Volvo C30 2007 Service And Repair Manual page 534

NOTE: Mark the internal position of the hoses in relation to each other before removal.
This ensures that the hoses are correctly positioned and not under stress
during installation.
INSTALLATION
INSTALLING THE ENGINE COOLANT HEATER
Position the engine coolant heater in its lower mounting.
Install the fuel line over the engine coolant heater using a new clamp.
HINT: Use: 9512619 to secure the clamp.
Press the top edge of the heater into place.
Install the mounting screw and the bracket for the connector. Tighten. See: TIGHTENING TORQUE .
Install:
the lower coolant hose on the water pump. See the marking made earlier

the connector on the water pump

the exhaust pipe for the engine coolant heater. See: FUEL FIRED BOOSTER HEATER EXHAUST

PIPE (B5244S4)
the radiator hose for the water pump in its holder

the fuel line in the clip below the engine coolant heater

the connector for the engine coolant heater

the radiator hose into the passenger compartment.

Tighten the drain nipple on the radiator.
Fill with coolant and warm up the engine until the thermostat opens.
Top up if necessary.
FINISHING
TESTING THE ENGINE COOLANT HEATER AND INSTALLING THE COVER
2012 Volvo C30 T-5
HVAC Climate Units - Removal, Replacement And Installation