Faulty Climate Control - Page 2 - BMW Forum - BimmerWerkz.com
3-Series (E46, E90) Chat relating to the BMW 3-Series from 1999 to Current. Models include: BMW 316i, BMW 318i, BMW 318Ci, BMW 320i, BMW 323i, BMW 325i, BMW 330i, BMW 328 Ci, BMW 328i, BMW 325i/xi, BMW 330Ci, BMW 320d, BMW 330d, BMW 335d.

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#16 (permalink) Old 07-25-2004, 02:28 PM
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I think we may have found the most likely cause of the intermittent blower motor problem. That is very good.

LPM technology is a fairly new technology. Basically, if you have discrete blower settings such as OFF-1-2-3-4-5 or OFF-LOW-MED-HIGH type of settings on you blower controller, chances are you have 'old' technology or resistor-relay combination. If the blower knob has many more indents or if you can dial it at any position you want, you have LPM type controller.

We just started using LPM couple of years ago on high end SUVs because they tend to be little more pricey but probably much lower than you would expect.

Now, don't tease me with stinky A/C . . .
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#17 (permalink) Old 07-25-2004, 05:14 PM
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oooohhhh, enlighten us on stinky A.C please!!!

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#18 (permalink) Old 07-25-2004, 07:17 PM
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Quote:
Originally posted by Dirty_Tool@Jul 25 2004, 05:54 PM
oooohhhh, enlighten us on stinky A.C please!!!
You play dirty, Mr. D-Tool!

Why some A/C system goes "stinky"

Stinky, or as my kids refer to as 'socky', odour is caused by fungi living on your evaporator core.

This fungi thrives in warm moist environment (like inside of your shoes). Ever wonder whay stinky A/C smells like sock that has not been washed for a while?

When you turn on A/C in hot weather, for faster cabin cooling the climate system or the user selects 'Recirculate' mode or 'MAX A/C' mode. MAX A/C actually puts the climate control system in recirculate mode.

Recirculate mode closes the door that allows fresh air into the car. Where does the air supply come from? From inside the cabin! So what you are doing is recycling the stale air inside the car over and over. However, in doing so, you are taking the same air and circulating it through the evaporator core (the heat exchanger that cools the air) over and over to achive faster cooling.

Now, you are only supposed to use recirculate mode for about 10~15 minutes until the cabin is at comfortable temperature. Then you should select regular A/C mode to allow fresh air in.

After a while, does your feet feel somewhat comfortable? A/C must be doing its job of getting some cool air into your shoes (if you wearing one). What would happen to fungus that loves to make that odour in your shoes. You have circulated it all over the car. Now, whether you use fresh air mode or recirculate mode, you cannot avoid this. Eventually, some of this fungus would make its way into the A/C system. So that's the major source of the 'socky' fungus.

How does it grow? The evaporator core inside the A/C system cools the air moving through it. Air warm moist air passes through the evaporator core, the temperature drops. Say the incoming air is about 30C (about 80F). The outgoing air from evaporator would be about 5C (about 40F). The air at 5C cannot hold as much moisture as the air at 30 so it must release it as DEW on to evaporator fin surface. So the water collects on the surface of evaporator. This is discharged through a drain as long as blower motor is moving the air through evap core.

So you say evaporator is self cleaning? Why yes, it is! That is, if you use it properly. When you arrive at your destination, what do you do with your A/C system? Do you just shut it off? I think most people do. Evaporator is not complete dry! It is still wet! Then you leave the car in hot sun for hours for 'socky' fungus to manifest and nurture its young! The fungus will, given time and repetition, attach itself to the evaporator. Then, whenever the climate is most (hot humid days), when you get into the car, you immediately smell what seems to be old laundry. Mystery solved.

The smell is caused by personal hygiene, nature, and poor A/C knowledge. So how do we overcome this?

Forget personal hygiene. Let yourself go. You cannot avoid this.

Forget nature. It gets hot in summer. What can you do. Move to outer space?

