What was found
PDX FLIGHT NR 2311, FLIGHT COMP PACK HOT CAUTION LIGHT ILLUMINATED ON PUSHBACK. MAINTENANCE PERFORMED FAULT RETRIEVAL IN CDS, FOUND FAULT CODE 3701 (FD COMP OLT TEMP) IN HISTORY (RECENT) C/W Q400 FIM TASK 21-60-00-810-816, STEP 1-4 AND 5A(D). REMOVED AND REPLACED BOTH LT AND RT OUTLET TEMP SENSORS IAW TASK 21-51-91-000-801 AND 21-51-91-400-801. REMOVED AND REPLACED ECS ECU IAW MM TASK 21-61-01-000-801 AND 21-61-01-400-801. OPS CHECK GOOD. C/W OPS TEST OF THE ECS TEMP CONTROL IAW TASK 21-61-00-710-803. OPS CHECK GOOD. NO FURTHER FAULTS OR CAUTION LIGHTS NOTICED. AIRCRAFT RETURNED TO SERVICE.