Heater takes forever to warm van on 2005 Chrysler Town & Country

The heater is taking a very long time to warm up the van, all gauges are reading normal. The temp guage isn't rising to fast (or slow), fan motor is blowing, unit switches to/from defrost, no signs of coolant leaking. Not sure how to troubleshoot this problem, any help would be greatfull

first, find the heater hose from the engine block that feeds hot water to the heater core. if this hose is not hot, you have an engine thermostat problem. if the hose is hot, you should be able to follow it to a heater valve, usually at the engine side of the firewall. if this valve is defective, it will not allow hot water from the engine to flow to the heater core. if this valve is working correctly, you may have a "control" issue: a temp blend flap that is not operating inside the evap case, or an actuator problem, or a climate control unit problem or a blocked heater core.