So that leaves A/C knowledge. But before we get to that, I'll describe what is sometimes done to the evaporator to reduce the odour. Most evaporators (at least the ones used by our company) have fungicide or anti-bacterial coating as well as coatings and designs to flush out the water as easily as possible, ie. make the environment as unhabitable to the fungus/bacteria as possible. So solutions are there but nothing lasts forever. The coating/fungicide/biocide will eventually become ineffective by repeated usage and crud that accumulates on evaporator surface (dust, hair, oil, you name it).

The fun part. What can you do to prevent/reduce the odour? Follow these simple steps.

1. Turn OFF your A/C about 3 minutes before you arrive but keep the blower in highest setting. This dries your evaporator. Use recirculate mode as this recirculates cooler, drier air inside > which will dry the evaporator faster that fresh (?) outside air.

That's it. The point is to dry the evaporator core (which is full of moisture) and bring it above DEW POINT, ie. about same temperature as ambient. That's all you need to do every time you turn the engine off.

If you A/C already smells foul, you cannot completely get rid of all of your fungus. You can replace/clean your evaporator core + A/C case but that gets pretty expensive. However, if you keep your system dry when the engine is off, I am certain that the odour level can be reduced. After all, fungus cannot grow where there is no moisture . . .
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#19 (permalink) Old 07-26-2004, 04:06 AM
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I had that problem with my A/C recently and luckily it was still under warranty. I took it back to my dealer who changed the resistor...sounds like you have the same problem
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#20 (permalink) Old 07-26-2004, 06:08 AM
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thanks for all the comments guys ... GRD you know your onions

Also GRD - To answer your questions above ...

1 - No
2 - It does this regardless of temp/sun conditions. rain or shine .. its still tempremental.
3 - no its very random
4 - blasts on full then receeds slightly then stops.
5 - not checked fuse ... i ashume if fuse was knackered then it wouldn't work atall ?

q - do these sytems have a relay ? could it be the temp sensor behind the grill on the unit in car ? how can i test it ?

Kill Fox - - am i correct in thinking that the outer temp sensor is for the readout on my dash and doesn't have any links with the climate system !?!? or am i wrong ?

i've also enquired about buying a new Final Stage - they're only 50, are they easy to fit ? or does it get a bit tricky ?!

thanks for all the comments .. much appreciated

Dave
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#21 (permalink) Old 07-26-2004, 09:17 PM
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Some people just dont get it ........

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#22 (permalink) Old 07-26-2004, 10:31 PM
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According to your answers to my questions, I think it would be either the 'Final Stage' and/or motor.

Case 1: Motor commutator is packed (short) and drawing excessive current. We are talking about 2~5 times the usual current draw (40~100Amps). In this case, 'Final Stage' is most likely programmed to shutdown (fire hazard!). 'Final Stage' may be programmed to restart the motor after some time. In this case, replacing the faulty motor will solve your problem.

Case 2: 'Final Stage' electronics are fried or faulty, causing 'Final Stage' to overheat. In this case, 'Final Stage' may be programmed to shut itself down. It may be programmed to restart itself after some time. In this case, replacing the 'Final Stage' will solve your problem. Replacing it is not difficult. Couple of screws and couple of connectors should do it. However, getting access to it would be more difficult.

Case 3: Case 1 + Case 2. Replace both 'Final Stage' and blower motor.

If you want to check any of the thermistors (temperature sensors), hook up multimeter and measure resistance across the terminals. If the resistance changes when you hold the thermistor 'bulb' in your hand, than that is a pretty good sign that it is working.
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#23 (permalink) Old 07-28-2004, 04:22 AM
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thanks for the info GRD ...great stuff

Dirty tool - I do get it .. i just like to ask questions :P

remember the old chinese proverb - he who asks is a fool for 5 minutes ... he who does not ... remains a fool foorever
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#24 (permalink) Old 07-28-2004, 09:11 PM
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#25 (permalink) Old 07-29-2004, 08:49 AM
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I just bought a 320d 2001 BM 110000 miles, just started showing the same problem. My initial though was worn out carbon brushes on the motor. Any thoughts? How do I get to the motor and the LPM?

