White smoke from defrost vents

[UNIMOG-GUY]

I had removed the batteries (for security purposes) on my M1097 A2 and upon reconnecting them white smoke started to come out of the defrost vents. Start switch was in the engine stop/off position. I quickly disconnected the batteries. I noticed that someone (not me as I haven’t used the heater yet) had flipped the heater fan switch to HI. Truck started and runs fine however I’m afraid to turn on the heater. Unfortunately the truck sits in my parking lot at work and is unsupervised when we aren’t open. I have seen several people over the past several weeks stop by to check it out. I can only imagine what happens when I’m not there. I have googled and searched on here with every search term(s) I can think of.

Does anyone have any idea what could have happened?

Thank you in advance!

 

[Retiredwarhorses]

start checking the wires behind the dash and too the heater...

 

[papakb]

This is a perfect application for a trail camera!

 

[glcaines]

I used to leave my truck at work. No problems for about 4 months and then ~$1000.00 worth of damage from vandals. If it was me, I'd take it home.

 

[Milcommoguy]

Somebody snorting coke by the defroster vent during break.
Hold you breath and blow it out with air hose.

HumV gremlins be partying big time and busted, CAMO

 

[Awol]

Somebody snorting coke by the defroster vent during break.
Hold you breath and blow it out with air hose.

HumV gremlins be partying big time and busted, CAMO

You mean take a deep breath.

 

[Coffey1]

Heater core leaking