W115 Blower motor replacement - Mercedes-Benz Forum

 
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post #1 of 9 (permalink) Old 04-24-2015, 09:31 AM Thread Starter
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W115 Blower motor replacement

Anyone happen to have a link to instructions on the best method to access the blower motor? I have a non functioning one in the car (1970 250 no A/C) I need to test/replace. Even a wiring diagram would be helpful as I would like to test the motor directly. Thanks in advance.

Last edited by mikewerks; 04-24-2015 at 09:50 AM.
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post #2 of 9 (permalink) Old 04-24-2015, 10:18 AM
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Heat or A/C blower?

They are separate. The usual malfunction is the crossover switch (micro switch on the side of the console, up by the accelerator pedal) does not engage.

Check there first.
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post #3 of 9 (permalink) Old 04-24-2015, 10:22 AM Thread Starter
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Thanks Mike my 115 has no A/C and my symptoms are turn on heater fan blow fuse so I'm fairly confident the fan is seized but like to confirm before major surgery...
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post #4 of 9 (permalink) Old 04-24-2015, 11:16 AM
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Well there's good and bad news.

Many times the motor is seized up due to either lack of lubrication (can't be prevented as there no way to easily access the bushing) or by a cluster of leaves, pine needles, etc. which has found it's way into the intake.

External partial access can be gained by removing the wipers and upper ventilation grill. There is a sheet metal air deflector which almost completely blocks access to the motor. Many people have reported success by clearing out the debris using a thin wire such as a coat hanger and a shop vac. They have also managed to spray lubricant onto the bushing area using a long thin tube. PITA but it's worth a try. Sure beats pulling the heater box which is the other option.

Pulling the box isn't hard. Just takes time and patience. It's easiest to pull the front seats out for ease of access. Seats, center console and upper console all need to be removed to gain access to the blower box itself. The heater hoses have to be removed to remove the heat exchange unit. Once you remove the box you will see the fan and its mounting bolts. Three of them if I remember correctly.

Now's the time to have the heater core re-furb'ed since it's out already. I usually rebuild the box installing new gasket material since it's already apart.

The good news? You don't have the A/C shyte in your way.

First time to do it? Figure on about 6 to 7 hours total. The second time? You usually find someone else to do it.
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post #5 of 9 (permalink) Old 04-24-2015, 11:23 AM Thread Starter
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I did look at removing the chrome access grill but it appears to have been pop riveted on to the cowl... Is this factory or am I not looking in the rite place for removal. And yes Im happy not to have all that A/C garbage to deal with..
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post #6 of 9 (permalink) Old 04-24-2015, 12:39 PM
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If it is as original, those "pop rivets" are actually fasteners. The "centers" are just push through pins. Use a small punch to push them the rest of the way through and the larger bits come out using a thin, flat blade. The fun part is finding the little centers after they fall into the recesses.

If you replace them with pop-rivets, be sure to use aluminum pop rivets and not steel. The grill is made of polished aluminum. Steel rivets will quickly rust and stain the aluminum. The steel will also erode through the softer aluminum.
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post #7 of 9 (permalink) Old 04-24-2015, 12:51 PM Thread Starter
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Perfect info Mike! I will give it a go and with any luck will be able to locate those centres...
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post #8 of 9 (permalink) Old 04-26-2015, 03:47 PM Thread Starter
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Tip worked great fan was hard to turn. Lubricated and let soak over night. Sad news is still no fan working despite now turning freely. I did "hot wire" the fan to confirm. Now on to the heater box.
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post #9 of 9 (permalink) Old 05-01-2015, 12:38 AM
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A drinking straw with a bit of ATF. Cap the bottom with your finger and place the tip at the bushing side of the fan, then dribble the ATF. Spin the blades a goodly amount so that it works its way through. The fan hook up is on the firewall. You can unplug the pigtail and use small gauge wire hooked to the battery with alligator clip at the ends. There are four posts. Pick one to be hot and try the other three with the negative lead. Fan is three speed, so when you find one that works, you know you have at least one side hot. See if you can get the fan to move in all three speeds.

The fan is not useful for heating. It is only a defog fan. Most of the heat for the cabin is from having fresh air flow over the heat exchanger at speed. One of the levers closes a flap so the cold air does not come into the cabin while the hot air is routed to the dash vents.

Shop time to replace the fan (which is hung at the factory and the car built around it) is 12-15 hours. The fan is sort of NLA, but retails in the $700 range. Shop rates are $95-180/hr. A few people choose not to remove the interior of the car, dash and all, but go through the fresh air vent, cut out the metal shield and pull the fan from the outside. Much quicker, but no less complex.

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