1. Blower of vehicle heater is switched off and stationary heater fuel metering pump (Y23) not delivering
- No further cycling noise, combustion has finished
2. Heater unit run-on starts approx. 120 seconds
- Circulating pump (A6m1) and combustion air blower (A6m2) continue operating
- Operating noise
- Air flow which is slowly cooling down at exhaust gas outlet
3. Heater unit run-on finished
- Circulating pump (A6m1) and combustion air blower (A6m2) are switched off
- No operating noise
- Noticeable lack of air flow at exhaust gas outlet