no heat
on 2002 Nissan Altima

I just replaced the sensor and the heat started working just fine now I have no heat again but it blows out cool/warm air

Asked by for the 2002 Nissan Altima
what sensor???

check coolant level, check thermostat and see if the heater hoses are both hot.

did it overheat??? if it did, internal damage may have resulted.

I checked the coolant level and it was low so I added coolant and its warm now but now did not over heat. I changed the thermostat. And I changed some coolant package on the engine.