MD80 CREW FOUND THE R PACK MIXING VALVE WAS STUCK IN THE COLD POS.

Narrative

AFTER DEP FROM LGB; WE DISCOVERED THAT THE R TEMP CONTROLLER WAS STUCK IN THE FULL COLD POS AND WOULD NOT WORK IN EITHER AUTO OR MANUAL. AFTER LOOKING IN BOTH BOOKS AND FINDING NO PROC; WE CALLED MAINT TO TROUBLESHOOT. THEY RECOMMENDED PULLING AND RESETTING 3 CIRCUIT BREAKERS. WE TRIED THIS TO NO AVAIL; AND FOUND WITH OUR HVY PAX LOAD AND KEEPING THE L CONTROLLER HOTTER THAN NORMAL; IT WAS BEARABLE IN THE AFT PART OF THE JET. AFTER LEVELING AT CRUISE; I DECIDED TO TURN ON ALL THE WING AND ENG ANTI-ICE TO SEE IF THIS WOULD DO ANY GOOD. ALMOST AS SOON AS THE WING ANTI-ICE CAME ON; THE VALVE STARTED WORKING; LEADING ME TO BELIEVE THAT THE PRESSURE CHANGE UNSTUCK THE CTL VALVE. I THINK IT WOULD BE A GOOD IDEA TO INCORPORATE THIS PROC WITH THE CIRCUIT BREAKERS AND ANTI-ICE INTO OUR QRH BOOK. SINCE IT WAS A BALMY MORNING IN LGB; THE VALVE; BEING IN THE FULL COLD; WORKED FOR OUR COOLING NEEDS ON THE GND; SO WE NEVER KNEW IT WASN'T WORKING PROPERLY. HAD IT BEEN A COLD/FROSTY MORNING IN WINTER WITH A VALVE STUCK IN THE 1/2 - 3/4 POS; WE MAY HAVE HAD TO DIVERT SHORTLY AFTER TKOF FOR AN UNCTLABLE CABIN TEMP.