This is my first post on here. I have a 1997 Cadillac DeVille with a great air conditioner. Only problem I have is: when the air is on, occasionally black bits of what looks like foam insulation blows out. When you touch this stuff it is like grease. Very messy. Has anyone ever heard of something like this? Does anyone have any suggestions as to how I can clean these vents out? Thanks in advance.

 

2 things come to mind..


The bits are indeed "Foam Insulation" from around the vents. if so it will dissipate on its own.

OR.....

MOLD.....

In the case of the latter, your GM dealer will have a bottle of stuff to pour into the fresh air intake in the Cowl. It may take a while , but it does work.

 

foam will not be greasy. i work with all kinds of foams daily.

one of very much so forgotten a/c maintenance procedures is to shut a/c off 1st, then run blower for a minute or 2. then turn everything off.
reason being, a/c, esp in humid areas, condenses lots of moisture on heat exchange radiator. so you need to dry it off before shutting down blower, or MOLD will just love it.
i think GM will charge you for this. i had several cars in TN that developed a "rotten potatoe" smell from vents. i simply used arm and hammer odor killers, lysol works well too, had blower turned on to max, a/c to max, and sprayed it in via cowl. worked fine.
i'll put spray bottled stuff over spray canned one, lasts much longer, and it takes time for it to get sucked deep enough into the vents.