A320 FLT CREW HAS FAILURE OF THE AIR DATA REF UNIT DURING CLB; ACFT REVERTS TO ALTERNATE LAW AND STALL WARNING OCCURS. FLT CREW DECLARES EMER AND DIVERTS FOR LNDG.

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20 MINS PRIOR TO DEP HAD ADR #1 FAULT INDICATED IN THE SWITCH AND ON THE ECAM. NOTIFIED MAINT CTLR WHO CONTACTED CONTRACT MECH TO TROUBLESHOOT SYS. MECH WENT THROUGH TROUBLESHOOT; RESET AND TEST SENT BY MAINT CTLR. TOLD MECH THAT THERE WAS WATER IN STATIC PORTS FOUND ON PREFLT FROM WASH THE NIGHT BEFORE. MECH SAID THAT WOULD NOT CAUSE FAULT. HE RESET SYS AND SIGNED OFF THE WRITE-UP. ON TAXI OUT; SYS FAULTED A SECOND TIME. CONTACTED MAINT CTLR AND RETURNED TO GATE. MECH SWAPPED ADR #1 TO #2 POS FOR MEL RELIEF. HE RETESTED ADR AND DID LLM CHK. AFTER DOING DDG PROCS; ENGS WERE STARTED AT GATE TO CHK FOR FAILURES AT MECH'S REQUEST. MEL WAS ADDED TO NEW RELEASE. FO #3 WAS SELECTED ON AIR DATA SWITCH; ADR #2 TURNED OFF AND CIRCUIT BREAKER FOR ANGLE OF ATTACH #2 (N-9) PULLED AND COLLARED. FLAPS #3 TKOF PERFORMED IN ACCORDANCE WITH MEL PROC. AT 3500 FT AFTER FLAP RETRACTION PASSING GREEN DOT (210 KTS); STALL WARNING SOUNDED; RED BARBER POLE JUMPED TO 230 KTS INDICATING A FLT CTL DEGRADATION TO ALTERNATE LAW. ACFT NOSE IMMEDIATELY LOWERED AND WINGS LEVELED TO ACCELERATE ABOVE INDICATED STALL SPD. IMMEDIATE CONCERN WAS WHETHER AIRSPD ACCURATE OR NOT BECAUSE OF PREVIOUS FAILURE OF ADR. AN IMMEDIATE CHK OF CAPT'S PFD WITH FO'S PFD AND BACKUP AIRSPD ALL SHOWED THE SAME AIRSPD. ECAM MESSAGE CAME UP 'FLT CTL ALTERNATE LAW-PROTECTIONS LOST.' THERE WERE NO FAILURES INDICATES ANYWHERE! A LIGHTS CHK TO SEE IF WE WERE MISSING SOMETHING TURNED UP NOTHING. EMER WAS DECLARED AND DISPATCH WAS CALLED WITH MAINT CTLR FOR HELP. COMPLETED ECAM AND COM. HAD LONG DISCUSSION WITH MAINT CTLR WITH NO DEFINITE REASON FOR THE FAILURE. DECIDED TO DIVERT TO ZZZ2 FOR RWY LENGTH AND UNCERTAINTY ABOUT NATURE OF FAILURE. EVERY TIME ACFT TURNED; STALL SPD JUMPED TO 240 KTS. REVIEWED MEL TO RECHK PROCS ACCOMPLISHED ON GND. REVIEWED COM DIVERT PROCS. PLANNED FOR APCH TO LONGEST RWY AT ZZZ2 AND REQUESTED CFR EQUIP. LOWERED GEAR AT 2500 FT; TURNED OFF AUTOPLT TO SEE IF THERE WERE OTHER FAILURES. DIRECT LAW WAS ACTUATED BY GEAR EXTENSION. UNEVENTFUL TOUCHDOWN. HAD RESCUE CHK FOR PHYSICAL DAMAGE TO ACFT AND TAXIED TO GATE.