E53 ac problem

[Kshamm]

Hello,
my Auxillery fan is not spinning anymore and the ac blows warm air but if car is revved to about 2500rpm it start blowing cold air. Is this solely related to the fan not working? Or is it something else aswell?how can I try to power up the aux fan externally to make sure that its the fan that's dead?

Thanks

[upallnight]

You can scan the X and the scan will tell you if the aux fan is bad, or you could look at the fuse in the fuse box for the aux fan and if it is blown then you need a new fan and a new fuse.

There is no way to "Power up" the fan externally since the fan on/off require a signal from the DME. The fan has a direct ground and a direct 12 volt power source to it already. So in order to "Power it up" you must provide this signal to the fan. The fan is not just a DC motor, but includes a controller board built into it. Search posts started by me and you will see a write up on the fan.

[admranger]

If you disconnect the big connector that has the red and brown large gauge wires running to the fan assembly, you can check for 12v to ground (it's always on so you don't even need your key at this point). If you don't have 12v to ground at the connector, you need to chase that (fuse blown or fusible link blown -- 2 different things).

Upallnight has done a lot of documentation on this so look his posts up.

[Motorsport1207]

I would check to see if you have Freon or has it leaked out. A simple check would be to depress one of the nipple on the AC line preferable the low pressure side to see if there is Freon, place a rag over the nipple before depressing.

[upallnight]

Originally Posted by Motorsport1207

I would check to see if you have Freon or has it leaked out. A simple check would be to depress one of the nipple on the AC line preferable the low pressure side to see if there is Freon, place a rag over the nipple before depressing.

Since he is getting cold air when he revs the engine too 2500 rpm, most likely it's the AUX fan and not a low freon problem. At that rpm the mechanical fan is pushing enough air to cool the condenser so the system is working as designed.

[drgeeforce]

I had a similar problem where I got hot air instead of cold, you might want to check the heater control valve, P/N 64116910544.

[Kshamm]

Thanks everyone. Well get to it.