aircon - fan when should it fire up?

[Overboost]

Originally Posted by Blackjetvette97

Hi all,
I am having A/C issues in my '04 X5 3.0i E53. I have pulled all 4 red 50amp fuses under glovebox and all are good(NONE of them are labeled as "AUX FAN" whatsoever). I have a free-spinning aux fan(no binding) got continuity on it(+/-), got 12V reading from power harness to fan, fan does not rotate upon start-up or Max A/C activation or at normal op temp, etc.
Unplugged lower rad hose sensor, fan did not go on.
Is there anything else that is affecting the operation of the fan, causing these symptoms? Do the US non-diesel E53's have this MIDI format fuse wired in? I also have ared/cyan wire in my harness. I am kinda stumped.
Would Final Stage Resistor affect aux fan operation, above and beyond when A/C is commanded on......like upon startup test???

Any help or guidance would be appreciated.
Thanks

Steve

Unplug the high pressure AC switch located in the hard AC line next to the compressor. The fan should spin full speed over a few seconds almost like a jet engine taking off. If it does not spin, chance are the fan itself is bad.

[Blackjetvette97]

Hi all,
Overboost, thanks for the reply. Unplugged high pressure switch and fan roared on, smooth rotation, no bad sounds/smoke!(I did this several times and fan operated every time, but shut down upon reinstalling switch)
So, now I know fan works
Plugged connector back in and compressor sounded like it engaged, but fan slowed to a stop and I assume compressor then shut down again. Is it my switch?
Thanks for help!


Steve

[Overboost]

Originally Posted by Blackjetvette97

Hi all,
Overboost, thanks for the reply. Unplugged high pressure switch and fan roared on, smooth rotation, no bad sounds/smoke!(I did this several times and fan operated every time, but shut down upon reinstalling switch)
So, now I know fan works
Plugged connector back in and compressor sounded like it engaged, but fan slowed to a stop and I assume compressor then shut down again. Is it my switch?
Thanks for help!


Steve

Usually not the switch but at least you have ruled out one of the most common failures (the fan). Time to put some gauges on it and see what it wants.