Insufficient heat output

Step 1: Fuel pump

Check delivery quantity of fuel pump.

Possible defect Remedy
Delivery quantity too small Adjust delivery quantity
Filter blocked Clean filter
Strainer dirty Clean strainer
Fuel check valve blocked Install new fuel check valve

Step 2: Temperature regulating system

Check temperature regulation.

Possible defect Remedy
Check temperature sensor and temperature regulating switch Replace temperature sensor

Step 3: Engine heat exchanger

Check adjustment of heater flaps on engine heat exchanger.

Possible defect Remedy
Bowden cable adjustment not correct Adjust

Step 4: Engine cooling air housing

Non-return flaps in engine cooling air housing stiff or jammed.

Possible defect Remedy
Not installed correctly Remove cooling air fan and check flaps. replace if necessary.