I have a 99 cherokee sport with a 4.0 with no heat. The jeep was sitting for about three months. I put in a new thermostat with no luck. I flushed out the heater core and got some heat but not burning hot. On another post people were talking about a heater valve. In mine, I think that I don't have one. The hoses go straight from the core to the thermostat housing. I did notice that the radiator cap did not get burning hot either. The temp gauge does move. Any ideas or suggestion would be great because its getting cold here.
Thanks

 

maybe it has an air bubble in the system from when you installed the thermostat