What Causes Normal Coolant Temperature but No Warm Air from Heater?

[DeRicardo]

Possible reasons for normal coolant temperature but no warm air from the heater include damaged water pump impeller or clogged cabin air filter. The specific causes and solutions are as follows: Water Pump Impeller Damage: If the vehicle's water pump impeller is damaged or slipping, it reduces water flow through the radiator, resulting in insufficient heating. The solution is to replace the water pump impeller. Clogged Cabin Air Filter: A clogged cabin air filter or malfunctioning heater control components may cause inadequate airflow from the blower or improper hot/cold air distribution, leading to poor heating performance. The solution is to clean or replace the cabin air filter.