After driving a half hour when I stop truck it smells like hot rubber under hood

w8t not yet first make sure the coolant is filled in the front left under the hood usually that is the problem if not get back to us

One way to tell a bad thermostat in a car is if the car overheats frequently even if there is water in the radiator.Stuck open - no heat from heater, temp gauge hardly moves off of cold.
Stuck closed - overheats engine, temp gauge quickly climbs to hot.listen for any rubbing, grinding, or whining noises from the pump. look under water pump while running, if pump is going bad. water will come out of weep hole on the bottom of the pump. good-day!

Oil leaking onto the exhaust. Poor ignirtion switch connections causin ghe switch to overheat.

sound like AC COMPRESSOR clutch bearing going bad causing locking up putting drag on drive causing drive belt slip giving a burn rubber smell.

After you start the car.. check the temp gauge.. if slow to move or stays cool.. you have a stuck thermostat.. as in stuck wide open.. needs replacement.

This also means it takes a very long time if ever to have warm air inside the passenger compartment as the engine never warms enough (during cool weather) to provide hot water to the heater core.

However if the temp gauge reads a proper operating temp.. and you cannot get warm air inside.. you have a control issue with the passenger compartment heating system.

A faulty thermostat will also result in poor performance and poor gas mileage.

Have this checked immediately.. if it were to stick closed suddenly (unlikely) your car could overheat.

This part is not very costly.. labor.. depends on which engine is in this car could take up to an hour to an hour and a half.. they may want to do a coolant flush and replace the coolant.. check belts and hoses while under the hood.

Best of luck

thermostat

No heat usually means low water level in radiator. Check your plastic surge tank to see if is at the proper level. When engine is cool check actual level in radiator.

For smell check to see if any oil is weeping from top engine gasket and dripping onto exhaust manifold, You should be able to check with flashlight while engine is idling.

If the temperature gauge looks good (under 3/4) its all good. If not, then there is a problem. If it smells hot inside, like moist and humid you will need to replace the ac filter, that can be located under the hood, close to the water resevoir, you will have to pull the ruber type gasket that is on the edge of the hood/wiper cover.

Let your engine warm up with the rad. cap off and see if the coolant level drops. and make sure your overflow is full. It blows cold air because there is no water getting to the heater core. And it shows a normal(ish) temp because the water needs to be touching the temp. sensor. I really do think there is air in the system and there is not enough coolant but hard to tell from here. Also as with overheating any time make sure to check your oil and look for any coolant as the head gasket seldomly holds together if the motor overheats.

If you smell coolant then there is a small leak, it is most likely the water pump shaft seal, look for stains, coolant leaves a white powder when it dries, look on the underside of the hood for any coolant stains from it been flung there by the spinning water pump. Also have a radiator pressure test run, good insurance aginst an engine overheat if leak worsens, engines are very expensive to repair if overheated badly.