Insufficient Heating of Passenger Compartment

1. Incorrect operation of controls.
^ The driver should be advised of proper operation of controls.
2. Low engine coolant level.
^ Coolant should be added as needed. A check should be made for coolant leaks. The engine should be run to clear any air locks.
3. Faulty engine thermostat.
^ The thermostat should be checked and replaced if necessary.
4. Kinked heater hose.
^ Hoses should be checked and kinks should be straightened or hoses replaced as necessary.
5. Obstructed heater core tubes.
^ An obstruction usually causes a squishing noise in the core. Any foreign material should be removed from the core or the core should be replaced.
6. Faulty blower motor or blower circuit.
^ Faulty wires or connections must be repaired or replaced. A faulty blower motor must be replaced.