E53 aux fan delay
 

I own a 2005 X5 e53 and can't figure out why when I turn my ac on it won't cool down until after I have driven for a good 10 minutes when the aux fan finally comes on. Sometimes I can get it to start faster by revving the engine but not always. The battery also has a dead cell if that helps figure it out. I checked all of the fuses and they're good. I also have the AC charged with freon to a bit over 35 psi.

If you have a bad battery cell why dont you replace the battery and start your analysis from there. These BMWs are very finicky when it comes to electronics especially when you do not have a properly operating battery.

v8 or I6 engine?

I'm surprised it even starts with a dead cell.

Mine recently gave out as well, was intermittant at when at idle, and then when driving the AC would finally get cold.

A few weeks later it just stopped working altogether and I had to replace it.

I went with the original BMW one and it was pricey, HELLA makes a kit for our cars that's in the $300 range from Turner Motorsport, while BMW is around $550.

its a v6 engine. I'll replace the battery and see if that solves anything. I'm pretty sure the bad battery is the cause of a few other strange problems im having, but I haven't heard of it affecting the AC.

It's either a straight 6 or a V8. No V6's in the E53's.

Ah you're right well its a 6 cylinder

Your compressor is going bad. My 2005 X5 had the same issue when I bought it.

Here is a link with details on it :

BMW X5 Air Conditioner Compressor | Crowz Nest


The variable displacement compressor is worn out basically. I had never ran into one of these and I had done hundreds of a/c systems over the years.

The symptoms are a delay for the air conditioner to start cooling and the aux fan delays too since it runs off the pressure sensor for the a/c system.

The delay starts out small from 2 minutes to 10 minutes. Mine had made it to an hour or more before it would start cooling. Once it ever starts it works fine till you let the car sit for a long time. Usually overnight.

Easiest way to diagnose that its the compressor vs the fan itself is it will cool right off the bat with a bad fan then go hot and not cool again till you get up to highway speeds. Well as right off the bat as any bmw does. I haven't seen one yet that cools instantly on the first start of the day even when new. Takes about 30 seconds for it to get "happy" at cooling.

If its the compressor it wont cool at all until x amount of time elapses. As the compressor gets worse over time the delay will get longer and longer for it to start cooling. Sometimes reving the motor up gets it going. Reving the motor up will not get a bad aux fan going.