No Heat!

I have an 88 Cougar 3.8L V6 that runs very well, but the heater does not work well until the car has been running a very long time (hours). I changed the thermostat, and topped off coolant levels in the reservoir and radiator. The temp gage on the instrument panel stays at cold then jumps after ~30 minutes of running to near the hot side then settles to mid range from then on. In checking the radiator core hoses, what seems to be the output hose stays ice cold. The engine is not leaking coolant. I read the past thread about heater problems, this seems different.

Sounds like a heater core problem. They can get clogged up with sludge and junk that flows through the cooling system. If you have had everything else checked and the car does not overheat, replacing the heater core could solve your problem and give you some heat. I'm pretty sure of it.

I say heater core I had the same problem with 95 4.6