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#1
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Heating / AC blower motor
Here is the thing. I got to the blower motor tested the wires. I get 12.3 volts when I put the Control on Defrost. I get nothing anywhere else. AND when the voltage goes to the motor it does not turn on something just clicks. I am thinking that my brushes are bad and also the controller. Can anyone verify this? Thanks This is one of the best forums i have been on.
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#2
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It says 79 300SD in your nametag, so I'll guess it is this model.
If this is the AC servo unit in use up until 1980 under the hood, (Big black plasticy looking thing on right fender above the alternator), then it has a vaccum operated switch that only allows blowing air on defrost. To bypass the switch and get the blower to work with all the buttons whenever you want do this: Two vacuum lines come out of the bottom of the servo, probably yellow and black, and short. Find where these two line go into the longer vacuum harness above. You need to put in a piece of vacuum line that connects the harness Y shaped rubber for the balck to the Y shaped rubber for the yellow. This wil leave the two short lines to the servo disconnected and open, and basically jumper the black to yellow. You'll need a couple vaccum connectors and a short (under 1 foot) piece of rubber tubing to do this (any autoparts store). This overrides the systems cold engine lock out of the blower. Now the fan will blow when Lo or Hi are used. I just discovered this trick last week and it worked for me. One more thing: You probably need the brushes replaced on the blower. Take you no more than 1 hour to remove the blower and visually inspect the brushes. I seem to remember that bad brushes also cause blower to only run on Defrost. But your voltage readings indicate the culprit is the cold engine lock out of blower.
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80 300D 340K Owned 30 yrs 83 300SD 440K Owned 9 yrs - Daily Driver 150mi/day 02 Z71 Suburban 117,000 15 Toyota Prius 2600 miles 00 Harley Sportster 24k 09 Yamaha R6 03 Ninja 250 |
#3
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rhodes2010
I do have an 80 i registered this nambe before i bought the car and the girl said it was a 79 i can not figure out how to change the name with out re registering. When i tested the blower motor the engine was cold. Does this make any difference ? The car is apart and i can see the blower motor bolts so taking it out will be real quick. Thanks |
#4
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I have just extracted my blower motor and then spun it a few times and now it works, But still does not work on anything other than defrost.
Any clues? |
#5
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Quote:
John '80 500SE AMG (yes, it's a real one) '80 300SD |
#6
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The motor is still out of it's housing. and i have to hold it while it is on. It seems at different angles the speed changes.
I have also heard that you can get replacement brushes. Where might i get these and how do i get the motor open to replace them? |
#7
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Okay. Here we go.
Two things (and plenty folks here know more than I do, but I just pulled two of these out last weekend and am waiting for my brushes). 1. That vacuum bypass I describe above in post #2 allows the blower to run when the engine is cold. When the engine is cold the blower is specifically designed to NOT run in any speed but Defrost. The complete technical description of the Cold Engine Lockout Switch is here: http://www.imperialclub.com/Repair/Lit/Master/281/page09.htm The complete book is here: http://www.imperialclub.com/Repair/Lit/Master/281/cover.htm Good reading. 2. Remove the fan and motor from the black plastic housing to get at the brushes. The brushes are visible inside brass square holders at the fan motor opening at the opposite of the fan end. I ordered brush number 54H from carbonbrush.com here: http://www.carbonbrush.com/automotivebrush.htm But... I have not received them nor installed them yet. But I will tell you they are dimensionally correct. .312" x .312". Others will guide you to the **************.com kit here: http://www.**************.com/store/item.php?item=123/116%20Heater%20Motor%20Repair%20Kit%20w/%20Brushes Still others can tell you that any electric motor repair shop and even Ace hardware also have brushes. Plenty of reasons and resources - to do this.
__________________
80 300D 340K Owned 30 yrs 83 300SD 440K Owned 9 yrs - Daily Driver 150mi/day 02 Z71 Suburban 117,000 15 Toyota Prius 2600 miles 00 Harley Sportster 24k 09 Yamaha R6 03 Ninja 250 |
#8
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Confused
I'm a bit confused here. The end of my fan motor opposite the blades is welded shut so I don't see how I could replace anything in there. Considering the original poster is suffering the exact same symptoms as me the cure might also be the same. AmI just missing something obvious in you post?
John '80 500SE AMG (yes, it's a real one) '80 300SD |
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