up. The display shows it to on the level meter. Is there some reason for this like no engine power or is it something else?

I'll do a full write up with pictures and wiring info once I am finished and can confirm that everything is fully working. AC won't be confirmed until the spring.

Does anyone have the center console section of the dash from a B4 w/ auto climate control they'd like to donate or sell to me? The climate control unit won't mount into the B3 panel or a manual B4 one.

Jim Bush

snowman0650@excite dot com

Jim Bush
Holland, MI

Junker CQ

The fan is still getting a command from the "Auto" set-up sensor. You need to find a way to by-pass the sensor when you go to the "Manual" set. Maybe a a jumper by-pass wire. Send me your wiring schematic and I'll see if I can figure out a by-pass for you.

8Rings

I'm still going to use the stock, vacuum driven heater/ac box but I'm going to control all the vac motors with toggle switches.

duncanm

Nice...definitely interested in the write up

ShadowofBob

If it's a wiring issue then it would have to be in the blower assembly harness, but there isn't a manual or auto sensor. It's all done by the control unit. The adapter harness I made only sends over temp info, AC relay, and ecu info. The blower actually has done this from the time I first did a test run with just the 3 pin power, ground, and illumination plugged in so if it is anything it must be in the harness or the climate control head is faulty.

Even if it is still thinking it's in auto mode the climate unit is set on LO so it should have no trouble blowing on max setting because it's not trying to reach a set temperature. Unless Audi has a cut off point to try and keep people from freezing them selves. The interior and intake duct sensors all read high 40s low 50s. Outside temp sensor was at 39f.

How do you get error codes off the control unit? I know how to read the diagnostic channels, but can't figure out how to get the codes.

SCarGo02

What model is your head unit out of? Did you ever recode it?

ShadowofBob

Haven't recoded it yet, don't have the diagnostic port hooked up either so I'd need to plug it into another 90 or car with the late model climate control to get it recoded. The box is from a 1993 90 and the head is from a B4 90, not sure on the year. I thought recoding would just be necessary to get the AC working?

Junker CQ

The interior sensors tell the head unit when to cut off the blower fan. Apparently you have tapped into the wiring for it.

SCarGo02

...although I was more or less curious if the head was from a B4 or not as some seem to say a C4 head won't control a B4 box (although I tried over the summer and it seemed to work fine).