As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
APPROXIMATELY 8000FT AND 70NM SSW OF IAH, CREW ENCOUNTERED ICING CONDITIONS AND SWITCHED ON DEICE SYSTEM. IMMEDIATELY DEICE TIMER LIGHT ILLUMINATED. CREW CONTACTED SOC VIA IAH OPS RADIO. DISPATCHER AGREED, RETURN TO IAH. THE FLIGHT LANDED WITHOUT FURTHER INCIDENT. REMOVED AND REPLACED DISTRIBUTION VALVE.