More PIX...

Finals comments: I believe the former owner must have replaced the regulator since it's a BEHR made in France and had thermal paste applied sloppily all over the place. I recommend using bare minimum. Notice how some paste was over applied to the bottom heatsink with no contact to the blower housing thus acting as an insulator.

If this lasts a few years, I'll be happy vs. $399...the amount of air being moved in the passenger cabin is like a sh*t storm...WOW...no need to block off the back and passenger side vents anymore to get airflow.

This repair is an extremely welcome need in my part of the woods!

Best of luck,
Mo

 

I forgot, you'll also need a 13mm wrench for the battery terminal and radio code to unlock the secuirty feature...

 

where might one obtain this code

 

nice... my air flow is weak too... This will definitely save me a couple hundred dollars. Thank you.

 

Well, the eBay source Hamburg Technic regulator failed 100% and left me with absolutely no airflow during stop and go on the highway, 105F yesterday. Sucked big time so I ordered a KAE version from Autohaus...

The eBay source is offering to send a replacement but I'm not so sure anymore about these no name fan regulators. $75 makes it too attractive...(*&^&$@

My old BEHR still works but low speed is all it's got...

 

Hi MOS500,
Thanks a million for the pics and process notes. I need to replace my blower regulator, too. I already replaced the In-Dash control module for the Heater/AC... still no fan response - so blower regulator is next step.

I was also going to pickup the parts on eBay. Are you sure, yet, that it was the eBay part? Where do you recommend we get the Fan Regulator and Thermal Paste?

 

Moss can you post thes great pics in the Knowlege base for others to use..??

 

That was faster then expected usually they last up to 2 month.
Behr is not a french company but the OEM part for Mercedes,you can find sometimes one on Ebay ,I just bought a new one for $150 otherwise the dealer price is $250 but worth the money.
How I know,I tried twice one of the cheaper ones all from Germany they all didn't last.


I just saw you ordered the KAE,it's made in Berlin Germany it lasted 2 month .
My indy warned me before I bought it but I wanted to save money.

Good luck let us know

Ulf

 

Well, my BEHR unit sounds German but the sticker says Made in France. I just got my KAE version from Autohaus and it has "very efficient" copper based paste instead of the white thermal paste. It is already applied so you just have to mush it down. It also comes with a blue cloth to wipe down (polish) the blower housing heatsink. Hopefully this one will last a while. I found no less than 5 versions available: BEHR, KAE, Bosch, Genuine, and Hamburg Technic. I personally think there are only 2 versions based on the footprint and housing. Typically, one or two major suppliers with different stickers.
AllPartsExpress - quality automotive parts for less!

 

Believe me Behr is the original one ,and like I said I had used the KAE and my Indy ,who is German,told me that they don't use it anymore because of the high failure rate.
Mine KAE lasted 2 month.

Good luck

Ulf

 

zone - heres is your answer

MOS - by measuring the voltages, is that an indication the regulator wasnt functioning right?

 

z168, yeah, that's correct..command a voltage and make an actual measurement at the regulator/fan. My symptom at commanded full speed (12V) only gave me about 3V at the regulator which is equivalent to very slow fan speed.

 

Gentlemen: I'am having the same problem on a 96 140(medium speed is max) Has anyone found a regulator that works long term yet, not from a dealer???
Thanks for any info.

Ron

 

Has anyone found a regulator that works long term yet, not from a dealer???
Thanks for any info.

Ron

Hamburg technic:thumbsup::thumbsup::thumbsup:

Hamburg technic vs Bosch

1 year,daily driver,$ 75.00 on Ebay

3 times stronger then the old Bosch

 

My KAE regulator has been working fine since July1 in the TX heat. $170 from autohaus. I also have a replacement cheapo ebay $75 version on standby......

 

It is possible that a hot environment may actually be less stressful on the regulator as it is likely that your blower will be operating at a higher speed in that situation. When the blower operates at a higher speed, there are two things happening that will extend the regulator life. First there is higher air flow which will serve to keep the regulator temperature down which is good for life. And the voltage drop across the regulator will be less which will reduce the heat dissipated across the regulator.

Conversely, a slower setting of the regulator will make both situations worse. Not a great design but that's the way it is.

 

Someone correct me if this is not right:

Max setting of the blower on the A/C panel is not always "the real maximum". The real maximum speed of the blower will be achieved only if the preset temperature in the cabin is minimal or relatively low (15 °C for instance) and if the real temperature in the cabin is high (40 °C for instance). At least that's how my HELLA regulator works and the original one works also before it died.

