What was found
AT FL 370, GOT AIR SYS 3 OFF WITH ILLUMINATED RED MFG LIGHT. RAN QRH. MOMENTARY LEVEL 3 AIR MFG 3 FAIL WITH TRI TONE, DIVERT. T/S IAW FIM 36-23 ITEM 3, CHECKED PNEUMATIC FAULT IND U1-240 FOUND RT PRESSURE SWITCH TRIPPED. PERFORMED NR 3 MANIFOLD LEAK DOWN CHECK IAW MM 30-11-00-5 AND MANIFOLD CHECKS NORMAL. R & R RT WING MANIFOLD FAIL DETECT PRESSURE SWITCH IAW MM 36-23-03-4. OPS CKS NORMAL IAW EA 8-3622-151147, REF MM 36-23-03-5.