[Navcomic]

Hello from the UK.
My wife's B-Max has now got no speeds on the fan except position 4. I have checked the pollen filter - a suggestion on another forum - and that is fine. As the resister pack has been previously changed under warranty, I suspect the resistor pack has burnt out.... again. This problem might be caused by underrated wattage ratings of the resistors in the pack. I have not had the unit out yet to have a look but does anyone know the value of the individual resistors in the pack? I could then try again with up-rated resistors making sure that any additional heat from the resistors does not cause problems with the pack housing.
Incidentally, when the car was last repaired, the Ford agent said we must not run the heater for too long on one speed setting....... 🤣
Thanks for any help.

 

[Gremlin]

a very quick search found this vid that should answer your question and more.

 

[Navcomic]

Many Thanks. I have a feeling this problem is being caused by insufficient air being passed over the resister pack by the heater air flow - especially on the lowest speed setting - with the result the resistor elements burn out. It might also thus be critical as to how blocked the pollen filter becomes over time. I might try running without the filter as I do not want to start messing about with any manifold adjustments. To actually replace the resistors might be possible once I have got a replacement unit, measured the resistor values and then substitute in some beefy discrete resistors based on the wiring diagram from the video or figuring out the circuit before the replacement unit next fails(!). Thanks.