In another words, if the cabin temperature is relatively low, then max blower speed is less then if the cabin is hot.

So, is this true?

 

True if your HVAC is in AUTO mode. Go into the diagnostic mode and command 12V or all 7 bars full fan speed and DVM measure to see if your regulator is providing all 12V to the fan motor for verification. If it gets significantly less than 12V, then your regulator is dying.

 

True if your HVAC is in AUTO mode. Go into the diagnostic mode and command 12V or all 7 bars full fan speed and DVM measure to see if your regulator is providing all 12V to the fan motor for verification. If it gets significantly less than 12V, then your regulator is dying.

I went into AC self diagnostic mode and put fan speed to MAX, but I can hear that this is not what it was few months ago when I replaced blower regulator, thus I do not need to measure voltage at the blower at all. I would say it works with 75% of power.

But I also noticed that refrigerant pressure temperature was not under 6 °C during the test. Maybe this influences the fan MAX speed also?

I paid 215 EUR for HELLA regulator, it seems that I will have to buy BEHR at the dealer. is it necessary to use the dielectric paste only at the contact REGULATOR-HOUSING, or at the entire regulator's back side because the new regulator is larger than the original one?

 

A few questions/comments:

1. Did you check that #8 in the a/c diagnostic mode was reading 60 when the fan speed was set at max? If not then the a/c controller may have a problem.

2. I am reasonably certain that the fan speed is not affected by refrigerant temperature if you manually select max. fan speed.

3. Is your external air filter in good condition? - a blocked filter can reduce the fan speed. I would certainly check this before condemning the regulator.

4. The paste is there for its thermal conductivity properties not its dielectric strength. You need a thin film of it to exclude any air (bad conductor of heat) between the area of the regulator's heat sink that is in contact with the blower case. This just makes the blower case act as an even larger heat sink for the regulator's power transistor(s).

Mike

 

A few questions/comments:

1. Did you check that #8 in the a/c diagnostic mode was reading 60 when the fan speed was set at max? If not then the a/c controller may have a problem.

it was reading 60 with fan speed on MAX.

2. I am reasonably certain that the fan speed is not affected by refrigerant temperature if you manually select max. fan speed.

makes sence.

3. Is your external air filter in good condition? - a blocked filter can reduce the fan speed. I would certainly check this before condemning the regulator.

The filter is about 6 months old, 7000 km on road and it was cleaned few weeks ago. It is 99,99% not a filter.

4. The paste is there for its thermal conductivity properties not its dielectric strength. You need a thin film of it to exclude any air (bad conductor of heat) between the area of the regulator's heat sink that is in contact with the blower case. This just makes the blower case act as an even larger heat sink for the regulator's power transistor(s).

The point is that the regulator which I replaced 6 months ago has much larger contact surface then the old one. In another words, the surface on the blower housing which is slightly higher than the surrounding surface is smaller than the surface of the regulator. i assume the new regulator was not mounted properly by me ... but they sold me a regulator as a part which should work with old housing.

Should I modify the housing of the blower to match the surface of the regulator?


This is an update made some time after the above text:
1) if i select internal circulation of the air I can hear full power of blower, thus evidently the air filter prevents full air flow from outside. how is this possible with filter 6 months old?
2) i tried to measure the voltage between the red and blue connector of the blower motor (both plugs disconnected). I expected that according to fan speed selector wheel in the cabin the voltage will be different ... from ca. 1 V to 12 V, but it is constantly ca. 12 V. So I am not able to verify the regulator at all.
Any tip?

 

Should I modify the housing of the blower to match the surface of the regulator?

NO,I just put my new/big one and its OK,NP for the last year.

Old Bosch

New/big H.T.

 

thanks for the two pictures and explanation. I am really bad in electricity ... how can I measure the voltage at the blower motor which should be proportional (inversely proportional) to the blower RPM? Only an exact instructions can help me (please see my edited text above).

 

I don't know the details of the regulator circuit but it maybe that the output transistor doesn't draw any current if the motor is not connected. In this case, the blue line would probably be within about 1 volt of ground potential, giving you about 12 volts between the red and blue lines, whatever you do with the speed control knob.

