Fan has a problem, probably a bad fan clutch.
If you can spin it easily when the engine is off it is most likely bad.
Most common problem is that the blend door is stuck or broken.
it is clogged
You have to replace the thermostat it is stuck open. I would say. Do you have heat when you are driving? I Have the same problem and is trying to fine where it is located. It is usually at the top of the of the motor but not on my 2005 jeep.
Cold Heat - 1989 is rated/received certificates of: UK:15
Boys in Heat was created in 1989.
Eat the Heat was created in 1989.
The Heat of the Day - 1989 - TV was released on: USA: 30 September 1990
The Heat of the Day - 1989 TV was released on: USA: 30 September 1990
because heat core was removed?
My understanding is that it is a single core radiator. If you Have the inline 6 engine, they can generate plenty of heat. Also, a fairly common problem is the fan motor can fail for several reasons. This would make more sense, since it only happens in traffic. Pop the Hood, and let it run until the motor is at about 180-200°f. If the fan doesn't kick on, then you Java narrowed down the problem.
OK, did the blower motor actually just stop, or does it still blow but no heat?
Start with replacing the thermostat, it may be stuck open.