I have a Coleman central air conditioner that requires 24hrs at beginning of cooling season, before it will start operating. After that it runs fine.
Is this normal for Coleman central a/c units and if so why?

I never heard of a 24 hour time delay at the beginning of the season or any other time on a residential unit. So I would not consider it normal.

The installation instructions for some air conditioning systems state that the outdoor unit must have line voltage power applied for 24 hours prior to initial start-up. I've never heard of such a thing being necessary on a seasonal basis. That's all I have... anyone else?

I agree, to give the crankcase time to heat up before running. How would you even go about putting a 1 time 24 hr timer on a system? Never seen one here!

Some one is giving you the run around. Your system is made for your comfort if you have to wait to be comfortable that brand would be out of business the first year. I have heard of a fifteen minute wait period with a programmable thermostat before switching from heat to cool or a five minute delay if you switch from heat to cool manually. But never a 24 hour waiting period no matter what brand.

Crankcase temperature switch? 24hr mandatory power to outdoor unit before operating I've seen.