Citation Excel (C560XL)
Flight Crew Air Transport Pilot (ATP)
Aircraft Equipment Problem Critical
Flight Crew Landed in Emergency Condition; Flight Crew Returned To Departure Airport; General Declared Emergency
Aircraft; Weather
During takeoff roll above 70 knots; we had an ACM overheat. Takeoff was continued as briefed in safety briefing. ACM overheat with Master Caution and Emer Press activated during takeoff roll was identified and canceled. We declared an emergency with Tower remained in pattern with no issues. Due to high aircraft density airport; extreme heat entering cockpit and excessive chatter on radio we landed with priority. Short segment checklist was completed in pattern per SOP. Upon landing; abnormal checklist was completed and we returned to [FBO]. Passengers were briefed in pattern and a full briefing was given to them on the ground of our operational procedures. Assistant Chief Pilot and Maintenance were called and recovery Aircraft was within 30 minutes.There was extreme heat in ZZZ this day; temperature on the ground was 105F. APU had run for 45 minutes and cabin and cockpit was cool. I don't see a way I could have avoided the ACM overheat. I followed our procedures to the best of my ability and got aircraft on the ground safely.
Almost immediately after rotation; the cabin pressurization spiked and the Emergency Bleed Air kicked in; causing a significant increase in ambient cockpit noise levels; an immediate increase in cabin temperature; and a very strong and somewhat pungent 'hot' odor. I began reviewing the Emer/Abnormal Checklist for the associated annunciators as well; but flight time was so compressed that we postponed completion of them until we were on the ground. At some point; the Emer Press and ACM Overheat lights extinguished; but I do not recall when.  However; I believe they were out by the time we landed and exited the runway as I remember telling ATC our situation had 'stabilized' just prior to landing.
CE-560SL flight crew reported ACM overheat on takeoff on a very warm day.  They ran the procedure; declared an emergency; and returned to departure airport.