1992 Mercedes - Climate Control Problem

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Geschichtlich - 30 Jul 2007 14:57 GMT

I certainly hope that somebody out there can help me out with this
one.

The car in question is a 1992 Mercedes 300D 2.5 Turbo. The A/C blower
motor failed about a month ago, and I had the motor and regulator
replaced. The AC system itself is tight, recently replenished with
coolant and generates ample cold. The problem is that the amount of
air pumped into the cabin, even when one sets the controls on high, is
very low. The motor sounds very loud, but the resulting air flow is
very weak. Moreover, there doesn't appear to be any obstruction in
the system. The only theory that seems remotely plausible is that
despite generating a great roar, the new blower motor is somehow very
weak.

Ideas? Solutions? I sure could use some experienced advice.

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John S. - 30 Jul 2007 16:49 GMT

> I certainly hope that somebody out there can help me out with this
> one.
[quoted text clipped - 11 lines]
>
> Ideas? Solutions? I sure could use some experienced advice.

A family member has a 1994 420 and I'm amazed at how weak the fan and
AC system is. It has been that way since new.
The fan control on that car is a 2 position switch: 1. Very slow.
2. A little faster than slow.

The roaring sound in your car may be caused by air backing up behind a
vacuum operated air door that is not opening. A hose may have been
knocked off during reasssembly. I would take it back to the dealer
that did the service.

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Scott Dorsey - 31 Jul 2007 15:14 GMT

>The car in question is a 1992 Mercedes 300D 2.5 Turbo. The A/C blower
>motor failed about a month ago, and I had the motor and regulator
[quoted text clipped - 8 lines]
>
>Ideas? Solutions? I sure could use some experienced advice.

Is it louder than the old motor was?
Did they replace the motor and the squirrel cage as well, or just the
motor?

If the blower is not screwed onto the motor shaft properly, it will make
noise but not move air. If there are leaves and debris in there or the
motor is not aligned in place right, the blower can be scraping against
something and making lots of noise without moving muh air. Take it back
to the tech that did the work.
--scott

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"C'est un Nagra. C'est suisse, et tres, tres precis."

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Geschichtlich - 01 Aug 2007 15:12 GMT

Fellows,

Thanks for taking a moment to address my problem. The problem is
pretty vexing, especially for the guy who did the work in the first
place. He went back in late last week and adjusted the squirrel cage,
which clicked when the motor started and shut off, and re-checked the
seal around the housing in which it's situated. His operating
assumption right now is that the motor itself is bad - too weak,
perhaps, and he intends to send it back and replace it with another.
But I'll pass along the possibilities you've cited here. Should any
others occur to you, I'd really appreciate it. The car only has 90k
on it and is in lovely condition otherwise. I'd hate to have to sell
it because of this, but what other choice would I have? The
temperature here is murderously-high in the summer, and driving
without AC is simply not an option.

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