No AC, K-CAN?

[Nanniepoo]

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!

[ard]

duplicate

[ard]

Just maybe an comment from the cheap seats... you have a 'flood car'. Basically this is the problem they get- over time corrosion leads to failures- could be a component that fails or could be corrosion in a contact that leads to intermittent, then failure.


I agree with your sense it is not a compressor- that something is causing the fan not to engage... Id really study the multiple schematics to really understand how that signal is controlled.


(as I recall: If the system was properly asserting the 'clutch engage' and was driving that line, then the DME should also cause the engine speed to change. It isnt the fan coming on that causes the engine to change- both are commanded. ie the idle should change but the clutch would not respond)



Also, a visual inspection is fine for a first past, but you will need to open each connector and burnish every contact, pin and socket to be sure.

GL!

[Attacking Mid]

Here's a thread where I solved my slew of K-can faults: https://www.bimmerfest.com/threads/k...#post-13736539

AM.

[Nanniepoo]

I played around with ISTA a bit more. Nothing earth shattering, but I think mildly interesting nonetheless.

In ISTA I commanded the JBE to activate the AC compressor. Nothing happened. I don't know if the clutch was indeed bad that this should trigger a fault for a bad coil or not in this state, but it didn't appear to.
Reading the state of AC values, it's saying not available.

Looking at IHKA states, it thinks it's calling for AC.

Looking at DME states, it doesn't think anyone is calling for AC.

So my understanding is the JBE is the link in all this, and it's not able to read or activate AC, and the link between DME and IHKA (which is the JBE) isn't working.

So path forward still seems to be troubleshoot K-CAN, but I'm also suspect of the JBE at this point.

[Nanniepoo]

Well...had an interesting Friday looking at the car.

No idea what the heck the shop was looking at. There are two compressors available for my car, which they definitely were aware of:
64529185145 which has a magnetic clutch
64529185144 which does not have a magnetic clutch.

They informed me mine had the magnetic clutch, and it was in fact the clutch that was bad, as it wasn't engaging. They also quoted recharge with R1234yf after replacement.

Got eyes on the compressor Friday, and the sticker on it is 64529185144, so NO MAGNETIC CLUTCH, and also states R134a. So they couldn't even figure out the right freon or compressor, and completely mis-diagnosed the issue since the compressor is visibly spinning all the time, as there is no clutch, so no idea how they concluded the clutch wasn't engaging, as logically if one was under the impression that there was a clutch, it looks like it's engaged permanently.

Played around with ISTA again, and I am able to activate the "compressor control valve" and hear it click. Obviously trying to activate compressor clutch, which I had been trying to do previously, did nothing as there is no clutch. And since I spent all day on it, I'm now seeing JBE reporting refrigerant pressure of 0 bar, so my guess right now is it just needs a recharge.

[ard]

Grrrrrhhhhh.


Many shops just shoot from the hip with a LARGE number- figuring 'why spend much time on a diagnosis- if this loser falls for a $3k guess, they can always report "well the compressor was bad, but wouldntcha know it- it took out X Y and Z, so another $2800 for those".



Its why when people take a car and are told "it is X", and then they buy an X and look for someone to install their X, it can be a world of pain... but you know ths/


If you just had a solid refridg service in 2018, AND they used dye, I would (1) not suspect its just normal leakage that a recharge will fix and (2) get someone with UV to look for that dye around fittings, compressor shaft, etc.


Those JBEs are diabolical.....doing a paredo of 'what might it be', a JBE is usually up there.



Does the TIS have a 'operation description' on how the AC system works/is controlled? If not a clutch, is it a variable output type? dunno, too lazy to look.


GL! (again)


Oh, Im reminded of a billboard from a local HVAC company ... Shows a silhouette of a curvy woman, hands up kinda holding her head.... it reads:




"Your wife is hot.....










.

SO FIX THE AC!!!!!"

[Nanniepoo]

Yeah I agree on the loss of pressure being too fast for normal. I'm taking it back to the same shop that did the original recharge and did put dye in, so I'll ask that they take a look.

[ard]

Did you inspect the issue that Attacking Mid had identified? Worth a look-see.

[Nanniepoo]

Other shop called back...they could not find any evidence of UV dye. And the system held vacuum as part of the machine's check before refilling. Said it's blowing cold and happy.