does the 2000 buick park avenue have a heater fuse?

No your vehicle does not have a heater fuse it has a relay, a big fuse that can withstand more amperage (electrical current flowing through it). Your problem sounds more like the heater core or coil has expired. Does the fan blow but you do not get warm air after the vehicle has reached normal operaing temperature?.

Exactly. Blower widows fine. Just no heat.

Blower works fine.

The heater is a simple device with no moving parts, hot water from the intake manifold enters the copper coil, blower fan blows air across it and out into the cabin. With the blower working fine and no overheating problems two probable cause are eliminated, you have hot water and circulating air. Look for a wet spot in the carpet on the passenger side of the interior. If moisture is present then it is the heater coil that needs replacing, it happens.

I checked that. It appears to be working correctly and freely. Would sensor be bad that would cause this?

Yes.

Where would it be located or what would it be called. Also, is there a way to bypass it for the time being.

unhook your heater hoses and pour both side full of CLR lime and calcium remover and let it set in there for about 20 min.. put one end in a gallon jug and blow air into the other side and you may get a bunch of junk out. Always be careful not to get the chemical on you!!!!!! Have a garden hose handy to rinse any of it away from you and the rest of the car. This is what orange antifreeze does.

Thanks, I am having the same problem as tshell. I will try that tomorrow.