Water Dripping Under Dash

Your drain hose is probably clogged.

 

Have to raise the front of the car, remove the aluminum panel located between the front wheels (it should have a round hole, about 1 1/2" dia., with the A/C drain hose leading out of it). You may be able to clear it if you just snake a stiff but somewhat flexible wire through it. Just don't puncture the evaporator by pushing too much.

 

I doubled over some safety wire and cleared the tube with it. It's pretty long, so I may have had about 12-18" of wire up there. I did not need to jack up the front. I drove the right tire up on a 2X8 and that raised it enough so that I could reach under there and thread the safety wire "snake" up the tube. Water poured out of there. I have not had any trouble since I cleared it.

 

This happened to me, with my 77 GTB. I went through 3 power audio amps, ruined by dripping water, before I figured it out:

My blower/coil assembly's plastic body (mounted just above the passenger's shins in the dash) had a crack in it, and was dropping a fair amount of condensation down into the passenger footwell when running the A/C.

I ordered a replacement from GT Cars in Arizona, and problem solved.

The plastic body on these assemblies are cheaply-built, and 3 decades on, are prone to cracking...

Hope you find the issue....
Greg

 

If you remove the end panel in the passenger footwell you'll see it. Have a look at pictures 4 & 5 in this post:

http://www.ferrarichat.com/forum/showpost.php?p=139755472&postcount=1

Its the tube with the white writing on it, top left