autom8

I drive a 1996 Carbriolet 2.8L and I ran my heat for the first time last week and in a two hour drive, the coolant tank ran empty. There was no coolant leaking onto the floor on either side of the car. Also, the windows didn't fog up and I didn't smell any antifreeze. I checked the connection at the firewall of the engine bay and there is no leaking there either. I have yet to get under the car for a good look and plan to this weekend. My question is: Does this car have a heater valve that regulates the flow of coolant when the heat is on? Perhaps it could be failing. If there is no valve, why no leaking when the heat is off? I still need to check the connections to the engine block.

Rusty Spokes

No heater valve if you have manual heater controls. If you have "auto-temp" with a digital display..then you will have a vacuum controlled heater valve. AFAIK most USA Cabriolets had manual heater control.

Heater cores that leak hot coolant will tell you..fog on the windshield or hot coolant on the floorboard.

Get the car up in the air and look around..the coolant went somewhere. See if your local parts store has a pressure tester you can use as a loaner..most do. You may need a specific adapter for the VW/Audi cap..and pressure test the system. If you find a loose hose-clamp or cracked coolant bottle..be sure and bleed the air out of the system. Go by the book.

autom8

Awesome advice. Thanks!