In a previous article "Steve@carolinabreezehvac" writes:
:
;
:"Blue" wrote in message ...
; It is counterintuitive but "pulling a vaccuum" is easier on the fan than
: moving air. To see that in action try holding your palm against the
;intake
: of a hair dryer. The motor speeds up.
;
:And do that to a CAH and you get a motor that does not last long..

A forced air HVAC blower motor is an induction motor, and spins at
about the same speed at all load conditions below the point of
stalling. Blower motors sit outside of the conditioned air stream:

http://ask.bairdwarner.com/content/R...?ASK=3.414.240

They are passively cooled. They should therefore be just as happy
"pulling a vacuum" as they do otherwise.