Z4 Blower/AC not working

[toddhunter]

Hello,

It is summer here in Houston and getting hot out. My blower fan/AC on my 2008 Z4 3.0i are not working properly.

The blower fan only runs at the speed of the first 2 notches. If I turn the rotary dial past 2 the fan does not run any faster. Also the AC does not engage, the snowflake does not light up and the AC does not get cold.

After researching here on the forum I thought it was the Blower Motor Resistor. I replace the part but the new one made absolutely no difference. I also check the AC system is pressurized by connecting a set of gauges.

My other thought was the car was in Transport Mode. I dropped by the dealer and they want me to bring it on for a full diagnostic costing several hundred dollars.

I dont mind taking it to the dealer but car is running great and I dont really want to pay for a full diagnostic and have them tell it was nothing more that resetting the Transport mode.

Is there a way to tell if the car is in Transport Mode?

I prefer to repair my cars on my own when possible, been doing that for 50 years. I am looking for ideas on what I can check further or how to handle this?

Thanks,

Todd

[Pelican Parts]

Hi Todd - take a look at the link below for the Blower Motor Replacement procedure. Please let us know if you have any questions!

http://www.pelicanparts.com/techarti...eplacement.htm

[bmwdirtracer]

Welcome to the forum, Todd.

It's likely that you have two separate issues...or, at least, you need to treat it that way.

When you hooked up the gauges, what were the high and low side values? I do not know your experience level, but it's the relationship between those two values that's crucial to diagnosis. The readings need to be done with the engine and A/C on. Are you sure that there's the correct amount of R134 in the system? (That's really the starting point)

As for the blower speeds, certainly, the FSR would be the most likely suspect. Assuming you replaced that part with a quality OEM part, I'd next suspect the Control module, rather than the blower motor, even though you have a "manual" system.("Manual" doesn't mean what it used to....)

If you want to do your own diagnoses, on an '08 car, you're going to need to be able to converse with all the computers in your car, with a good BMW specific diagnostic scan tool.

[rocket64]

If you really want to see whats going on with car, get a inpa cable and download inpa. All the info can be found on this forum. http://www.bimmerforums.com/forum/sh...xperimentation All you need is a computer running windows and a cable ($20). I found that the gentlemen on this site are very helpful.

[toddhunter]

Thanks for the input guys.

Yes I replaced the FSR. I got the part from AutoZone because they had it next day. I was surprised when the part I got had the EXACT same parts sticker as the one I removed and was labeled BMW Denso Bosch. The only way I could keep them separate was due to some light aging on the heat sinks of the used unit. So either AutoZone got an OEM part, or my unit had been replaced previously and the new one matched the previous replacement.

In any case I swapped the 2 units in and out a couple times and they both did the same thing, speed 1 & 2 only, no faster.

AC showed roughly 100 psi on both high and low sides as I recall. I think I mentioned that the compressor is Not kicking in, which is part of the problem. The fan blower runs on the 2 lowest speeds but nothing faster and the AC/Snowflake button does not engage and hence no cold air.

Rocket64 - reading the link you sent it seems to reference 2006 and older BMWs and Z3s. Will this work on my 2008 Z4? More than happy to invest in some diagnostic readers and tools, want to make sure I get the right stuff though.

[bmwdirtracer]

Todd, you need to wait for 328 Power 04 to answer your last question, regarding whether INPA will work for you. I'll ask him to check in on this thread.

Um, I really have to say that I've never, ever seen "BMW Denso Bosch" on any part. To the best of my knowledge, Bosch and Denso have no relationship. (I've been wrong before)

Interestingly, while FCP Euro usually has OE and OEM parts, the only FSR they offer for your car is the Genuine BMW part:
https://www.fcpeuro.com/BMW-parts/Z4...age%20resistor

I believe you are going to need some serious diagnostics, with the aid of wiring diagrams and top-level diagnostic computer, to find the issue at hand.
You've got an "Integrated Supply Module" involved in turning on the compressor, too. You really won't be able to diag this, I don't expect, without serious diagnostic software.


All that said, check fuses 22,24, 39, 57, and 61.

[328 Power 04]

Yes INPA works on Z4 (it's not limited to Z3, it was made for all 96+ BMW, until current). You would need a cable called "INPA K+DCAN" for your car; which communicates with the car with CANBUS system (all 2007+ BMWs)

But if you do decide to take that route, I would have to edit the INPA menu for you, as it can hold only about 15 models on the main menu screen. Not hard to do, just something that needs to be done to add the E85 chassis to the menu.

INPA would offer code reading and very few behavior activation for the IHKA module (climate control). It may or may not tell your problem directly, but it will read the error codes for it just fine.

If you're in the north side of Houston, maybe I can scan it for you.