FLUSHING

1 Most cabin heaters contain a small radiator (matrix), which can be flushed through to remove any silt and corrosion. This can be done in situ (see the Quick Flush steps), or by removing it from the car, then attaching a hosepipe to one of the outlets.

2 If you suspect the heater matrix is leaking, it may be possible to dismantle the heater and extract it to either replace it or have it repaired. The heater matrix can also be pressure tested.