It took 3 flights to get to Cancun. After pulling a last minute packing-all-nighter, we flew from Cincy to Philepdelphia to Miama where we boarded our plane and were forced to wait 2.5 hours with no A/C while they determined if the plane was flyable. Right about the time when people started to angrily abandon the plane and fights with flight attendants were happening regularly, we were finally told to get off the plane and await further instructions. We boarded another flight an hour later. Still no-go on the A/C.