I hope to have a go at it this evening. By the way I am an electronics engineer with oscillosope, soldering iron etc, but no circuit diagram for the LPM and climate control board to follow. If any one out there can get hold of these then I can advise on which component to change rather than a whole board change.


RAZ
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#26 (permalink) Old 07-29-2004, 07:17 PM
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razak, if you go back to page 1, Dirty Tool has included a link showing how to remove the trim below the HVAC motor.

Blower motor brushes are typically design to last about 4000+ hours of usage. That is 1 hour of use, everyday, for more than 10 years.

If you have 2001 model, you still would have plenty of brush left.

You don't need circuit diagram to figure out LPM-Motor connection. It is very simple.

LPM typically has 3 inputs: input signal, +ve, and ground. LPM should have 2 outputs going directly to the motor: +ve and ground. LPM receives square wave from the controller (can be both rising or trailing edge activated), then translates it into a voltage. The voltage increases linearly with the shape of the square input wave, and hence 'Linear Power Module'.

LPM is a black box typically screwed to the HVAC case with couple of screws. It has large set of heat sink inside the HVAC case (either matrix of pins or rows of plates) Taking it out is little more tougher than changing batteries in kid's toys.
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#27 (permalink) Old 07-30-2004, 12:50 AM
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Just replaced my Final Stage today! With the help of this thread and a Bentley Manual, I saved about $200!

-J

<span style='color:blue'>2000 323i Sport Wagon (yeah, I got the wagon!)
Remus Sport Exhaust w/ Ralley Tips
Smoked Clears
10&quot; Kappa Perfect 10.1
1000w Kenwood Amp</span>
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#28 (permalink) Old 07-30-2004, 06:28 AM
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...thats a pretty informative and detailed lecture on fungus automotive habitat!
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#29 (permalink) Old 07-30-2004, 08:17 AM
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Hi, while I have been looking for a cure for a AC problem I have, (hot air at feet and head whatever the setting, cold out of face vents)?!? I have come across a lot of problems like yours, I think the cure is in the link below,it may only cost you 50 pence and some time to fix. Somebody is flogging the info on ebay for a tenner, it is just the same!!
Here it is: http://www.macadamizer.com/bmwfix.html
and
http://www.gbnetwork.co.uk/bmw/climatecontrolrepair.html (this site gives you some more info.)
Good luck
p.s. anybody know what my problem could be, I have seen it posted on a few forums but no answers
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#30 (permalink) Old 07-30-2004, 08:32 PM
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Archaicangel, congratulations!

Well, coupetouring, this is what you most likely have.

In manual control cars, you typically have 3 controls: temperature, mode, and blower speed. Mode is where you select

Defrost (windshield) > Defrost/Floor > Floor > Floor/Vent > Vent

Frankly, I do not know exactly how BMW climate control works. Anyways, 'actuators' are used to change the modes by rotating vanes/valves/doors to direct the air to various outlets. Actuators could be vacuum or electrical (sometimes even manual levers in economy cars)

From you description, it seems that your mode selection circuit is damaged. This could be:

1. Your climate control head 'Mode' knob could be faulty > not sending the signal to the actuator. This is quite possible.

2. Control head circuit is faulty. ie, it is mode change receiving direction from the knob or button, but output signal is not being sent. This is highly unlikely.

3. Wireharness is faulty. Well, open circuit, no power/signal, no response. Also not likely.

4. Dead actuator. ie. signal is going from input knob/button to control circuit, through wire harness, but when it gets to actuator > no one is listening. This is quite possible. Depending on where the actuator is located, it could be easy or messy.

5. Stuck door/valve/vanes. Everything is working fine but the moving mechanism is somehow stuck in the position (dirt, glue, broken, etc.) This is also likely. This one is nasty. Only way to fix this one is to remove the entire HVAC module, take it apart, remove defective component, replace with new component.
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