It's not just you and it's not just Hilton properties. Many hotels appear to have seasonal temperature settings which override whatever you set on the room thermostat. Not all staff are aware of this and will try to educate you on how to use the thermostat to cool the room, then are totally surprised that the room temperature goes up instead of down. Occasionally you'll be lucky enough to get an engineer who opens a ceiling panel in the room and flicks a switch to 'cool' - unless the seasonal default temperature is centrally-controlled.