Q: Temperature gauge says overheating, engine feels only warm. Heater not blowing hot air.

Hi there. From the description you have provided, your vehicle overheating may be a combination of problems. The cooling system work you performed, replacing the radiator, the thermostat, the radiator fan switch and flushing the cooling system, should of taken care of your vehicle’s overheating. It could be, a faulty water pump impeller. From the symptoms you have described. It could be, air trapped in the cooling system. Purging the air can be tricky, sometimes. There is a bleeder screw that helps purge the air. Start the vehicle, with radiator cap removed, heater turned on, open bleeder screw and close when antifreeze come out.

Allow thermostat to open, it may percolate a bit before it opens, once the thermostat opens, accelerate the RPM a few times, check heater hoses for heat on both sides. You should see flow in the top of the radiator if, water pump is working and thermostat is open. Bring up RPM, add antifreeze, and reinstall radiator cap, let engine return to idle. Squeeze the upper hose, if pressure exists, the system is full. It could be, the engine temperature sensor or temperature gauge is faulty. I recommend having you vehicle’s engine overheating be diagnosed and repaired by a certified technician, such as one from YourMechanic.