The red line is connected solidly to the battery +12 volts so that you can check that one when it is disconnected by measuring between it and the car metalwork. For the blue line I suggest that you carefully ease back the translucent insulating cover on the motor connector of the blue line while both red and blue lines are connected to the motor, exposing enough of the blue terminal to get a voltmeter prod on to it. You can then measure between this terminal and ground (car metalwork) at various speed settings. The higher the speed, the lower this voltage should be.

As for your external filter which you now suspect, if it looks OK maybe the air intake itself is blocked with crud.

Mike

 

Thanks for an idea. It is dark now here. I will try it tomorrow. I will also check the air ducts to the blower. Maybe the best solution is to buy a filter without charchoal? I will also check if rotation of the blower is not hindered by worn bearings.

My original post clearly shows were to measure voltage.

Oh yes. sorry, I even did not look at the start of this topic because there is another older thread about this problem ... and there the procedure of measuring is not clear.
I will do it tomorrow, thanks to you, too.

 

So here is the report:

1) I oiled both bearings
2) checked air ducts to the blower ... NP
3) checked brushes on the blower .. still OK
4) measured voltage on the terminals like suggested in this topic: 10,6 V at MAX fan speed, 2,6 V at MIN speed.

It seems that the regulator lost at least 1,0 V. Evidently it started to die.

I paid 215 EUR for it and its HELLA, it is stated BEHR on it. I think the next one will die too. Any tip?

 

I think you are OK with voltage, 1V difference is not bad especially if your car was not on. Mine was so degraded that I only got 3-4V at full speed which was the same as very low speed.

 

Do you have an activated carbon filter? I have an Introduction manual which states that:

'Upon switching on the activated charcoal filter, the blower motor control voltage is increased within 1 minute. This assures a constant air volume from the blower motor.'

I don't have the carbon filter so can't find out the implications of this but it seems to indicate that the voltage across the blower motor would be less if the filter is switched off.

Maybe it's irrelevant to your investigation - I can't tell.

Mike

 

Do you have an activated carbon filter? I have an Introduction manual which states that:

'Upon switching on the activated charcoal filter, the blower motor control voltage is increased within 1 minute. This assures a constant air volume from the blower motor.'

I don't have the carbon filter so can't find out the implications of this but it seems to indicate that the voltage across the blower motor would be less if the filter is switched off.

Maybe it's irrelevant to your investigation - I can't tell.

Mike

I think you are OK with voltage, 1V difference is not bad especially if your car was not on. Mine was so degraded that I only got 3-4V at full speed which was the same as very low speed.

You are genious ... at least in comparison to me. Yes, my car is equipped with a charcoal filter (that one deep under the windshield) and there lies the answer for my paranoid reaction. So, for the engine on, the voltage on terminals is now 11,3 V with filter off, and 12,4 V with filter on. I guess the voltage cannot be more than 12,4 V. If this is true than everything is ok.

So I owe you a beer (Mike pointed on the charcoal filter and Mos onto a difference between the measurement with car on and off). If you can confirm that the voltage on a blower cannot be more than 12.4 V than I will be very happy (I guess ca. 14 V is only for charging the battery, am I right? ... a short explanation of this is appreciated).

many thanks and best regards.

 

If you can confirm that the voltage on a blower cannot be more than 12.4 V than I will be very happy (I guess ca. 14 V is only for charging the battery, am I right? ... a short explanation of this is appreciated).[/ QUOTE]

Hi Samosali,

If you measure the voltage between the red terminal on the blower motor and ground, it should correspond to the battery voltage: around 12.4 V engine off and up to around 14 V engine running, I believe. If you measure between the blue, blower terminal and ground you will get a value that varies with blower speed. It will be a minimum value at maximum blower speed. I am not sure how close this value can go to zero - it depends on the exact details of the blower regulator circuit. Assuming that your alternator is producing 14 V, it would appear that, in your case, the blue terminal voltage goes to a minimum of 1.6 V with the carbon filter on and 2.7 V with it off. I cannot verify whether lower voltages are normal on a 'perfect' regulator.

I think that, if I were you, I would have another beer and forget about blower voltages.

Mike

 

For a typical BJT (bi-polar junction transistor) the minimum voltage drop would be about 1 volt but varies between manufacturers and types.

