As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ASH FLT 7188 ORD CAE. CREW REPORTED ON CLIMBOUT OF ORD WITH THE R PACK ON MEL, L PACK HI PRESS CAUTION ILLUMINATED ON EICAS. CREW COMPLIED WITH THE QRH WITH NO RESOLVE. CREW DONNED CREW O2 MASKS AND ELECTED TO RETURN TO ORD. CREW DID DECLARE AN EMERGENCY. MX SECURED BLOWN SUPPLY DUCT ON LEFT PACK.