Commercial Glass Door Deadbolt Unlocking Itself

No, you aren't imagining things when you show up on Monday morning and your front commercial glass door is unlocked and there has been no apparent burglary. The Adams-Rite deadbolt, or the generic equivalent, is a laminated steel bolt that usually swings upward into the locked position when you turn your key. When you lock this lock, you should flip your key hard at the end turn and listen for the "ker-plunk"! You want to hear that bolt banging into position and you want to hear it deadlock.

If you find that the bolt is unlocking itself but you aren't quite sure, you can perform two tests.

1. Lock the door and check that the bolt is locked. Grab the outside handle and rattle and shake the door as if you were trying to open it. Watch and see if the bolt is beginning to drop.
2. With the door open and in the unlocked position, insert your key and turn it very, very slowly. You do not want the "ker-plunk". Watch the bolt and listen. As your key nears the final motion, the lock will either "click" into place or fall back down. If it clicks into place, take your hand and try to force it down. If it doesn't fall, then your lock's spring is okay. Retest. If it falls, it needs replacing. Ask your locksmith for the generic brand, which costs the locksmith around $15. If he sells you the Adams-Rite brand, he will pay three times as much and charge you accordingly. 
3. A good price for a standard install of this type might be $95. While you are at it, make sure your lock cylinders are in good shape. If not, have them replaced. A key on the outside and a thumb turn on the inside.