Date: Sun, 15 Jan 2012 17:04:37 -0500
Reply-To: David Beierl <dbeierl@ATTGLOBAL.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: David Beierl <dbeierl@ATTGLOBAL.NET>
Subject: Re: Heater blower motor questions
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At 03:25 PM 1/15/2012, Jim Felder wrote:
>Is there a way to get—or any point in getting—behind the blower end of the
>frame and armature?
All blower motors that I've freed up have lasted
years without further problems.
Procedure as follows: see
https://picasaweb.google.com/dbeierl/VanagonAnatomyOfABOSCHHeaterBlowerMotor?authuser=0&feat=directlink
for photos of the motor.
Note - it's been a while since I've done this, so I may be off in some detail.
1) Split blower housing by releasing tabs.
2) remove wire clips holding motor into plastic
sleeve. Mark the motor orientation in the
housing. Place housing on the open jaws of a
vise or other support so that the jaws support
the motor sleeve but don't cover the edge of the
motor. Remember you will need room for the motor to fall from the sleeve.
3) Press the blower wheel down and verify that
the motor moves reasonably easily in the
sleeve. Get the edges of the motor past the vise
jaws and adjust vise for maximum support.
4) Note how far the blower is inserted onto the
shaft. Using a drift and large hammer, tap the
motor shaft out of the blower wheel. Make *sure*
that the edge of the motor isn't catching. As
you near the end the shaft will drive
easier. Get a hand underneath to catch the motor
as it falls out, as it will be damaged if it
drops end-first onto a hard surface. Set the
wheel aside, being careful not to dislodge any
metal balancing clips on the blades.
5) Examine motor. All the ones I fixed had
brushes worn 1/4 or less and were seized
up. Commutators looked good. A motor that
screams horribly (bearing chatter) when started
needs new bearings and cannot be repaired in practical terms.
6) Drop Marvel Mystery Oil or similar outside
each end and work the shaft in and out and rotate
it. Wipe off crud as it emerges and re-oil. Run
the motor for a few seconds. Wiggle, wipe, oil,
run etc. for several cycles until no further crud
emerges. When motor turns sweetly...
7) Soak up MMO as much as possible. Lube inside
and outside of shaft with light machine oil
(Supco MO98 turbine oil is good), and fill the
felt ring inside each bearing with oil (see photos).
8) Clean and dry commutator. Brake cleaner on a
rag is good. If necessary (probably not) sand
lightly with very fine sandpaper (800 grit is
probably pretty good). Do not use emery. Gently
scrape any junk from between the commutator
segments with a soft tool that will not scratch
or deform the copper. Clean and dry again if needed.
9) Run motor on the bench for a couple days,
checking periodically. If more crud comes out
wipe it from inside and outside and add clean
oil. There should not be much sparking at the
commutator - trails of sparks indicate conductive
material still between the commutator segments.
10) Observing orientation, press motor back into the housing.
11) Rest the motor shaft on a hard heavy surface
and use a hammer and block of wood to tap the
blower wheel back onto the shaft. Set the depth
the same way as before it was removed.
12) Replace the wire clips holding the motor in.
13) Before closing up the housing, run the motor
and make sure all is well and wheel is balanced. Close up the housing.
14 - Load test motor. The Bosch blowers I've
tested draw about twelve amps from a fully
charged battery (engine not running/charger not charging).
[15) - glue protective cap over the end of the
motor. If you cover the entire end, leave a hole for ventilation.]
>Now it runs like a top, but I would like to know more about the condition,
>like how much current should it be drawing. How do I accomplish that? I
>have voltmeters but need to improve my ability to use them.
You need a meter that will measure more than 10
amps DC. Place it in series with one lead to
the motor. If you don't have access to such a
meter you can build a shunt out of copper wire
and use your 200 mV digital voltmeter to measure
across it. More later if you need it.
>Finally, is the front blower motor different from the rear.
Yep. Rear is smaller.
Yours,
David