Drip sound under dash

[DMurphy]

My 2005 Silverado makes what sounds like drips upon startup. The sounds are coming from unser the dash. Doesn't do it all the time. It sounds like water dripping on plastic. Wondering if I have a drain clogged somewhere and if so where it is?

[Bad Bowtie2]

I would say either your heater core is about to go out OR the AC case drain hose is clogged (if your running the AC).

 

What maintence has been done to the cooling system? Flush, coolant change, etc?

[DMurphy]

I don't know. I just bought the truck. The sound is intermittent and seems to do it most at startup with or without ac running. I don't smell anti-freeze. I'm not 100% sure its a drip, that's the best way I can describe it. Kinda like a tapping sound on plastic.