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.

Could be a bad compressor like Crowz posted or you could be low on refrigerant. In order to diagnose AC problems, you need a good set of manifold gauges. What were the low side reading, the high side reading, and the ambient air temp? Aux fan kicks on when the high side reading exceeds a certain psi. When the Aux fan is running it cools the refrigerant in the condensor which in turn lower the high side reading. Once the high side reading reaches a lower psi the fan kicks off.

This sound exactly like my problem. What would cause the it to delay like that though?

The compressor has two sections in it. I don't know if I covered that in the link I provided or not. If I didn't I will try to add more to it to cover that.

The back plate gets weak causing it to not to push forward like it should (think of it like the fingers on a cars pressure plate on a manual car if that helps) as the compressor gets hot from running it starts working eventually. Also the valve can go bad in the side of the compressor.

I tried replacing the valve on mine first since the valve isn't but $9 or $14 or something cheap like that. But when you figure in the cost of the Freon and the general pain the but installing the valve on a worn out compressor even if it did work its probably better to just replace it. Which I ended up having to do since the valve didn't fix mine anyways.

The time delay is the dead giveway. As long as you can see that the compressor is engaged and turning over like it should and the a/c isn't working at all but does go to working after a long period of time and cools great when it finally kicks in then it is for sure the compressor that is bad. Nothing else can cause that.

Even if the ac is undercharged or anything else it is not going to suddenly start blowing snowballs and working great after a running for awhile.

I wish I had a good link to give you on the great price I got on the compressor I bought. I didn't pay but $115 or something for it. Its over $600 now for some reason. I have no idea why the price when thru the roof from that company.

Great compressor but not $600 worth of greatness :)

I guess I just got lucky that I bought it when I did.