blackknight530i

Hmm, I'm not so sure about that. What you're describing sounds like a 3 way switch for a home lighting load, which works fine on AC power, but I've never heard of it on 12V DC power.

No matter what configuration of the wiring I do, the "Compressor Voltage" wire, which is the only one going to the compressor from the climate control unit, shows 12V. The other pin on the compressor is a black with gray stripe coming from the heater relay under the dash and is the same on both 987.1 and 987.2, which is a switched 12V when car is on, so it can't be what cycles the compressor on/off. The only thing that makes sense would be that the black with white stripe wire from the climate control unit is supposed to switch from 12v to ground when it "activates", then back to 12v when it "deactivates", but it is not doing that.

I did some more diagnosing today and am still no closer to getting it working, other than by connecting the climate control wire to a permanent ground, which seems to work fine, but may freeze the evaporator coils. When using the 2006 climate control unit, I get an error code for the outside air/recirc. flap motor, which does seem to be getting some clicking noises, though didn't have a problem before from what I recall. That is the only error code I'm getting though. Not sure if that would disable A/C or not, but I do get a CAN Shutdown = Yes status.

Using the 2009 climate control module, I get an error message for the NTC (evaporator temperature sensor) and the seat temperature sensors (since I don't have cooled seats). This is with it coded for "external" under A/C Compressor in PIWIS. The 2006 unit can't even be set to "external". If I program the 2009 unit to "internal" like the 2006 unit, I get an A/C Handling (implausible signal) error, but the NTC error goes away. Since the 2006 doesn't seem to use an evaporator temp sensor, I'm thinking the "internal" and "external" have something to do with this.

I've tried every combination I can think of with coding and moving the compressor voltage wire to the two different locations and nothing seems to make it work any differently, other than the error codes I get. I think the only thing to do at this point is to either try to wire in the NTC sensor to the existing wiring without removing the heater box, or replace the heater box entirely with the newer one and use the newer module. That is going to be a nightmare to do though as it requires pulling the entire upper dash, passenger air bag, and center tunnel frame. It also requires evacuating the R134a again and re-bleeding the coolant since the heater core has to come out as well. The good news is that since my current heater box is blowing foam at me from every vent, at least I could repair that properly at the same time.

Cemlo

After reading your latest findings I think you are nearly there. Sorry, did'nt want to confuse things, just trying to simplify things as in house wiring.

I think it's the following situation: "So to operate an XYZ the computer can either send 12 volts to the XYZ (switched 12V when car is on) which will then go to the ground, or it can ground the XYZ which already has it's own 12 volt supply.

"other than by connecting the climate control wire to a permanent ground" - to me this is what you are missing, a swiched to ground. The error messages, are there any modules/sensors causing them that are part of the circuit and could provide switched ground?

blackknight530i

Correct, but I'm getting 12v on both sides, which doesn't turn the compressor on. I would think it would either be an open circuit or ground, which is how most any other switch works. I can't even get the output from the climate control module to change when turning the A/C off button on or off. It's like I need to wire in my own on/off switch and put it in-line between the ground and the compressor signal, but that is not very elegant.

I think I'm going to try swapping the heater boxes since the later one has the hole for the evaporator temp sensor already, as well as a slightly different wire harness including that connector, plus it has good foam. I think I'm going to preventatively replace the foam on the flaps while I have it out of the car though so it doesn't fail like the one in my 2006 has. I just hope that by having the evaporator temp sensor hooked up that it allows the A/C compressor to turn on properly. I would test it by just adding the temp sensor to the existing wiring, but of course, they used a different type of connector and the pins don't fit.

blackknight530i

Ok, figured out the issue and also how to solve it, which is what I thought it would be. I decided to go ahead and test with the evaporator temp sensor wired in temporarily and used the 2009 climate control unit, coded for "external", which I found out is for the externally controlled variable displacement compressor that is used in the later cars, while "internal" is for the internally controlled variable displacement compressor used on the earlier cars. It works as expected. That means that if I swap the heater box or retrofit the evap temp sensor into my existing box and add in the wiring, it will work. Now, I guess that means I'll be swapping the whole box over because if it has to come out to retrofit the sensor, I may as well swap the whole thing, and it should fix the issue with the foam and the outside air flap motor failing.

