'93 T/A Heater Not So Hot
 

For the past several months the heater in my '93 T/A has been getting less and less hot. It now puts out barely warm air. I don't see the usual looking water control valve in the heater hose line that the Chilton's manual mentions.I don't know what controls water flow in the heater hose. I don't want to start with pulling the heater core. Is there an easy way on this car to check water flow to the heater core.The air outlet controls all work, and the A/C is good.Water temp is within spec. Just no heat at the air outlets. Thanks in advance.