PeachParts Mercedes-Benz Forum - Blower Regulator install

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Blower Regulator install

Hi,
Can anyone tell me the simplest way, or only way to install a blower regulator on my 94 E320. Thanks.
Bob

If you search for the blower motor removal instructions, use those and underneath the blower is the regulator. I was able to find them, and use them this morning for a blower removal on a 1988 300E. The only problem is the pictures are thumbnails only, as the links to not work anymore, but you can get an idea from the thumbs how to do it. try searching for w124 blower removal and that should bring up the thread. the good link is on page 2.

... and do yourself a favor while in there and change the 2 filters..

Blower Regulator

Thanks so much, guys.

How did you determine you need a regulator??

Blower regulator

I had changed the blower a while back as it was defective. Thinking the replacement was bad after having the same basic problem, I tested the new and it tested fine. Also, there was a 12v reading at the blower. The climate control switch also tested fine. Thanks for asking. Bob

Cool..
Just did not want to see you tear all that out only to find that there was no 2-8 v. trigger sig to the regulator from the CCP..
common mistake..
Good Luck.

Blower regulator

Thanks again for the interest in my problem. However, now you've got me thinking. Could it be the trigger signal after what I've done? If so can you please tell me how to check it? Thanks again. Bob

OK..

Reading your first post, I had not realised you already had been down to the blower/reg department..

..anyway, the reg needs a low voltage signal from the CCP in order to trigger the switching transistor in the regulator.. once that is done , the regulator completes the ground of the blower circuit via blu wire [ this is a switched ground circuit,.. in other words, rather than a normal switching of a Hot side .. the switching is done on the neg ground side of the circuit]
So , when you say you have power to the blower , if you just mean you have power to the red side of the blower , that is not good enough..the red side is always HOT.. you would have to have power to both sides of the blower for it to be a complete circuit.
That is where the reg comes in.

There is a couple of simpe test points to check if you have a meter or test lamp

Behind the brake booster , on the firewall, there is a 3 wire connector .[red.blk/yl] you should have 12v across red and blk, but you should also have 2-8 volts from yellow to blk [ or gnd], depending on the speed setting at the CCP.. this is the signal that goes on down to the reg and triggers it to let the blower circuit complete to ground. The reg does the heavy work, while the trigger does not have to carry that blower load. And by varying this low volts
trigger, the reg mirrors these inputs to regulate the speed of the blower.
If this test proves you have trigger V , then the reg is prob at fault, but there is one more simple test.
But ya got to get down in there for this test:
Two wires at blower , red and blu.. if you attach a jumper wire at the blu at the blower and ground it, does the blower run on high?? ...if yes , replace reg.
You can now see that grounding the blu side of the blower simply eliminates the regulator and its function , which is to ground the blu wire when the trigger sig tells it to..thus completing the blower circuit.
End of story

Blower regulator

Please accept my sincerest thanks and appreciation for you to have taken the time to explain that to me. You are such an asset to this site. Thanks again. Bob

I was wondering about that myself too, thanks. I can't quite do that test yet though, the blower motor has a good half inch of play up and down on the shaft...

94 E320 regulator

Johnhef and Arthur Dalton thanks so much for your help. I've istalled the regulator and the blower now works fine. Bob

I am trying to replace the regulator myself but can't quite figure out to get the heat sink out. Is there a special trick to it?

if there is no power in the yellow to blk wire , what then

Quote:

Originally Posted by Arthur Dalton (Post 932315)

OK..

Reading your first post, I had not realised you already had been down to the blower/reg department..

..anyway, the reg needs a low voltage signal from the CCP in order to trigger the switching transistor in the regulator.. once that is done , the regulator completes the ground of the blower circuit via blu wire [ this is a switched ground circuit,.. in other words, rather than a normal switching of a Hot side .. the switching is done on the neg ground side of the circuit]
So , when you say you have power to the blower , if you just mean you have power to the red side of the blower , that is not good enough..the red side is always HOT.. you would have to have power to both sides of the blower for it to be a complete circuit.

if there is no power at the yellow and black wires , what then.?
That is where the reg comes in.

There is a couple of simpe test points to check if you have a meter or test lamp

Behind the brake booster , on the firewall, there is a 3 wire connector .[red.blk/yl] you should have 12v across red and blk, but you should also have 2-8 volts from yellow to blk [ or gnd], depending on the speed setting at the CCP.. this is the signal that goes on down to the reg and triggers it to let the blower circuit complete to ground. The reg does the heavy work, while the trigger does not have to carry that blower load. And by varying this low volts
trigger, the reg mirrors these inputs to regulate the speed of the blower.
If this test proves you have trigger V , then the reg is prob at fault, but there is one more simple test.
But ya got to get down in there for this test:
Two wires at blower , red and blu.. if you attach a jumper wire at the blu at the blower and ground it, does the blower run on high?? ...if yes , replace reg.
You can now see that grounding the blu side of the blower simply eliminates the regulator and its function , which is to ground the blu wire when the trigger sig tells it to..thus completing the blower circuit.
End of story

if you find no power at the yellow and black wires what could be wrong ,

Control panel. I had that problem on my 91 300D that turned out to be a cracked solder joint at one of the connectors (don't remember which). Check all the solder joints on the printed circuit board at both plugs using a strong light and magnifier. If you see a small circle around the pin you have found the problem. Re solder.
Paul