The other thing this means is that I need to use the 2009+ climate control module, which doesn't fit in the center stack frame and is black instead of gray, so it also means I need to swap the button panel and pocket, along with the frame for the center stack. Not a huge deal though since the frame needs to come out to change the heater box anyways, but now I also need to see if I need to get a different aftermarket radio frame for the 987.2 center stack.

I feel like after this is all done, I'll have swapped nearly everything over but the main wiring harness, LOL. Again, super glad I had the whole donor car to figure all this out.

blackknight530i

So... this escalated quite quickly.




I was hoping to not have to strip apart another dash, but this is what was required to swap the heater box. This is all so I can add one sensor to the front of the heater box that isn't on the older car so the A/C will work properly. It did allow me to fix the spraying foam issue that plagues these cars, so that's good. We got it all taken apart yesterday and today will be putting the new one back in. I hope I remember where the nearly 100 T20 torx screws go, LOL. At least 99% of them are identical and I know where the other 1% go. I am truly amazed at just how many of them there are though and how hidden a lot of them are.

Zach L

Keep going!

I've been that deep into several interiors, but not a Porsche yet. How does it compare?

blackknight530i

We got most of dash put back together yesterday, but I think I'm sore in nearly every muscle, LOL. It takes a lot of contortion to get everything in there properly. Upper dash is in, but I found that you have to install it in a certain order. For example, you need to have the passenger airbag in place and plugged into the wiring harness, but not actually installed because there's a lip on the back of the upper dash that has to go over and behind it, yet the dash has to go in straight forward, so the airbag is in the way if it's installed. Of course, then there's the duct for the right side vent that is in the way of properly installing the airbag once the dash is in. We got it, but it's a pain.

We also go everything under the hood buttoned up. I only lost the amount of coolant in the heater core and a small amount from the hoses, so I think bleeding it should be simple enough. I even thought of pre-filling the heater core, but figured it wasn't really worth it.

As for how it compares to other cars, I've not gone quite that far into an interior before and had to re-install, but I have done plenty of dash swaps on e39 BMWs and I will say there are a ton more little t20 torx screws that hold the dash in than the BMWs. I can have a BMW e39upper dash out in probably an hour or two.

blackknight530i

The dash is all back together and now has the black 987.2 center stack modules since I needed the newer climate control module. I did have to change the wiring for the button panel below the climate control a bit. The newer button panel uses a 20 pin connector instead of the older 16 pin. Fortunately, the pins are identical, so I bought a 20 pin connector and housing on Ebay (still not interested in cutting up the main body harness from the .2) and swapped the pins over. They all go in the same numbered positions as they were in the 16 pin connector, but pay attention to what I said. The positions physically will change since 1 row goes from 1 to 10 instead of 1 to 8, so make sure you keep the numbers the same, not the "positions". The one change that needs to be made that is for the button panel, but at the PSM module. The PSM Off light wire needs to change from pin 46 on the PSM connector to pin 38 on the .2 PSM module. Why they needed to move this wire, I don't know. Everything still functions just fine, it's just the indicator light that tells you PSM is Off. PSM Off still shows on the dash.

I haven't reinstalled the panel on the driver side of the dash and the A-pillar yet because I'm still waiting for my power cord for my Valentine 1 hard wire kit to come in so I can route it up to the mirror location.

blackknight530i

Oh, and I also attached a fast wireless charging coil and circuit board with a 60W 12v to USB-C power adapter to the bottom of the cubby in front of the shifter. I wired it into the 12v power outlet above the Bose subwoofer and it works great! Now I can just slide my phone in like I normally do and it will wireless fast charge while connected wirelessly to the Pioneer head unit for Android Auto.

Lizard King

Holy cow that was a LOT of work you did to that car.

blackknight530i

Well, had the A/C recharged again last Friday and now the A/C is working perfectly. That leaves cruise control as the last thing that doesn't work on this car after the swap. Does anyone know if there is a tune that would disable cruise control? It's so weird because I'm not getting any codes for it and the green light comes on when turning cruise control on with the stalk, but none of the functions actually do anything. Tells me I didn't leave something unplugged or anything, but just curious why it doesn't work with the new DME. Unfortunately, I sold the steering control module from the donor car already, LOL. I don't really use cruise control anyways, but it would be nice to have everything function properly.

Also, got the coilovers switched over to the AST 5100s from the donor car and they seem to ride a lot nicer than the H&Rs based on an initial test drive.