Thermostat location Car heating system fails to warm up. What is the problem likely to be ??

More than likely the thermostat.

check the thermostat

You are correct in your suspicions.
The thermostat blocks flow thru the radiator to help the engine warm up. The coolant still flows thru the block with the thermostat closed. If you remove the thermostat the cooling system should flow thru the radiator and stay below 160 degrees if the air temp is below 90.
If the thermostat is out and the engine is getting hot at idle speed, either the water pump has failed, or there is another blockage in the engine block.

Air in cooling system? Blockage? Thermostat failing? Collapsed hoses. there are many reasons why this problem exists. Hot coolant passes through your heater core which is generally located on the firewall of the car. If hot coolant does not circulate into the heater core, it will not pick up the heat and your car heating system will blow cool air. Coolant circulation is most likely the underlying issue. Your water pump may also be failing.

heater core is cloged needs replaced

Hi if your talking about the thermostat in the engine then this has no fuse its a mechanical part that opens when the engine reaches a certain temperature when this part fails it usually causes the engine to over heat

might be time for a new thermostat,

There are several reasons for no heat. 1st, how is the temp gauge in the car? Is it in the normal range, or is it running cold or hot after warming up? How long does it take to warm up? 1st check the coolant level, make sure it is at the correct level, bleed system to remove any air (bleeder bolt usually located near the thermostat housing.) If that checks out ok, and the engine is not warming up, change the thermostat. If you still have a problem, the heater core may be plugged up with rust and sediment. Flushing the system may help to restore the flow of coolant to get the heat going again. Worst case scenario, system plugged beyond flushing out the crud, heater core would have to be replaced. Start with the easy stuff 1st, hopefully that will work. Good luck

It may be a couple of things, first before you replace the water pump, you need to warm the car up, and locate the thermostat houseing, it will have two hoses attached, and one will go to the radiator, and it will be on the engine, after you locate it, warm the car up, after it is warmed up, feel the hoses going too and from the thermostat houseing, if they are both warm, then it is not the thermostat, if they are not both warm, then your thermostat is junk, cheap fix, and easy to replace. let me know, and i will help you from their...........

no bleeder ,remove the radiator cap, start car,see if you are cirulatilng good!!
if not replace the waterpump and thermostat!!!
fill system completly up run with the cap off till it reaches operating temp
then make suure the system i s full ,then its burped put the cap back on your done!!!