Insufficient Heating or Defrosting

Insufficient Heating Or Defrosting Diagnosis (1 Of 2):

Insufficient Heating Or Defrosting Diagnosis (2 Of 2):

The most likely causes of insufficient heating outside the heater system include a low coolant level, faulty thermostat, partially or fully clogged heater core or hose, obstruction to air circulation, or an air leak past a faulty seal into the passenger compartment. For an organized diagnosis procedure refer to the table shown.