In a previous article "Steve@carolinabreezehvac" writes:
:
;Afraid not..and it can be proven with a remote tach.

http://www.engin.umich.edu/labs/csdl.../ac/induction/

As you can see, the speed of an induction motor does not vary much
around its full-load speed over its useful load range. If you increase
load on it, it slows down a bit and then stalls. If you take away all
load, it doesn't go faster than the syncronous speed, which is only
slightly faster than the full-load speed.

If you didn't understand what I meant before, I said this fact
contradicts your claim by implication that the motor will not last long
because it will spin itself into destruction when the input is
blocked:

"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.

Your reply:
And do that to a CAH and you get a motor that does not last long..

As any speed up from reducing the load will be quite minimal.

Certainly if the motor is completely enclosed and there is no air
circulation, the motor can overheat no mater what load was placed
on it. If that is the case, that should have been your answer to "blue".

As it is, with the input blocked, and somehow I can get the normal
amount of cooling to the motor iself by whatever mean, the motor will
run continuously for its designed service life -- because it is not
putting out more heat than it is designed to and not running faster
than it is designed to.

You are right I am just surfing the web for information, and I have
came across several cases where the motor is outside of the conditioned
air stream without seeing one that does it differently. You are
welcome to post your own link.

If they are in the conditioned air path, I would have to wonder why it
was done that way. Certainly the motors themselves are quite rugged and
can operate at a temperature far exceeding that expected in the air
handler. They have small internal fans and have no problem at all
dumping heat into the air even in a hot attic. Why cut down the
cooling efficiency of the whole system by, in effect, using the
evaportor to cool the motor.