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It was fun while it lasted
2002 ML320, 2005 S430 4MATIC RIP, 2010 F150 Crew Cab
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11,130 Posts
Discussion Starter #1
Blower motor on the 2005 S430 was working sporadically, as of late, now it's not blowing at all. I suspect the regulator has died. But, I've read some cases where some chose to replace both the regulator and the blower motor at once. What are your thoughts? I leaning just replacing regulator right now.
 

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Registered
2002 S 430
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247 Posts
You are right on spot that the problem most likely is the regulator.
However, it is also frequently the case that the regulator burns out because the motor
has greater than normal mechanical resistance.
That is why all the shops recommend to change them together, replacing just one may be
a short term solution.
For most of other models these are not expensive, not the case for the Benz.
 

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Purple Moderator
99 ML430, 00 ML320, 05 E500 4matic Wagon
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21,749 Posts
Not sure about the W220, but I did the regulator only on the 2000 ML320 and it has been fine for months.
I know the W220 is a whole different animal, but I am just sharing my experience that the fine was not causing
the regulator to blow.
 

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It was fun while it lasted
2002 ML320, 2005 S430 4MATIC RIP, 2010 F150 Crew Cab
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11,130 Posts
Discussion Starter #4
The regulator cost is $29 and the blower motor is about $140. My understanding is it's common for the regulator to go because of excessive use of low fan speed on the a/c control.
 

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Registered
2002 S 430
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247 Posts
With that price range I would change the regulator with no hesitation, if the blower must go.
Not much luck with my S430, it would cost about 400 give and take, aftermarket parts. Genuine OM maybe twice as much.
 

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Premium Member
W220 2003 Update S500L, W204 2008 C220 CDI
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444 Posts
It seems the most common cause of blower regulator failure is corrosion but of course being electronic it is prone to a heap of other failure modes such as heat, vibration, old age etc. Running the blower on low speed or auto should not cause any additional failure risk as the regulator is a pulse width mode device and is very efficient.

Several DIYers have successfully repaired just the regulator.

See here.
http://w220.ee/Blower

Regards
Brian
 

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It was fun while it lasted
2002 ML320, 2005 S430 4MATIC RIP, 2010 F150 Crew Cab
Joined
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11,130 Posts
Discussion Starter #7
The part came in yesterday and I installed it this morning. Blower now works flawlessly. The new part had 2 capacitors where the old one had just 1.
 

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It was fun while it lasted
2002 ML320, 2005 S430 4MATIC RIP, 2010 F150 Crew Cab
Joined
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11,130 Posts
Discussion Starter #8
Blower motor not blowing again

It appears either I have a small short in the blower motor burning up the regulator OR the regulator is a POS Chinese part that has failed. Arrrrrg! I'm voting for the POS Chinese part.
 

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Registered
2001 S500 Sport
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354 Posts
This is why you should have taken the advice given above and swap both the blower and regulator. Now you have to pay for a second regulator in addition to the blower.
 

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It was fun while it lasted
2002 ML320, 2005 S430 4MATIC RIP, 2010 F150 Crew Cab
Joined
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11,130 Posts
Discussion Starter #10
This is why you should have taken the advice given above and swap both the blower and regulator. Now you have to pay for a second regulator in addition to the blower.
It was $25. Well worth the try since MOST times, it's only the regulator. Usually I win. This time, I lost. Oh well, blower motor time.
 

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2004 S430 4Matic & 2001 SLK320
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58 Posts
I did just the regulator, six months later the blower went out. Replaced the blower, a month or so after that the replacement regulator failed. Fortunately it was still under warranty and they replaced it with no hassle. If I had to do it again, I would do both at the same time. It is a major pain to get under that dash and do everything on your back.
 

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It was fun while it lasted
2002 ML320, 2005 S430 4MATIC RIP, 2010 F150 Crew Cab
Joined
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11,130 Posts
Discussion Starter #12
Okay. Here's what's going on now. I replaced the assembly with a new blower motor AND new regulator resistor. The vendor who sold me the chinese resistor agreed to send a new one. I installed new resistor with new blower motor and zilch, nada, no dice. It seems you can hear a humming noise in the general direction of regulator every once in a while. The fan spins freely. I unplugged power plug to resistor and am getting a little over 7 volts. So new resistor is getting power. On max fan, I need to know the following if anyone can tell me:

1. How many volts should be coming out of resistor to fan when a/c is on MAX? 7? I get nothing going out to fan which tells me regulator isn't any good.

2. What ohms should a new blower motor/ good blower test?

I'm strongly suspecting the vendor is sourcing me bad resistors. I can't seem to find a new Behr or Bosch resistor. Only used ones which is what I had. I checked with an OEM vendor here and their catalog says part no longer available.

Thanks!
 

