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  #1  
Old 01-23-2018, 06:21 PM
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a/c blower work with key on, can not be turned off

Just changed the motor of the blower,

is turning when key on, does NOT turn off threw the climate control,

Disconected the climate control two plugs,

Still on,

What did I wrong again?

Did I wired it wrong ,+to - ?

thanks in advance,

300SDL, california,

Brushes where bed ,

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  #2  
Old 01-23-2018, 08:34 PM
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Fan speed control is probably toast (shorted transistor). It's the module with the heatsink on it up in the blower housing.
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  #3  
Old 01-23-2018, 08:44 PM
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Blower shorted resistor,

Thanks for replying,

any idea of replacing the power transistor ?

could not find information,

Thanks again,
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  #4  
Old 01-23-2018, 08:53 PM
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You have to replace the entire module, it's encapsulated in epoxy. If the fan motor were in poor condition, the brushes arcing badly enough can cause the transistor to fail in a shorted condition. When it does, it doesn't matter what button you push on the CCU, the fan will always run max speed.
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'94 BMW 530i Touring - "BMWtf LoLwagen" 233k
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  #5  
Old 01-23-2018, 09:13 PM
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Thank you Diesel300

Thank you Diesel300
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  #6  
Old 01-24-2018, 01:36 PM
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Diesel300 is smarter than me. OP just stated "300SDL". Does that tell a year range? Also "Brushes where bed" might mean something.

My 84-85 300D have just mechanical relays in the "blower control box". Even my 1996 Voyager has mechanical switches and resistors. My 2002 T&C blower is transistor controlled, but only because the optional digital ATC. It similarly runs "always high-speed" when the transistor "resistor"-pack fails, though it can be turned off.
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  #7  
Old 01-24-2018, 07:49 PM
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300SDL means it's a 1986-1987 model. Unlike the earlier models with relays and an actual blower "resistor", the 1986+ cars are solid state with a transistor pack in the blower plenum. On the SDL's the key switch has a dedicated contact to the blower motor, if the transistor pack fails shorted, the blower will run when the key is on, but not when the key is off, and always at the same speed regardless of input from the CCU.
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'11 Honda Accord EX - "The Daily" 69K
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  #8  
Old 01-25-2018, 12:27 AM
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made a gamble with the solid state "resistor" from 300SL

Did order Heater Blower Motor Regulator Resistor 1298213351 For Mercede 300SL 500SL SL320
( 202141416589 )

From Ebay, $20,

Looks similar to my control,

Will give it a try,
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  #9  
Old 09-15-2018, 08:29 AM
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Question...

I have an ‘87 SDL that the blower will come on in the off position. It will also quit in the on position. If the fan is set to low speed then the blower will come on on it’s on going down the road at low speed. If it’s set on high speed then it can also come on on it’s on at high speed even with the switch clearly in the off position. If I press the off button and hold it then the blower will stay off until I release the switch. Sometimes it will stay off until I press a selection on the climate control unit. Every time it comes on on it’s on the AC compressor comes on too. In other words, mine comes on with the key switch 95% of the time and blows according to the selected fan speed. It will shut off on it’s on. Every time it’s on the AC compressor is on. I hate electronics! ��
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  #10  
Old 09-15-2018, 10:55 AM
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Exclamation EIGHT Months later....

Did the spare part fix it ? .

-Nate
Quote:
Originally Posted by rreeuuvveenn View Post
Did order Heater Blower Motor Regulator Resistor 1298213351 For Mercede 300SL 500SL SL320
( 202141416589 )

From Ebay, $20,

Looks similar to my control,

Will give it a try,
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  #11  
Old 09-15-2018, 11:16 AM
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Quote:
Originally Posted by oilslick View Post
I have an Ď87 SDL that the blower will come on in the off position. It will also quit in the on position. If the fan is set to low speed then the blower will come on on itís on going down the road at low speed. If itís set on high speed then it can also come on on itís on at high speed even with the switch clearly in the off position. If I press the off button and hold it then the blower will stay off until I release the switch. Sometimes it will stay off until I press a selection on the climate control unit. Every time it comes on on itís on the AC compressor comes on too. In other words, mine comes on with the key switch 95% of the time and blows according to the selected fan speed. It will shut off on itís on. Every time itís on the AC compressor is on. I hate electronics! ��
The pushbutton units are well known for bad solder joints, especially on the push button switches themselves. Poor connections or broken solder joints will cause the behavior you're describing, the biggest indication being that it will stay off if you hold the "off" switch.
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'11 Honda Accord EX - "The Daily" 69K
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'91 350SD - "Diseasel Jr." 173K
'94 BMW 530i Touring - "BMWtf LoLwagen" 233k
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  #12  
Old 09-15-2018, 11:28 AM
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Question Klima II P.B.U.'s

? Who re solders them ? .

I bought a rebuilt one from that place in Florida, they don't .

TIA,
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  #13  
Old 09-15-2018, 11:42 AM
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The 1986+ cars are very different from the earlier cars. The PBU is full of electronics. Opening the unit and unclipping the PCB's will get it to where you can work on it yourself. Resoldering is a DIY job if you know how to solder.
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'11 Honda Accord EX - "The Daily" 69K
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'91 350SD - "Diseasel Jr." 173K
'94 BMW 530i Touring - "BMWtf LoLwagen" 233k
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  #14  
Old 09-15-2018, 08:15 PM
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Fixed!

I replaced the control panel with one of my spares and all is well. Thanks!

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