1991 Cadillac Fleetwood. The heater was working on passenger side but not that warm. Added antifreeze. Seems to be leaking it. Keep adding. gone thru 2 gallons. How do i get heat.

As long as the coolant is full, You won't have problems with heat. Check the rest of the system for leaks. Can't find a leak and still gets low. 2 possibilities. Heater core is leaking or head gasket is leaking. I would lean towards the heater core because of the water inside.

Right hand side (passengers side) behind dash.

A flashing red temperature indicator means your fluid level is low. The 99 beetle takes VW-specific antifreeze; do NOT buy standard green antifreeze for it! Fluid should be added to the round overflow bottle located on the passenger side corner of the engine compartment. Fill the container to the MAX line indicated on the bottle. I use Pentosin Pentofrost SF in mine, available at O'Reilly Auto Parts. As with most antifreeze products, mix it 1:1 with water before adding.

Cars do not normally "use" antifreeze, so if you keep having to add antifreeze, you should check for leaks. Heater hoses or radiator hoses are the most common places for leaks to occur, but the plastic thermostat housing is susceptible to cracking, so check that as well. Otherwise, you could be looking at a leaking radiator or heater core. Worst case scenario would be a leaking head gasket allowing fluid to escape into the cylinders, but that should be suspected only after everything else has been checked. The only other place you would ever see a fluid leak would be a bad freeze plug on the block, but those are very uncommon.

antifreeze smell inside the car.. greenish fluid under the passengers side of the car..inside windows fog up after the car starts up while warming..obvious leaks inside the car on the floorboards..etc..

Is the carpet wet on the passenger side? Sound like you got a heater core leaking.Have fun replacing it.

I wouldsuspect heater hose or a hose of some type. Parts store has a telescopic mirror that could be helpful in lacating where to find the leak.cheaper than pouring anti freeze on the ground

Leaking antifreeze is a relativly easy thing to find. Make sure the system is topped off, open the hood, turn the heater on, and start the car. Once it is warmed up (or sooner if you see the leak right away) check for leaks. My guess is it's comming out of the passenger side. You probably have a bad heater hose. If it is comming off the block it can be a number of things. Identify where it's comming from and get back with me and we can narrow it down.

heater core maybe leaking. easy check is antifreeze or moisture on the passenger side of the car front foot area.

you could have a leaking hose a bad water pump or a bad heater core...its going to be one of those things,,,

passenger side under the dash... tho there is a chance it's mounted on the passenger side inside the engine compartment