Sorry in advance for the length.

Background: We left the sunroof open in fall of 2020 for a few weeks. Discovered water in front footwells, rear carpet wet, and trunk area had standing water. Cleaned it all up and replaced the tailgate module with a knock off and bypassed a module in the MOST loop (I forget which one) due to issues. Battery also was replaced this year.

Lingering issues are occasionally we get a seatbelt warning for the passenger seat even without an occupant and there's a fault for interlock faulty on the shifter (which I may just replace). IHKA has a fault for no communication with condensation sensor and auto circulation sensor. Also occasionally while driving the HVAC screen will go dim/off and the fan will slow. But it immediately comes back. It's like a brown out or a running reset. And then it appears every module is reporting/has reported a K-CAN fault.

The other issue which may or may not be related, but is the point of this post, is the AC isn't functioning. Unfortunately I can't remember if it wasn't working the next summer, but it definitely was not the summer of 2022 (it's my wife's car and she teleworked all through COVID so it barely got driven). We just had it in the shop and they claim the AC clutch isn't engaging and is bad and therefore wants to replace the compressor + drier. I mentioned all the electrical gremlins and asked if they've verified electrical signal is good at the clutch and they just said it's definitely the compressor. AC was recharged in 2018, with dye, mechanic couldn't find a leak, and it held vacuum for an hour. I mentioned that to this shop so presumably pressures are good and not the reason the clutch wouldn't engage. Shop has great reviews but is my first experience with them.

We declined all work because with other issues the bill was $8600 (3k for compressor work). And I'm stubborn and feel like it's too much of a coincidence, so I'm not convinced it's actually the clutch itself. My theory all along is the K-CAN faults are impairing the signal to the clutch, possibly due to whatever handshaking needs to be done between IHKA and DME. There is no idle change when I try to turn AC on, nor do I hear the fan spool up.

I got ISTA installed and connected yesterday and I'm getting the same faults that my cheap scanner was picking up. But perusing the web it looks like most people get a fault for the coil going when the clutch goes, which I am not.

I'm thinking of this for a diagnostic path forward:
- Access the compressor connector and check for resistance. From what I gather it's a one pin connector, so just check resistance from there to engine block. Open means coil is fried.
- Jump 12V onto connector to see if I can get clutch to engage.
- Use ISTA or another tool to try to engage clutch through "normal" means but bypass any normal handshaking.
- If it is the clutch I'm going to pursue replacing only the clutch, although typically I'd be one to replace the compressor. We're a recent family of 4 and unfortunately are finding the X5 doesn't really suit our needs for family trips so just trying to get by until we find a replacement (and hopefully long enough for the market to calm down).

So in summary my real questions are:
- Can K-CAN issues cause AC issues or am I chasing ghosts?
- Is ISTA the right tool to try to "force" the AC clutch to engage? If not, what is? If it is, how? My only experience thus far is pulling codes, creating a test plan, and I did execute the one to relearn seat position. But as there are no faults relating to AC, I don't see a way for ISTA to do anything in that regard.
- Any recommendations on K-CAN troubleshooting? I did a visual inspection of the wiring before the rear fuse panel and looks ok, and intended to check for shorts to chassis and open between the modules back there but haven't gotten to it. I also did a visual inspection of the JBE.
- Best source for wiring diagrams?
- I jumped the gun and bought a junkyard IHKA. Worst case it's a fix for faded buttons and maybe will fix the brown out issue. But does it need to be coded? Googling seems to lead to no for E70, but yes on other cars.

Much appreciated!

__________________
'08 X5 4.8i - 196k
'15 i3 REX - 95k - Blown AC compressor

'98 323is - 170k - Garaged
'94 325i - 208k - Sold