Our church has a new pipe organ blower, and are considering having the motor converted from 220 to 110. I have explained what is happening electrically, but what is the end result mechanically? Will the motor run differently?

I suppose I should know this, but it's not getting through my thick skull.

the motor should run at the same speed,the amp draw will double though.why change it?

Haligan, the only thing that will change is that the current will double. Which means it will operate at a higher temperature. As far as shaft output nothing will change.

Why are we changing it. (the pretty short version)

The blower was originally installed in the church basement. Back in 1965 pipe organ blowers for a medium size or larger organ were pretty loud. The blower had ductwork that ran 2 stories up and fed the bellows which in turn feed the pipes.
But they remodeled the place and removed the blower without telling anyone, remodeled the room and now it has to be installed in the choir loft. In the loft, there is only 120.

Now I have to have them send me the nameplate figures from the blower and the size of the feeder, because if the amps are going up, it's going to exceed the 80% capacity of that circuit.

DC10,
While the current on the branch circuit that serves the motor will double, the current in the motor windings as well as the temperature will remain the same. The current in the windings stays the same because the widings are in series for the high voltage and in parallel for the lower voltage. The actual voltage and current in each winding is the same using either voltage connection.
Don

The higher voltage is useful in keeping the wire size down and compensating for voltage drop. If for example the blower was closer to the distribution and now in the loft has moved a further distance from the panel then you might have a few new issues. Starting the blower will be harder and may pull the voltage quite low. If the run current for the motor is over or near the max for the wire size you could also be running into low voltage problems caused by those variables. You could shorten the motor life by running at a constant undervoltage. On the other side the motor may now be oversized as the air column may have lower air resistance.
Now that the organ loft has only the one source to feed the organ I guess the branch circuit is now useless for choir lights or any other 120 volt need since it will be fully loaded when the organ is running.
Maybe the better choice is to run the 220 volt circuit and maybe the person responsible for the renovation may become the wiser.

Thanks all. I have a good feeling for what needs to be done. My old church is 5000 miles away. It's hard diagnosing from a distance.

If there is a 120v home run in the loft, you could change the breaker and receptacle to a 240v circuit. (Assuming the wire is sized correctly and no neutral is required.)