The first possibility is the thermostat didn't work. To find this out, after the engine is warmed up u check the hoses going from the engine to the heater, they should be hot. if they are hot then the next reason would be a cable to the temp on the heater needs to be adjusted or the heater core is plugged inside or out.
Probably a bad thermostat.
Check the radiator for full coolant. Check the engines water pump and thermostat, as the engine coolant carries heat from the engine into the heater core.
Flush your radiator coolant and replace thermostat
bad thermostat or bad heat gasket
when running the heat-pump the air blowing from the heat ducts is not hot ( it's to cold for the heat-pump). you have a main furnace and it won't turn on ( is thermostat selected for this source), ( is the power switch for main furnace on ), ( is fuse for this furnace good). If these are good (check thermostat wiring at thermostat, and transformer).
Low coolant? Defective thermostat? Heat control cable not adjusted properly? Heater core plugged or airbound?
Vehicle takes an excessive time to attain normal operating temperature Heat not HOT with coolant full - thermostat not closing properly Vehicle heats up too soon - No heat with coolant full Coolant boils out of reservoir or top of radiator - thermostat not opening
check your water or coolant level If coolant level is ok, replace the thermostat.
does the engine not heat up or does the car not blow out warm air when you turn on the heat?If the car is not blowing out warm air when you turn the heat on then you need to check your coolant levels. the heat will turn off if there is not enough coolant in the car.If the temperature gauge shows that your engine is not warming up you may need a new temperature gauge (thermometer)A2. Another source could be that the radiator thermostat is open all the time. This you may easily check by removing the thermostat from the radiator, and checking that it operates by putting it in some water which you bring to the boil.
A heat pump thermostat.
Car not blowing air or heat
heat and a/c barley blowing in back?
try putting anti freeze in it, you may also need a new thermostat
Thermostat stuck open. Replace.
AnswerYup, in most cases. Check the thermostat.
If your windows fog up you thermostat may not register because you heater coil may be broken.
Is your radiator fluid full?
Follow the lower radiator hose from the radatoro to the engine. The lower hose is attached to the thermostat at the engine. Are you haveing problems with the engine warming up but the heat not blowing as hot as it should? Consider the heater core.
check the antifreeze
the ac stoped working and so did the heat . I changed the thermostat added freant
First start would be to check the antifreeze and if that is full then I would check into the Thermostat and make sure it is stuck. If it is Full and heats up real fast then my guess would be the thermostat.
What do you mean by "has no heat"? No air blowing out, blowing out cold air when heater is on, blowing nothing at all? Heater not turning on? What specifically is happening?
Thermostat stuck open, clogged heater core, heater flow valve not functioning, or low of coolant.
Any brand or make will work if it is 2 heat 1 cool thermostat