Daewoo MUSSO Service Manual page 739

1F3-8 OM600 ENGINE CONTROLS
Detach line downstream of air admission filter (13).
Vacuum drops.
YES
Fit the line onto air admission filter. Built up vacuum with
vacuum pump. Detach the plug from air admission line.
Vacuum drops.
YES
Go to test step 2.
NO
Faulty thermovalve
NO
Faulty filter with restriction.