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  #1  
Old 08-19-2001, 08:54 PM
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Location: New Bedford, MA USA
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Another Weird developement.

Well, the tranny is fixed and she is smooth as molasses on a warm day. Today was a warm day, and although the tranny was on target, the blower fan quietly self-adjusted itself to zero. Had switch set to max temp to min. enjoying the cool, dry air when suddenly the blower speed went from max to nothing in about 5 minutes. No setting or switch affected the operation of the blower. Checked all fuses, etc. Pulled the ACC unit, opened it up, all looked good, but again, I do not have a schematic for the pinouts on this unit. Think 9 and 11 on left are for monovalve, but otherwise. .Question...Anyone had this happen? Question, blower fuse is showing 12v, but no blower. is feed after ACC or before. My diagram is not too clear. I'm betting the ACC has gone south Any opinion or advice as always is much appreciated..
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Jeff Lawrence
1989 300e
2000 Dodge Grand Caravan SE
No matter what you fix, there will always be something else to fix..
"Warranty" is just another way of postponing the inevitable.
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  #2  
Old 08-19-2001, 09:04 PM
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Be sure that you don't have a separate blower fuse outside and forward of the regular box. Sort of like a glow fuse. If all this is fine, there is a three wire connector on the firewall next to the brake booster. I think its a yellow wire (but check on your diagram) that is the blower control signal from the pushbutton controller. This signal should vary from 1v to 6v as the blower speed is increased. The blower is under the hood and the regulator is under it. The regulators on the 124 body have huge heat sinks and go bad infrequently. It is a big power transistor that amplifies the output in proportion to the input signal - It is on the ground leg of the circuit)

The blower is more often the problem. The signal from the PBC is not often the problem.
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Continental Imports
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33 years MB technician
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  #3  
Old 08-20-2001, 12:46 PM
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Well, here's what I've got. Blower motor is OK (bench tested). ACC control appears to be sending correct signal to the blower regulator, ie. about 1.25v on low speed and about 7.66v on high speed. These are measured at the connector (yellow wire) on the firewall and at the terminal on the regulator module. The output to the blower (red wire) shows about 12.4 volts. Blue (which is the ground for the blower) wire is floating, ie. not grounded. If the blower speed is regulated by the module (which is dissapating a lot of heat) and the control is in the ground leg which is open, then I guess it's the module which is kaput!! What is this called in Fast Lane. Perhaps regulator switch? Steve, does this sound about right to you??
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Jeff Lawrence
1989 300e
2000 Dodge Grand Caravan SE
No matter what you fix, there will always be something else to fix..
"Warranty" is just another way of postponing the inevitable.
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  #4  
Old 08-20-2001, 01:00 PM
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Join Date: Aug 2001
Location: Florida
Posts: 272
I had an 87 E that did the same thing. When I took apart the blower motor I found a twig that had gotten through the intake screen and worked its way between the magnet and armature. Since it did this gradually it took a couple of days to stop completely but stop it did. May not be your problem but maybe the motor has lost it's ground. Good luck
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  #5  
Old 08-20-2001, 02:57 PM
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Should be called a "Blower regulator" part # 124 820 27 10.
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Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician
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  #6  
Old 08-20-2001, 07:47 PM
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Location: New Bedford, MA USA
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All fixed.. Was the regulator. Picked one up locally at the Benz boneyard for $10. Thanks for the help and suggestions. BTW, if anyone out there has occasion to remove the blower motor, take a good look at the A/C evaporator core. Mine was covered with 26 different brands of crud. Cleaned it up and gained another 10 degrees of cool at the center ducts. No kidding, it was really full of crud. Thanks again Steve..
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Jeff Lawrence
1989 300e
2000 Dodge Grand Caravan SE
No matter what you fix, there will always be something else to fix..
"Warranty" is just another way of postponing the inevitable.
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  #7  
Old 08-20-2001, 08:20 PM
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How did you clean it?
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Jim
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  #8  
Old 08-21-2001, 09:26 AM
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Jim, I did it in two steps. First, I sprayed the front face of the evaporator with some CRC Brake Kleen which did a nice job of dissolving all of the oily black crud imbedded in the cooling fins. I really flushed it good with this stuff (used 2 1/2 cans). After that evaporated, I sprayed the core with Coastal Power Cleaner, let it soak for about 20 minutes, flushed it with the hose and repeated the Coastal treatment again. Really gave it a good flush with the hose. All of the crud and water drained thru the evaporator drains. You should have seen the mess of stuff under the car. Side benefit, got rid of that funny mouldy smell that I noticed for the first couple of minutes of A/C operation.
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Jeff Lawrence
1989 300e
2000 Dodge Grand Caravan SE
No matter what you fix, there will always be something else to fix..
"Warranty" is just another way of postponing the inevitable.
Reply With Quote
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