I am only getting luke warm air temp from the heater in my 87 D150. The volume is fine just the temp. What should I look for? I had replaced the thermostat a few months ago as part of a coolant flush. Thanks

Hi. I have not go trough something like this, however one first check would be if the heater is not blocked (more frequent in newer cars, but who knows how much dirt it has inside). Could you touch it? is it hot? If not, drain coolant, replace with water, unplug one hose, check for flow.
Also, depending on how new is the car/truck you might have a valve opening/closing flow to the heater (I think)... that has to be checked too.

my 2 cts...

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/6 Dodge Charger 69
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MOVE THE TEMP CONTROL LEVER quickly from hot to cold. Listen for the door to "hit" at the end of the movement of the lever. If it does not "thunk", adjust the cable. Also since you did a cooling system flush, the heater core might have trash in it. Try removing the hoses from the heater, and using a garden hose, flush the core in both directions. I do not recommend using air pressure, as it might burst the core. Also check and make sure the hot water valve is opening all the way. They can malfunction and restrict flow.

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Charrlie_S
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