As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER TAKEOFF AT CYYZ EMERG PRESS AND ACM OVERHEAT LIGHTS CAME ON. RETURNED BACK TO AIRPORT AND LANDED AT CYYZ. CABIN/COCKPIT TEMPERATURE CONTROLLER REPLACED WITH OVERHAULED UNIT + TESTED SERVICEABLE IAW C-560XL MM CH 21-61-00 + CH 71-00-04.