Volkswagen Golf Service & Repair Manual: Bleeding coolant circuit of auxiliary heater

Volkswagen Golf Service & Repair Manual / Auxiliary heater / Aux. heater/heater booster / Coolant circuit with auxiliary heater / Bleeding coolant circuit of auxiliary heater

The removal and installation procedures for the auxiliary heater and the circulation pump -V55- described in this Workshop Manual ensure that only a small quantity of air enters or remains in the coolant circuit. Therefore it is not necessary to bleed the coolant circuit completely after removing and installing the auxiliary heater or the circulation pump -V55-.

However, if a large quantity of coolant has escaped due to another problem, e.g. a leaking hose, or after coolant pipes have been renewed, the coolant circuit must be bled → Rep. gr.19.

After bleeding and filling the coolant circuit, additional bleeding of the auxiliary heater and the circulation pump -V55- must be performed as described below.

Bleed coolant circuit of auxiliary heater.

–	To prevent running dry, fill circulation pump -V55- with coolant.

Note

As only a small quantity of coolant escapes from the coolant circuit during removal and installation of the auxiliary heater or circulation pump -V55- (described earlier), and only a small quantity of air remains in the coolant circuit during installation (auxiliary heater and circulation pump -V55- are already filled with coolant during installation), the system only needs to be bled as described below.

–	Fill coolant expansion tank with coolant as far as upper mark.

–	Activate circulation pump -V55- via final control diagnosis function → Vehicle diagnostic tester in “Guided Fault Finding” mode. This will bleed coolant circuit from heat exchanger in heater and air conditioning unit to circulation pump -V55- additionally.

–	Start engine and choose the highest available setting for temperature (“HI”) on operating and display unit for heater and air conditioning system. On vehicles equipped with Climatronic, turn rotary knobs to “HI” position (for driver and front passenger sides).

–	Run auxiliary heater at full load for at least 2 minutes (circulation pump -V55- is actuated).

–	Run engine at high idling speed (approx. 2000 to 2500 rpm) for at least 2 minutes.

–	Switch off engine and auxiliary heater.

When the engine is warm, the cooling system is under pressure. Danger of scalding due to steam and hot coolant. There is a risk of injury to the skin and parts of the body due to scalding.Always wear safety gloves.Always wear safety goggles.Proceed as follows to release the pressure: cover the cap of the coolant expansion tank with a cloth, and open it carefully.

–	Check coolant level in coolant expansion tank and top up coolant if necessary → Rep. gr.19.

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