REVERSE SENSING NOTED BY CPR FLC AS THEY ATTEMPT AN ILS TO YIP RWY 23L. AFTER SOME CONFUSION THE ACFT IS VECTORED BACK FOR ANOTHER APCH. FLC CORRECTLY JUDGED THAT THE TWR CTLR HAD SET UP THE WRONG ILS FOR THEIR APCH.

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INBOUND TO YIP WE WERE NW OF THE LOC FOR ILS RWY 23L APCH ON AN EASTERLY HEADING TO INTERCEPT THE LOC. THE HSI INDICATION WAS WRONG FOR OUR POS AS THE CDI NEEDLE SHOWED THAT WE WERE SE OF THE LOC; WHILE WE WERE ACTUALLY NE. WE WAITED FOR THE NEEDLE ON THE CDI TO CHANGE PRESUMING WE WERE TOO FAR TO THE NW TO GET A GOOD SIGNAL FOR A CORRECT DISPLAY. HOWEVER WE DID RECHK THE LOC FREQ TO MAKE SURE IT WAS CORRECT. WE THOUGHT THERE WAS A CHANCE WE WERE GETTING A REVERSE SENSING INDICATION ON THE HSI EVEN WITH THE CORRECT COURSE SET IN ON THE HSI. FINALLY THE NEEDLE CTRED AND THEN MOVED FULL DEFLECTION TO THE NE SHOWING WE WERE SE OF COURSE. THE ACFT HAS A GPS; A KING KLN90B APCH CERTIFIED WITH A MOVING MAP DISPLAY THAT WE WERE USING TO BACK UP OUR POS ON THE APCH. WE HAD CARRS FINAL APCH FIX INDICATED ON THE GPS SO WE HAD A GOOD REF FOR OUR COURSE. THE TWR CALLED AS WE WERE TURNING W TO CORRECT OUR COURSE EVEN THOUGH THE LOC NEEDLE SAID TO TURN E. THE TWR CALLED AND SAID WE WERE SE OF THE LOC AND AT THAT TIME THE LOC NEEDLE WENT FROM FULL L (SE) TO FULL R (NE) DEFLECTION. WE STATED TO THE TWR THAT SOMETHING WAS WRONG AS WE TURNED WBOUND TO RECAPTURE THE LOC. THE TWR MADE A STATEMENT TO THE EFFECT THAT THEY WERE CHANGING SOME SWITCHES AND THAT ALL SHOULD BE OKAY. WE DSNDED FROM 3000 FT TO 2500 FT AS WE WERE ABOVE THE GS TO TRY AND CAPTURE THE ILS BUT BY THIS TIME WE DECIDED WE DID NOT TRUST THE LOC EVEN THOUGH IT HAD CTRED; WE JUST FELT UNEASY. WE STATED TO THE TWR WE WERE NOT SURE IF THE GAUGES WERE SHOWING US THE CORRECT DISPLAY. THE TWR GAVE US A 230 DEG HDG AND TOLD TO MAINTAIN 3000 FT. WE TOOK THE HEADING AND CLBED TO 3000 FT. THEN WE WERE GIVEN A R TURN TO 360 DEGS AND SENT BACK TO APCH CTLR FOR ANOTHER APCH. ON THE SECOND APCH ALL NAV GAUGES FUNCTIONED CORRECTLY (NORMALLY) AND WE COMPLETED THE ILS RWY 23L APCH. THE APCH CTLR MENTIONED THAT MAYBE THE TWR HAD TURNED ON THE ILS RWY 5R APCH FOR A MOMENT. THAT IS OUR CONCLUSION AS TO WHY OUR GAUGES WERE READING AS THEY WERE. WE HAD REVERSE SENSING AS WE WERE SWBOUND NE OF THE ILS ANTENNA FOR RWY 5. FORTUNATELY NO OTHER TFC WAS AFFECTED. THE TWR SHOULD NEVER CHANGE ILS APCHS WHILE AN ACFT'S TRYING TO USE ONE.