Thermostat is stuck open, not allowing engine to reach operating temp. Replace the thermostat. could also be your heater core needs cleaning also check your rad cap to make sure that it holds the pressure
If your question is more "why" and not what to do: Your engine gets hot and needs to be cooled. To do this there are coolant passages throughout your engine and they connect to your radiator which uses outside air to dissipate the head from the coolant before returning back to the engine. Your water pump circulates the coolant through the system. Your thermostat is like a door that holds the coolant in the engine back until it's hot enough to go to the radiator to be cooled. If it is stuck open the coolant will be continually circulated through the radiator and continually cooled... it will not allow your engine to "warm up"... all it is doing is preventing your coolant from getting up to operating temperature when it's stuck open. the way your heat works is it has a heater core, a mini radiator, under your dashboard. it has coolant running through it and when you turn your heat on it blows air through this heater core. if your thermostat is stuck open then your coolant won't be allowed to get hot so it won't be hot when it goes through the heater core with the fan blowing through it.
A malfunctioning thermostat can cause your temperature gauge to go up and then allow the gauge to go all the way down. When the thermostat is stuck closed, your engine will overheat and water will not get to your heater core. When the thermostat opens the engine cools down and water flows to the heater core.
The engine thermostat controls the flow of coolant to the radiator , it allows the engine to warm up before the thermostat opens in order to limit the maximum operating temperature.
check for coolant in system...radiator..next check for heater core leaking and verify if your thermostat is working(if it opens when engine is warmed up...hope this helps you..L
The water pump will pump coolant(antifreeze & water) through the engine after the thermostat opens up.
If your engine thermostat sticks open it will run cooler on your temperature gauge and you won't see the temperature gauge go up to the point where your engine thermostat opens and then the temperature gauge will show a drop in temperature , your check engine light will probably come on , your gas mileage will be less , the heat from your heater probably won't get as hot If the engine thermostat were to stick in the closed position your engine will overheat ( but there are several other causes for an engine to overheat )
the water continues to cycle through the water pump, radiator, and heater core until the engine reaches sufficient temperature to open the thermostat. when the thermostat opens, cooler water enters the engine block and heads and warmer water is pulled out of the block, enters the radiator to be cooled, and the cycle continues
190 It is dependent on what thermostat you have in your engine. The engine will normally run hotter than the temp the thermostat opens at.
After the engine warms up and the thermostat opens up, some of that heated antifreeze is directed through the heater coil. The MVAC fan blows air over it, and the heat transfers to that air, then it's directed through the ducts.
Check that the heater valve opens fully, and then take the heater hoses off the at the water pump and flush the heater core with the garden hose in both directions.The problem could also be the thermostat being stuck open, meaning the engine is not reaching its operating temperature, especially if you are in a cold climate.
The thermostat is a device which blocks the flow of coolant through the radiator until the coolant inside the engine reaches a certain temperature, at which point the thermostat gradually opens to allow enough coolant though to maintain the engine at its optimum operating temperature. The thermostat then controls the flow of coolant to keep the engine at that temperature irrespective of engine load and operating conditions. Without a thermostat and engine warms up more slowly and will never reach its optimum temperature. This causes increased fuel consumption and increased wear on the moving parts. The thermostat also make the heater work much quicker in winter
when your coolant in your engine gets a certain temperature,usually 180 degrees,your thermostat opens and your coolant circulates through your radiator and it keeps your engine cool so it wont overheat.
A Thermostat enables the engine coolant to heat up quicker. One of the advantages is that the vehicle heater will get hotter faster. When the temprature of the engine reaches about 92 degrees f the thermostat opens to allow the engine coolant to circulate to the radiator which maintains a safe temprature for the engine to run at. A vehicle will run without a thermostat fitted. But it is not recommended on some engines as it may cause a hot spot which could cause the head gasket to blow. A typical example being the Leyland O series engines from the 1970s