 

thanks mike and dmac! well maybe i sould paranoic with all this "voltage stuff", but I decided to figure out if something is happening with the regulator. The point is that it is still in warranty, if i will wait, it will be no longer, and then bye bye 200 EUR, which is not reasonable.

dmac, please, a brief explanation of your statement, for a mechanical engineer with almost zero knowledge in electricity would be appreciated. So, is mike's instruction ok? I am interesting mostly in the voltage for a running car between blue terminal on the blower motor and ground. How much should it be to declare that regulator is perfect (or maybe there is some another indicator)? in any case i will perform measurement under mike's instruction and report about it tomorrow. I think this topic is interesting also for others.

If I would guess, I would say that for MAX fan speed I should measure between blue negative terminal on the blower and ground:

a) 1 V (regulator drop) + 1 V (filter off) = 2 V
b) 1 V (regulator drop) + 0 V (filter on) = 1 V

Is that correct?


Thanks again for your time.:bowdown:

 

Samosali,

FYI - by degrees I am also a mechanical engineer although by profession I am more involved in electronics design.

If you're just interested in the regulator function, then I would ignore the effect of the filter being on or off. And if you have verified that you have full battery voltage at the red terminal, then all you really need to measure to check the regulator operation is the voltage at the blue terminal. I do not know the actual specs for the regulator, but I would expect that it would vary from battery voltage to about 1 volt (from minimum speed to maximum speed). When these regulators fail, they are not able to get close to the 1 volt level at full speed.

If you suspect the regulator after testing it, you may find it difficult to get a replacement unit as most manufacturers will not exchange electronic parts once they are installed.

Hope that this helps - Duncan

 

thx again for the reply.
So now and for ever, for everybody who wants to check the regulator this will help a bit (and you told me that I do not dig into the details ):

-for engine OFF the voltage between red terminal on the blower (at the brushes) and ground is 12.4 V .... for engine ON it is 14.0 V.

-voltages between blue terminal on the blower (at the brushes) and ground, for engine OFF and charcoal filter OFF:

a) fan on MIN; 9 V
b) fan on auto; 7 V
c) fan on MAX; 0.7 V

-voltages between blue terminal on the blower (at the brushes) and ground, for engine OFF and charcoal filter ON:

a) fan on MIN; 8 V
b) fan on auto; 4 V
c) fan on MAX; 0.6 V

-voltages between blue terminal on the blower (at the brushes) and ground, for engine ON and charcoal filter OFF:

a) fan on MIN; 11 V
b) fan on auto; 10 V
c) fan on MAX; 2 V (REMARK: a new measurement after several hours in the hot weather showed 1.0 V ... or most probably first measurement was not correct)

-voltages between blue terminal on the blower (at the brushes) and ground, for engine ON and charcoal filter ON:

a) fan on MIN; 10 V
b) fan on auto; 7 V
c) fan on MAX; 0.8 V


I would say that the measurements with engine ON are important for the estimating the condition of the regulator. One can see that indeed the activation of the charcoal filter resulted in ca. 1 V drop, thus if the filter is OFF we do not obtain full voltage (power) on the blower (there is still 1 V reserve for the situation when we engage filter).

The last data then (item c; 0.8V) seems corect then? This is actually so called inherent drop of the voltage due to blower regulator itself ..... ca. 1 V which were you talking about?

 

Somosali,

This is the definitive, wall-to-wall carpeting job for blower voltages. Very good. Time for that beer.

Mike

 

Somosali,

This is the definitive, wall-to-wall carpeting job for blower voltages. Very good. Time for that beer.

:thumbsup:

It seems that there is "pretty complicated" logic in the blower regulator: for engine not running, the blower acually works stronger than for engine running as one can see from the data.

maybe there is some reasonable logic: when engine is not running, the car cannot move also. Thus, there is no additional flow of the air due to vehicle speed and therefore relatively high voltage at the blower to compensate this fact. In contrast, the moving car of course has the enginne running, and the vehicle speed helps to "pump" the air into the cabin, therefore the blower's motor can work on slightly lower RPM by definition. Of course, when the charcoal filter is engaged during the driving, then this effect of vehicle's speed is negligible, therefore, the voltage at the blower is relatively high again.

Note that the above presented voltages indicate inversely proportional relationship to blower output. So, lower voltage means larger output and vice versa.

 

I have to say that I think maybe your interpretation is not quite right.

1. The 'complicated logic' is in the a/c controller: the regulator just does what it's told - or not, as the case may be!

2. The blower motor is being energised by the difference between the red and blue terminal voltages and these are a bit larger with the engine running.

Mike