I have done this job many times over the years and never had this
problem.  I have used the German motors many times and even a Chinese
one not too long ago.  I have never heard of Thermex before.  Where did
you get it?  The Chinese ones are blue box.  I would try to feel what is
vibrating.  It could be that the motor fan itself isn't balanced
properly and this is causing the problem.  They normally check this at
the factory and I always check my fan motors after I have installed them
in the heater box but before I put the dash back on.  That way if there
was a problem, I could address it before everything was all the way back
together.

Let me know if I can help you,
Ken Wilford
John 3:16
www.vanagain.com

Kevin Gilbert wrote:
> Volks,
>
> My newly-installed heater blower motor vibrates the dash like the bed
> in a cheap motel I'd like to forget.
>
> I've replaced the original in my '84 Westy with a new Thermex unit. I
> attached spade terminals to connect to the newer-style plug on the
> motor. I replaced the narrow foam weatherstripping that seats the
> motor. The heater box is in good condition, and all the screws and
> clips that came out, went back in.
>
> Also, the sliders for the heat controls now almost touch, preventing
> the knobs from attaching without interfering with the adjacent slider.
>
> It is entirely possible this a 'fix one thing, break two or three
> others' kind of project. :)
>
> Any suggestions?
>
> Thanks.
>
> Kevin
>