'86 300SDL Under-Dash Panel Removal

'86 300SDL Under-Dash Panel Removal - Passenger Side

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eddie - 05 Feb 2005 14:29 GMT

I am trying to repair my heater blower motor and have gotten stuck in
removing the under-dash panel passenger side. I removed the three
screws at the top of the upholstery panel and there is also a plastic
rivet.

The panel did not come away freely after removing these screws and is
apparently secured in other locations.

I cannot identify where the other points of attachment are located and
need detailed instructions.

Does the upholstery panel and the plastic panel below it come of as one
piece, etc.

Thanks

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Richard Sexton - 07 Feb 2005 00:07 GMT

>I am trying to repair my heater blower motor and have gotten stuck in
>removing the under-dash panel passenger side. I removed the three
[quoted text clipped - 9 lines]
>Does the upholstery panel and the plastic panel below it come of as one
>piece, etc.

Yes they can but they do come apart.

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marlinspike - 08 Feb 2005 00:12 GMT

I take it you are following the instructions in the service manual? I did,
and it had me stumped for a long time. The service manual writers screw up
from time to time, and this is one of those times. there is absolutely no
need to take off that upholstry piece. Just put the seat all the way back,
stick your head in the footwell (look up) and your legs on the seat and take
off that black plastic panel. You will then see the screws that hold the
blower motor on and it will be easy to replace it.
Richard

> I am trying to repair my heater blower motor and have gotten stuck in
> removing the under-dash panel passenger side. I removed the three
[quoted text clipped - 11 lines]
>
> Thanks

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eddie - 08 Feb 2005 19:39 GMT

Thanks all for the help. Problem fixed. Service manual instructions
were "incomplete".

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Richard Sexton - 08 Feb 2005 20:04 GMT

>I take it you are following the instructions in the service manual? I did,
>and it had me stumped for a long time. The service manual writers screw up
[quoted text clipped - 4 lines]
>blower motor on and it will be easy to replace it.
>Richard

Yeah true, but it's nice to clean the upholsetry while it's off. It
can get pretty dusty under there.

There's a balck plastic shield or cover that is between you and the
blower motor. It is held in place by 3 or 4 philips screws AND
has some plastic tabs that lock it into place at the rear of
the upholstery piece. That might be what's messing you up it got
me the first time.

If you're still stuck I can send pics as mine is aaprt right now for
cleaning anyway.

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eddie - 08 Feb 2005 21:52 GMT

Thanks for all the help. I was finally able to pull the heater blower
motor with the intent of replacing the brushes. Before repairing the
motor, however, I applied 12Vdc directly and the motor works fine.

The motor therefore was not the problem with the blower fan not
working. Next to the motor is a finned aluminum "heat exchanger" with
three input wires out to a plug and a red and blue wire going to the
motor.

I suspect that there is an over temperature sensor on the "heat
exchanger" that may have failed in the open position because I do not
get continuity across this unit from the blue motor wire to any pin on
the plug.

I do get continuity from a pin on the plug to the red motor lead.

3-Wire Plug -> Finned Aluminun Heat Exchanger -> (Red & Blue Wire) ->
Motor

Can anyone confirm that there is a normally closed (NC) overtemperature
contact on the Finned Aluminun Heat Exchanger?

(Since I have voltage on the female end of the plug I do not believe
that the pushbuttons are an issue. Any other trouble shooting tips will
be appreciated.)

Anyone with a circuit schematic?

Thanks

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Richard Sexton - 09 Feb 2005 14:31 GMT

>Thanks for all the help. I was finally able to pull the heater blower
>motor with the intent of replacing the brushes. Before repairing the
>motor, however, I applied 12Vdc directly and the motor works fine.

Ok, BTDT. There's all sorts of bits and pieces to maknig thr
automatic climate control work. But, the one that fails 99%
of the time IMO is the climate control pushbutton assembly.

It's where all the logic is to drive the whole system. There's
5 or 6 relays on there packed between two curcuit boards that
get too hot; traces sometimes vaporize off the board.

You need to get a new one of these although new is perhaps the
wrong word as they're bicg bucks new. You can usually get one
off ebay for about $50.

When/why did it stop working? Blowing any fuses? Upgrade the stereo?

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