Quote:
Originally Posted by X5chemist
Does the auxiliary fan kick on when the A/C is turned on (when the engine is cold)? I think the auxiliary fand is only turning once the engine is hot. What input to the DME activates the fan? Does BMW use a low/high pressure switch system? Sorry, I don't know how the A/C system activates on an X5. I want the A/C system to start cooling as soon as it's turned on (engine running).
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The DME will kick the fan on at key on to confirm it's functional. If you have somebody else turn on the key you will see the fan turn a bit maybe 1/4 turn.
The AC will engage at engine start if everything is working.
The heater will not engage until the engine reaches some magical temp so it doesn't blow cold air when it's already cold out.
Sounds like you are describing that the air doesn't blow until some time into a drive and that indicates a failure of the FSU or the control hardware. Not likely the blower motor but that is possible.
A 2nd level scanner or laptop with the BMW software will request blower on to test the hardware but from experience, and having my FSU fail a month ago, I would be replacing the FSU.