Electric Heater AFN: Parameters & Control Logic

Hi everyone,

I hope I'm in the right subforum.
I'm looking for some information about the switching conditions for the electric auxiliary heater (3 glow plugs in the engine cooling circuit, VW, AFN, 3B2, MJ98, 5-speed, manual climate control).
They are probably only connected to the engine control unit with a 3-stage switching system.
Could someone provide me with some information about the conditions that must be met for the heating system to activate, or how the overall heat management of the auxiliary heater works?

Thank you very much for your help.

Hi,
The dependencies include:
- Outdoor temperature;
- Engine temperature;
- Charging status.
Please refer to the forum rules for further questions. You are looking for information about the MSG and need diagnostic software for it.
hg
Herbert.

Hello everyone!

In my opinion, for this basic information, diagnostic equipment is not mandatory.

The AFN's MSG stores the temperature of the intake air temperature sensor when the engine is started.
If the measured temperature is below 5°C, either one or two, or one plus two, heating elements of the auxiliary heater are activated. The latter depends on the generator load, which is also transmitted to the MSG via terminal DF.
The cut-off temperature of the auxiliary heater is variable and depends on the measured starting temperature of the intake manifold sensor: The colder it was at the start, the longer the auxiliary heater remains active.

Best regards from Passau!