Connecting an autonomous heater (Audi Q5-8R)

An indication. Depending on the vehicle design and the engine, a non-return valve can also be integrated into the coolant circuit. Through this check valve, a certain amount of coolant flows back through the small circuit to the engine, even when control signals are applied to the shut-off valve of the coolant supply of the heater "N₂79". After replacing the self-contained heater, make sure that the new self-contained heater adapts correctly. When replacing an autonomous heater with the number 8K0 xxx xxx, 8R0 xxx xxx or 4H0 xxx xxx up to the index "A" with an autonomous heater with the part number 4H0 xxx xxx starting from the index "B", it is necessary to activate the adaptation for the control signal of the circulation pump "V55" using the control unit add. heating system "J364" in the climate mode of operation, installation (for an autonomous heater with the number 4H0 xxx xxx, starting from the index "B", this function is disabled). If "V55" is displayed on the control panel and the climate display, the Climatronic control unit "J255" from "J364" is not activated for certain vehicle versions (depending on the engine and production period) you can report faults due to low or insufficient heating power. If in cars in which the manufacturer has installed an independent heater with the number 4H0xxxxxx, starting with the index "B" (installed since 2012 MY), "V55" is activated by the request "J255" from "J364", this can also lead to a complaint.

Connecting an independent heater to a car without a check valve

Note: The "arrows" indicate the direction of coolant flow. When the heater coolant shut-off valve "N₂79" receives control signals, (e.g. in autonomous heating mode). When the coolant is not warmed up and the ignition is off, the coolant is sucked in by the circulation pump "V55" directly from the heat exchanger of the climate control system.

I 1. Autonomous heater; 2. Return line of coolant to the engine. Connection of the air conditioning system to the engine coolant recirculation circuit; 3. Heater coolant supply shut-off valve "N₂79"; 4. Heat exchanger climate control system. Connecting the climate control system to the engine coolant circulation circuit; 5. Coolant flow from the engine. Connecting the climate control unit to the engine coolant recirculation circuit; 6. Circulation pump "V55". The circulation pump "V55" is connected to the hose harness of the independent heater.

Connecting an independent heater to a car with a check valve

Note: When the heating coolant shut-off valve "N₂79" is operating (for example, in the autonomous heating mode, with the coolant not warmed up and the coolant ignition off) The coolant is sucked by the circulation pump "V55" directly from the heat exchanger of the climate control system. If the shut-off valve of the heating coolant "N₂79" is not working (for example, when the coolant is warm and the ignition is on) The coolant is supplied from the climate control unit heat exchanger back to the engine.

II 1. Autonomous heater; 2. Heater coolant supply shut-off valve "N₂79". In autonomous heating mode, the used additional heater "J364" is controlled; 3. Heat exchanger climate, installations; 4. Return coolant line to the engine; 5. Coolant flow from the engine; 6. Circulation pump "V55", connected to the hose harness of the independent heater; 7. Check valve. A smaller diameter element for throttling the flow of liquid. Depending on the engine, it is installed in the water drain box or engine compartment. Through this check valve, when the engine is running and receiving control signals from the heater coolant supply shut-off valve "N₂79", the coolant flows back to the engine through a small circuit. This connection between the heat exchanger supply pipe and the return line to the engine is installed on vehicles with a built-in check valve; 8. Check valve. A smaller diameter element for throttling the flow of liquid. Depending on the engine, its installation location is in the water drain box or engine compartment. Through this check valve, when the engine is running and receiving control signals from the heater coolant supply shut-off valve "N₂79", the coolant flows back to the engine via a small circuit. This connection between the return line to the engine and the return line to the independent heater is installed on vehicles with a built-in check valve.