What was found
CLIMBING THROUGH ABOUT 16500 THE RIGHT SIDE PILOT NOTICED AN ELECTRICAL ODOR. HAD ALSO NOTICED A POPPING SOUND IN HEADSET AND RECEIVED A CAS MESSAGE WSHLD 2 HTR FAIL ALL ABOUT THE SAME TIME. RAN QRH AND IT DID NOT RESET. CHANGED OUT HIS HEADSET FOR DIFFERENT ONE BUT THE POPPING SOUND REMAINED. AFTER TALKING TO THE FODM DECIDED TO RETURN TO IAD. ON THE DECENT PASSING ABOUT 12000 THE CAS MESSAGE CLEARED & THE POPPING SOUND DIMINISHED TO NEARLY GONE. REMOVED COCKPIT GLARESHIELD COVER PANELS & INSPECTED AVIONICS & AVIONICS COOLING FANS WITH NO FAULTS NOTED. REINSTALLED COCKPIT GLARESHIELD COVER PANELS IAW AMM 25-12-04. WITH GPU POWER & ALSO WHILE RUNNING ENGINES DURING WINDSHIELD OPS CHKS POWERED ON CABIN LIGHTS, COFFEEMAKER, ENTERTAIN ITEMS, LAV & THROUGHOUT MAINT INSPD CABIN ITEMS FOR ANY ODORS OR ABNORMALITIES WITH IAD. NONE NOTED, LISTENED & CHKD AVIONICS BAY IN LT & RT GALLEY WITH NO FAULTS. AFT LAV PARTIONS WERE OFF DURING MX & NO ODORS NOTED THERE WITH LPDU & RPDU. AFTER ACFT ALL POWERED DOWN FINAL WALKTHROUGH WITH NO ABNORMAL ODORS NOTED. CABIN DOOR WAS SHUT FOR ALL CHKS. PER CONTACT CENTER RECOMMENDATIONS AFTER T/S. R & R WINDSHIELD AUX RELAY K0032 IAW 24-65-05. PERFORMED WINDSHIELD HEAT OPS CHECKS IAW AMM 30-42-00. OPS CHKD GOOD.