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-   -   94 530i AC and re-circulation coming on randomly (http://www.bimmerfest.com/forums/showthread.php?t=651465)

manuelwindows 10-12-2012 02:45 PM

94 530i AC and re-circulation coming on randomly
 
So this just started happening. I'll try to describe it as best as I can.

The AC has always been kind of weak but it worked and when I did turn it on, it had a slight whistle but nothing big for something I was glad that even worked. So my AC worked but made a slight whistling noise.

My recirculation also worked and now I believe that they both work off the same fan that is different from the main heater blower fan because the heater blowers and front defrost blower work just fine and have normal power and heat.

The three buttons for the rear defrost, AC and recirc. are mounted in a column next to each other in this model, on the dash, kind of lower, in between the stick shift and the radio.

Last night, the LED lights behind the recirc. and AC started blinking and coming on intermittently, at random. I looked for a pattern in case it could be some kind of diagnostic code and it is basically at random. One thing is that sometimes the lights flash green and sometimes they flash yellow. It is like they are trying to tell me something but it all seems very random. I've looked through these forums and googled this a whole lot and I've gone through the fusebox in the engine compartment but I haven't pulled out the backseat to look at the one in there because, well, that's why I'm here, let me get to what I'd like to do.

I'd like to just disable the AC system and whatever fan this is that is coming on for the recirc and AC because when it comes on, there is just a very slight loss of power to the engine, barely noticeable, but it happens.

Ideally, I'd like to have the whole system working again but I live in a climate where I don't really need AC and it's about to be winter anyway and so what I'd like to do is just electrically or otherwise disable this little AC and circ. fan (or blower) that is cutting on and off when the lights blink.

And also the rear defroster, same thing, on that same column. I'd prefer that keep working but if I have to pull a relay that disables all three, that's fine.

I've also looked through Bentley's and my owner's manual on this and the specific issue on exactly which relays and fuses are which are not that great although it does say it on the box cover, the box cover is not that great with the diagrams for individual models and this differs often from year to year, model to model.

So if anybody has dealt with this or has a "clean" way for me to just disable this little AC fan or whatever it is, electrically or some other great suggestion, I would appreciate that. Thanks!

manuelwindows 10-12-2012 03:25 PM

Also, I just noticed, because somebody said I could disable the AC with the key in the number two position (between off and ignition, the position where you get all the lights to come on). When I put the key in position two, I sat there for about a minute and noticed that small fan / blower coming on at random again and the AC and recirc buttons were coming on green at random at the same time this little fan noise would come on.

I could not adjust that random thing in any way by pressing any of the buttons.

With the key there in number two position, the main blowers, the regular and more powerful ones for the front defroster and console would not turn on, which I think is what is supposed to happen because they need more power from the engine, which is not running in position number two.

manuelwindows 10-14-2012 02:32 PM

So I learned in another forum from multiple people experiencing the same symptoms and how they resolved it that this is mostly likely corrosion in the IHKR module located behind the panel there where the buttons are and probably some corrosion on that module. Which makes sense also because I live in a high-humidity environment. There's also a youtube video about how to pull the panel and locate the IHKR module to fix it. I can't post the link to the video cause it won't let me because I'm a new member. Anyway, the video scared me with all the wires and what-not and pulling a panel that doesn't want to be pulled and lots of scary wires. But I do know a BMW AC guy whom I trust and it sounds like I can get a new IKHR for about $40 so I am hoping to get this resolved for less than $100 and I can live with that. I will report back with the results.

By the way, I was able to just disable the buttons from flashing and the AC coming on intermittently by pulling the #27 fuse in the fusebox in the engine compartment, so that stopped the lights from blinking and the thing coming on and off while I get it resolved.

manuelwindows 10-17-2012 12:03 PM

I'm back from the AC guy. Here's what happened, of course. Like I mentioned above, I had pulled the #27 so that the AC would stop coming on intermittently and so that the lights would stop blinking while I got it resolved.

When I took it to the AC place, I showed the guy, the #27 fuse and put a new fuse in there so then he could see the problem.

After I put a new fuse in there, we went in the car so I could show him how it was blinking and coming on randomly and, voila! It was working just fine again. No blinking or coming on randomly.

I still think that the main problem is corrosion on the connectors that go to the AC module and expect to deal with this issue again but I am knocking on wood and hoping it was just that fuse but that doesn't quite make sense to me, electrically. What I did learn is on this model, it is easier to get to that AC module (the "IHKR brain") than I thought. You don't have to pull the center panel or any instrument panels. You just have to pull the radio (relatively easy) and then you remove the glove box (also relatively easy) and pull the side panel and carpeting next to the AC and heating instrument cluster. This is the panel to the left of the glovebox, to the left of where the passenger's legs would be and after pulling that panel, you can access the AC module, without pulling the console or disturbing the other wires. It's not attached to a "sword" like in some later models. I only found this out after sifting through the Bentley's manual I have on .pdf (waiting on hard copy) where it explains how to get to that AC module. Then, in preparation for possibly getting a new one, I learned that they go new on places like auto warehouse place for about $550, which was just not gonna happen. But I located a used AC module for this model on Bavarian Auto Recycling for about $50 and on eBay for about $100, if it does turn out I eventually need a new one, I'll be doing this myself. But first, I'll just pull that panel and clean off the connectors to the module to see if that works first. (if this comes up again) The manufacturer's part number for the AC module for this car (sometimes referred to in these forums as the "IHKR brain") is 6411-8-390 134 4

So I just thought I'd post this if anybody else runs into this issue, so it's up here.

Gremlins are another suspect.


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