I know this is an old post, but I could not stop jumping in.
The American Airlines 707-123 and -323's with Freon Packs only had TC's on #2 and #3. The TC's were powered by 16th stage bleed air.
On the Climb out, passing FL180, we typically turned on the #4 bleed (9th stage) and #1's in the high 330 or so.
Then at TOD, both bleeds were shut off and left that way since 1 and 4 were brought to idle.