I'm just spending my first winter with my 86 M535i and I'm finding that my heater is not really working.
When I stop there is hot air coming through the top and bottom vents but when I start moving again it turns to just warm air. Not enough to keep me warm though.
I was wondering whether hot air should come out of the centre vents?
It seems to me that there is enough hot air under the bonnet to blow warm air when I stop but when I start moving that hot air is mixed with cooler air coming into the engine bay.
If hot air is supposed to come out of the centre vents is it safe is to assume that heater valve is broken?
Or would it be wise to assume that the heater valve is broken anyway.