Problem with heater blowing cold

Also, besides coolant level, the heater core may be restricted and the temp blend door may be inoperative .

Heater coil

Stuck thermostat maybe?????

you will have to get a dye injected into the system or have it checked witha freon probe

jtg

This could be a serious problem. Check your coolant level, then check the rear heater lines that supply coolant to the rear heater. They run under the van, over time they rust and leak. Because it is under and to the rear of the van it is hard to notice, i.e. coolant puddles and smell. But please note that this engine has aluminum cylinder heads and does not take kindly to being overheated.

Location of components...

most likely, replace thermostat .

Your thermostat is either defective or your cooling fan is not engaging on the right tempertures (sensor)

goodluck

To check if it is the thermostat run the car and when the temp starts going up turn the heat on full blast in the car. If the temp goes down after you turn the heat on than it is your thermostat.