The ole fan trick.

I don't think a (room?) fan is a big enough load (unless it's a whopper of a fan!) to burn in your power cable. And depending on the capacity of your conditioner, running a big enough load off it to burn in your cable might not be a good idea.

You could just run your amp with your source power cord for awhile or what a lot of people do which is easy and safe is to buy (or make) a little IEC adapter (IEC male to 3-prong AC female) which will enable you to daisy-chain your power cord onto your refrigerator or room air-conditioner power cord. 3 days to a week of that and you're good to go ;-)
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As Nsgarch said and I agree.
I prefer to hook up a power cord to my refrigerator (us an adapter) and let it run for a week to 10 days.

I hook up to a refrigerator also for a couple of weeks....

Thanks guys for your responses...that seems to be the way to go.

I use the clothes dryer with the adapter. It works great!

I use fridge or AC (any heavy load appliance). Seasons the cords quickly. Of course you could use a pure class-A Amp...