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It was fun while it lasted
2002 ML320, 2005 S430 4MATIC RIP, 2010 F150 Crew Cab
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11,130 Posts
Discussion Starter #14
You have got to be @&$?!# kidding me!

So, I ordered a new, OEM Behr regulator. As to not waste anymore time like last time, I decided to test it first. As confirmed, with air on max and with my glasses on, the power plug when testing brown with red is 12V. So, I have power coming from plug. I plug it in regulator, turn fan on high and ZERO volts coming out of regulator! Brand new out of the box Behr! This is unf$&@#%! believeable.

Pic of the POS:
 

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Premium Member
W220 2003 Update S500L, W204 2008 C220 CDI
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444 Posts
Try measuring the voltage going in to the regulator when there is zero coming out?
 

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It was fun while it lasted
2002 ML320, 2005 S430 4MATIC RIP, 2010 F150 Crew Cab
Joined
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11,130 Posts
Discussion Starter #16
Try measuring the voltage going in to the regulator when there is zero coming out?
Yes. I also tested the small green striped wire against ground and as my wife cut the air up and down, the voltage went up and down as it should. I'm going to even try to tighten pins in plug in case firm contact isn't being made. I bench tested blower motor. It's good as gold. The only common denominator between the motor and the power plug is this damned regulator.
 

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It was fun while it lasted
2002 ML320, 2005 S430 4MATIC RIP, 2010 F150 Crew Cab
Joined
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11,130 Posts
Discussion Starter #17
Test results measuring back of power plug

The regulator on the left is the chinese knock off and the one on right is the new Behr-Hella. I placed voltage meter probes in the back of pins on power in and found 12.5 v. As soon as I plugged it in the chinese knock off, it went down to zero volts measuring from the back of power plug. Turning a/c up and down had no effect. As soon as I unplugged it, the power on back of pins returned to 12.5 v. I tested the Behr same way. As soon as I plugged it in, it went down to 5.5 volts from back of plug. It only went down to 4.5 volts on minimum blow. I know these readings are obviously suspect but I can't seem to find a knowledgeable person here or any info detailing what these readings should be. Regardless of readings from back of power plug pins, I still get zero volts out of the blower motor pins. With plug removed from regulator, I test the signal wire from a/c controller (green striped) to brown ground, I get the following readings:
Max setting: 7- 7.2 volts
6 bars: 5.5-6 volts
5 bars: 5 volts
4 bars: 4.5 volts
3 bars: 4 volts
Min: appears to be about 3.5 volts.
 

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Registered
2001 S500 Sport
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354 Posts
OK, but did you plug in the new unit to see if it did the trick after you tested it? I'm pretty sure the system needs to be under some load in order for it to kick on. Also, try resetting all of the stored coded in the control unit as well. This is not a W123 that you can just freely probe and find the problem, these systems are controlled by hardware/software which work on a different level.
 

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Premium Member
W220 2003 Update S500L, W204 2008 C220 CDI
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444 Posts
It looks to me that you have an issue with the 12V supply line to the regulator. The supply line shouldn't drop to zero or a very low voltage when you load it up, ie try to draw heaps of current to run the blower.
My next step would be to identify where the regulator supply line originates (maybe at a fuse or junction point) and measure the voltage at that point with and without the blower. It should stay close to 12V.
You have all the symptoms of a dry solder joint, damaged wire or corroded connection (connector?) in the supply line. All of these will produce 12V on no load but fail under heavy load.
The signal wire from the ACC controller seems to be doing the right thing.

Later note: I decided to find the circuit diagram and see where the regulator supply line comes from.
IMHO it looks like the main culprit could be the blower fuse connector (X64/1) which is located in the engine compartment. If this had a poor or corroded connection it would produce the symptoms described.
Following the circuit back is pin 2 on the Right Front Fuse and Relay Module (K40/7 and I would try measuring the voltage here with and without the load. It should be +12V.
Next in the supply line is the blower fuse f33 which should also be +12V.

The relevant diagrams and locations of these parts are now in my documentation here.
http://w220.ee/WIS_83.40_Automatic_Climate_Control_(ACC)_or_Heating_Ventilation_and_Air_Conditioning_(HVAC)#Blower_Motor_.28A32m1.29
 

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It was fun while it lasted
2002 ML320, 2005 S430 4MATIC RIP, 2010 F150 Crew Cab
Joined
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11,130 Posts
Discussion Starter #20
OK, but did you plug in the new unit to see if it did the trick after you tested it? I'm pretty sure the system needs to be under some load in order for it to kick on. Also, try resetting all of the stored coded in the control unit as well. This is not a W123 that you can just freely probe and find the problem, these systems are controlled by hardware/software which work on a different level.
The unit does not work with the blower. I installed it anyway to test that theory. No go.
 
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