1998 Jeep Wrangler

First thing to check is make sure you have the coolant topped off. Alot of times the coolant is just low and not circulating properly. If ok, next check the hose going to the heater core. A good check is with a lazer temp reader. This would tell you if the thermostat is opening all the way. If thats good the hose coming out of the heater core should be hot also but just a little cooler than the input hose. Next I would take the hoses off and try and blow through the heater core, it may be restricted which can cause a drop in temp. Try these ideas and then get back to us. Thanks Curt