What was found
AT CRUISE ALTITUDE, RECEIVED LEVEL 3 MANIFOLD NR 1 FAIL ALERT. AIR SYS ISOLATED PROPERLY AND ALERT WENT AWAY. DIVERTED AND LANDED WITHOUT INCIDENT. R & R LT WING MANIFOLD FAILURE DETECTION PRESSURE SWITCH IAW. MM36-23-03-4. PERFORMED TEST IAW 36-23-03. R & R (2)EA CLAMPS ON LT WING ANTI ICE VALVE IAW MM 30-11-02-2 PERFORMED LEAK CHECK AND OP'S IAW 30-11-00-5 NO LEAKS NOTED. AS A PRECAUTION R & R MANIFOLD FAILURE DETECTION THERMAL SWITCH AT SLAT TRACK NR 3 ON LT WING IAW MM 36-23-04-2 PERFORMED ADJUST AND TEST IAW ABOVE REF AND 36-10-02/501 ACFT OK FOR SERVICE.