Yes, coolant has to flow correctly for the heater to function.
If the water pump is bad ussually the heater will stop giving hot air .
a bad water pump could cause low heat. The heater uses the coolant from the pump to generate heat.
Yes, the internal parts of the pump can rust, and effect water circulation.
MY CAR WAS DOING THE SAME THING NO HOT AIR COMING OUT OF THE HEATER I CHANGED THE THERMOSTAT. IT WASNT THE THERMOSTAT. I GOT TO CHECKING AND THE SEAL IN THE WATER PUMP WAS BAD. I REPLACED THE WATER PUMP AND IT WORKS FINE NOW.
You probably have a bad water pump or thermostat or both. Is the heater working? If not you have a bad water pump. If it works but is not very warm you have a bad thermostat.
Low coolant? Bad thermostat? Plugged or restricted radiator? Bad water pump? When you turn the heater on you are introducing cooler water from heater core into cooling system.
Low coolant? Bad thermostat? Heater core plugged, restricted or airbound? Bad heater control? Water pump not circulating coolant?
Low coolant level. Open thermostat. Bad heater control valve. Plugged heater core. Bad water pump. An inoperative airflow control or inlet door in the heater ducting or plenum.
If the water pump is driven by the same accessory belt as the power steering pump it could affect the ps pump.
Low coolant? Heater core airbound, restricted, or plugged? Bad thermostat? Water pump not circulating coolant?
The heater core is bad that's why you do not have any heat
Yes. With no hot water circulating, the heater coil/exchanger will quickly cool down to ambient temperature and the fan will blow cold air into the cabin.