Blown fuse, defective blower motor resistor pack, defective blower motor, or defective fan speed switch.
Pull out on the light switch when you have turned it to the right to turn on the lights.
You haven't even told us what's wrong with it
could be thermostat or heater fan if you can hear all the speeds on the blower motor working then it could be your thermostat but your heater core might be plugged as well
Check for a blown fuse.
Check your fuses!
It could be the cooling fan swith, the water temperature sensor, or the cooling, (radiater), fan motor. It can allso be a loose electrical connection or a blown fuse.
Try taking the car in for a rad flush. You may have a restriction. Check also that the hoses are not kinked, block heater and rad.
The wrong anti-freeze could cause the water to freeze in the engine. The wrong anti-freeze could cause abnormal corrosion in the radiator.
either a bad fan switch or a bad blower motor. Take it to a trusted mechanic.
Replace your heater selector switch
the heater core could be stopped up, or could be low of antifreeze, or the thermostat could be stuck open
your heater is more than likely to be working at night, but simply retain the temperature rather than increasing it. a solar cover will assist this. Are you running the pool pump at night too. Pump not working nothing works.