My blower and CCU hate me!

[BullKatX5]

Long time searcher, first time poster. I'm at a loss here and have been Googling and searching this forum (and the bimmerfest.com forums) for a long... long time. This problem is going on in my 2001 E53 (4.4l).

In a nutshell: my climate control unit is not working (no lights or controls), and my blower is always running full blast - even without the key in the ignition. I've pulled fuse 64 so the blower doesn't kill my battery. Additionally, and this may or may not be related, but without the CCU and blower there is still hot air blowing in the foot wells. The heat in the foot wells gets hotter as the engine gets hotter (we're talking melting-my-shoes-on-long-distance-drives-in-the-summer hot).

All of these issues happened at the same moment: I parked my car, went to turn down my heater and BAM! The climate control part of the module went full blast and could not be changed, and the blower went crazy. Turned the car off then back on "just in case" and the module was dead (blower still going this whole time). I pulled the fuse and... now I am where I am.

Possible solutions I've already tried:
- Replaced FSR this past winter (had overnight battery drain and some erratic heat issues; FSR replacement solved these problems)
- Checked all fuses related to the A/C and blower units/systems - no blown fuses
- Replaced the climate control module (this needed to be done anyway because the screen was busted)
- No errors on the OBD reader

Any other suggestions as to what I could check? Could the new FSR be defective (and is there a way I can test it)? I want to try as many potentially simple solutions before I spend more money on another FSR...

TIA

[crystalworks]

Was the replacement FSR and OEM one or an aftermarket part?

[BullKatX5]

Aftermarket

[crystalworks]

Then it's a definite possibility that it failed already unfortunately. Especially if a brand like Uro or the like. Many of us prefer OEM stuff when it comes to electrics (sensors, modules, etc) because of this.

Not saying it's what happened, just that it's a definite possibility.

[BullKatX5]

Ah ok. It was apparently a THG that, after a quick Google on the brand, I guess is known to go out after a few months. Is it common for the FSR to cause the CCU to power down? Some threads weren't specific on this...most referred to the FSR replacement as fixing the blower issue.

[X53Jay4.8is]

Originally Posted by crystalworks

Then it's a definite possibility that it failed already unfortunately. Especially if a brand like Uro or the like. Many of us prefer OEM stuff when it comes to electrics (sensors, modules, etc) because of this.

Not saying it's what happened, just that it's a definite possibility.

Oh yes stick to OEM electronic parts upon replacement.

[TiAgX5]

I had 2 aftermarket FSRs fail in 6 months (in 2005), got them from Deutsch Parts (e-bay).

The Genuine BMW FSR has lasted over 5 yrs.

[Qsilver7]

Regarding the IHKA (you referred to it as the CCU)...was it a new or used unit...and did you have the IHKA coded (especially if the part number was different or it came from an e39, or if was configured differently than the original (REST or MAX button)?

Although it mentions the e38 in the info below...the e38, e39 & e53 share the same HVAC design architecture (even though the IHKA panels are slightly different)...the underlying operational functions are very similar. Sometimes swapping in a new IHKA will work flawlessly, but if there's anything different...like a different software number...the IHKA will need to be coded. You can also hook up to BMW diagnostics (or some of the aftermarket software) and pull the fault codes from the IHKA. As you can see in the info below...it was designed with an EEPROM to be able to store not only memory but fault codes. So if there's an issue with the IHKA (CCU)...a simple diagnostic check up would highlight any faults.

[BullKatX5]

Thanks for all your help guys! I took out the aftermarket FSR and threw in a new genuine BMW FSR and BAM! everything is working as it should. I had no idea that one part could impact so much!