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First check the water level. If the water level is low or very low, you may have air in the radiator. If you have a small leak, you will have enough water to cool the engine but not enough to heat the heater core. Adding water to the radiator may not be enough. Air in the heater core equals no hot air in the cabin. This problem is so bad in some engine configurations that some cars go as far as to actually have a 'bleeder' at the front of the engine, by the upper radiator hose/thermostat housing (Dodge, BMW, etc.). The heat selector lever/ switch in the cabin may be defective (electrical) and may not open the hot water valve enough, or even be disconnected (mechanical). Some (Ford and foreign cars) use vacuum to operate the valve and those lines may be cracked, worn, pinched or just leaking. You could also have a clogged heater core. These are 3 possible items you could start with, in that order. The thermostat could be At Fault, but this is a give away. If the thermostat is stuck open or missing and you drive the car for a distance, the engine will take a while to warm up then overheat, and the cabin heat will follow the engine temperature. If the engine overheats, you need to take care of that motor more than worry about the heat in the cabin. As you said, you're not asking what to do with your overheating car. You would have taken care of that motor by now and taken care of your heater problem with it.
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Why does your heater not blow out warm air?
if the heater does not blow out warm air change the setting.
Heater on but not blowing warm air?
heater on at idle and will not blow warm air. when moving it blows the warm air from the vents. what will cause this
What would cause the heater on a 1997 Grand Am Gt to not warm up completely and only blow slightly warm air?
It could be the thermostat on the engine. If the engine does not warm up adequately the heater will never blow hot air.
Why is your heater blowing out warm air in your 1990 buick regal?
Isn't a heater supposed to blow warm air?
Why would cold air blow out when you turn on the heater?
engine not warm, low coolant, or stuck thermostat
Can a thermostat cause your car's heater to blow warm air?
Yes.
Why would a heater blow cold air at an idle and warm air while driving?
Low on coolant. Stuck open thermostat. Poor circulation (plugged heater core).
Why would the heater in a 2000 neon blow warm air but never get hot?
Faulty thermostat. Plugged heater core. Temp blend door malfunction.
Why would your heater blow cold air?
Your thermostat is most likely bad. It controls the flow of warm water into your heater core which warms your air. Its a common problem in winter and an easy fix.
What would cause a 2003 Buick Century's heater to blow cold air when idleing but will blow warm air when moving?
Probably need to add antifreeze. Check the Radiator not the overflow tank. If you are low on antifreeze it will not circulate through the heater core.
What would cause the heater to blow only cool to warm air not hot air in a 2004 Chevy Impala?
It could be that you need coolant or it's low.
What would cause a 98 dodge 1500 4x4 heater to blow luke warm air?
Any heater that only blows luke warm air isn't getting warm or hot water to the coil. This sounds like a problem with the thermostat not closing, and allowing the engine to heat the water properly for the heater.
