Volvo Workshop Service and Repair Manuals

Install the engine coolant heater. See: Fuel Fired Booster Heater See: Auxiliary Cabin Heater/Service and Repair/Fuel Fired Booster Heater 

Finishing

Final check of the engine coolant heater

Test run the engine coolant heater and check its function. See: Fuel-powered preheater, checking See: Auxiliary Cabin Heater/Testing and
Inspection/Component Tests and General Diagnostics/Fuel-Powered Preheater, Checking 
Check that no diagnostic trouble codes (DTCs) have been stored while the repair was carried out.