I have an 84 vette. One day I noticed that a pretty good stream of water was coming out of the area where coolant lines enter firewall. I am guessing that it is also where heater core is also placed. At first I thought it was sweating coolant lines so I turned off A/C letting the car to continue to idle. The stream turned into a drip so I let car continue to idle checking radiator fluid level the whole time. After a little while I checked again the drip was still there. So i turned heater on let it run a little because with the A/C turned off it started to steam the front window at the defrost ducts. Left heater on checking water level whole time (not much change if any in over flow container) leak still dripping. My question is how can I check heater coil line and unit for leaks w/o taking dash apart to physically reach it? My Haynes manual only told me how to take core out of 85 and up. Hoping 84 is same if I had to change. And the leak is not in floorboard but underneath car.