Disconnect the mass wire of the battery, move the heater tap control handle to the right and drain the coolant from the engine cooling system. Removing the instrument panel (see sect. «Removal and installation of the instrument panel»). Remove the cooling system air filter (see sect. «Removal and installation of the air filter»). Loosen the clamps securing the inlet and outlet hoses to the heater pipes and disconnect the hoses. Unscrew the two screws securing the heater pipe seal and remove the rubber seal from the bulkhead.
Unscrew the four nuts securing the heater from the passenger compartment and remove the heater assembly with the controls along the studs; when unscrewing the fastening nuts, the mass wire is removed from one of the studs.
The heater is installed in the reverse order. After installing and connecting the hoses, fill the cooling system with liquid and check the tightness of the connections.