As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
APU WILL NOT PRODUCE COOL AIR 89 DEGREES IN CABIN AT GATE. ACCOMPLISHED EXSTENSIVE TROUBLE SHOOTING FOUND LOW LIMIT VALVE TO BE FAULTY. REPLACED LOW LIMIT VALVE PER MM21-51-11. PERFORMED LEAK CHK NO LEAKS NOTED. OP CHECKED GOOD.AC OK FOR SERVICE.