Heater Output

Symptom:-

Heater emits cold air.
1. Engine running: Check coolant valve opens as a temperature control is moved from COLD.
2. Check for engine running cold. See COOLING SYSTEM, Fault diagnosis, Engine Runs Cold
Engine Runs Cold

3. Check heater pipes and hoses for blockage or restriction.
4. Check heater matrix for blockage or restriction, flush system.

Heater emits warm air.
5. Engine running: Check coolant valve closes when both temperature controls are moved to COLD.