2004 3.0 ac delay

[Marine6531]

Hey gents!
I know there are a lot of threads on here about ac but I have read through nearly all of them and the ones that actually sound like my problem never come to a conclusion. So basically Im writing this to see if anyone can help me out becuase this ac issue is frustrating me!

Okay, so the ac doesn't begin to blow cold for about 15 mins after the vehicle starts. I looked first to the aux fan as most posts here point you in that direction. I noticed the aux fan does not spin when turning on ac, even when hitting the MAX button. the compressor however comes on as soon as ac is pushed. About 15 mins later however, the aux fan starts to spin and ac is cold. I checked V at fan and found a steady 14v, DME wire was around 40MV or so. So voltage is getting to the fan at all times. Also if I unplug the pressure switch the aux fan kicks on immediately and is on like super speed! So it seems like both fan speeds work (hi/low). But what else tells the fan to kick on or would cause the fan to not come on until the car is hot. Ohh, I forgot to mention that as soon as it works, you can turn the car off and on and it will still work. Once the cars sits for about 3-4 hours the ac delay starts all over again. I know there is a coolant temp switch, should I try shorting that out and see of it kicks the fan on? Is there any switches/sensors I can try? Relays?

Also, does this years model have a hi/low fan switch outside of the aux fan itself. I was told that the switch that interpretd the DME was actually built into the fan and if it went bad you had to replace the whole fan? But I have also read something about there being a mode switch near the expansion tank, which one is it?

If I have left any important info out please let me know. I will be monitoring this post closely as I am extremely desperate for a solution. Thanks in advance for any/all help!

[pcotangco]

Had the same exact issue on my 06 3.0. I traded it in before I had a shop look into it.

[bigwave2255]

mine does similar, takes about 3-5 km before the a/c kicks in, i have found though that opening all the windows and sun roof seems to speed up the process.

im of the opinion that its a sensor thing, it wants all the hot air out before it starts the a/c up

[g300d]

Gone though this myself and did a lot of research on this.

It is the compressor, specifically the variable displacement control valve at the back plate of the compressor.

Theoretically it is possible to replace the valve if you can find one, but since my compressor overall had seen better days I just replaced the entire compressor assembly.

[Marine6531]

Really, I never thought it was the compressor because it seemed to be working, though it was a fan coming on issue because when it worked the ac is freezing. Not questioning you, just want to understand the logic, how does variable displacement control vavle affect the aux fan? the system in general? Thanks for the response!

[g300d]

I understand how you feel. I felt the same before I understood how the BMW AC system worked. I talked to a lot of techs and waded through a lot of vague info on-line to get a basic understanding of the system.

The E53 X5 AC system uses a variable displacement compressor. That means it does not depend on the compressor magnetic clutch engaging and disengaging a fixed stroke compressor to control refrigerant temps...a mechanical control valve inside the compressor senses pressure differential of inlet and outlet pressure within the compressor and alters the compressor stroke itself for optimal compression.

This kind of system has the compressor clutch engaged all the time as long as the AC is on and there is refrigerant in the system. This threw me off at first as I always assumed an engaged magnetic clutch means a working compressor. In these variable displacement compressors, this is not always true.

Do you have access to gauges? Hook them up and you will notice when the AC is cold, the low side pressure will be in the 30-40 range. When the AC stops cooling you will notice the low side pressure rising. And all that time you will notice that the magnetic clutch remains engaged.

In a standard fixed stroke compressor, no cooling plus elevated low side pressures indicate a worn out compressor. It no longer compresses the refrigerant. It indicates low/loose compression.

In this case it cant be a worn out compressor as there is good compression as evidenced by the cooling and verified by gauge readings. It just happens to be intermitent.

In variable displacement systems intermitent compression usually means the control valve is not working as it should. There is no compression when there should be compression.

The fan is not working because the pressure switch that turns it on does not see any pressure in the system, because the compressor is not compressing...the fan operation is a symptom and not a cause.

When the compressor starts compressing, pressure rises in the system and the fan then operates normally.

I hope that made sense.

[Marine6531]

Makes perfect sense! Thanks so much for the response. Finally I feel like I'm getting somewhere. Surprised there are not more posts of this type of situation? I hope that replacing the compressor is a reasonable DIY'er.
Do you happen to know if I change it myself, are there any other parts that I need to or should be changed at the same time (belts, o'rings, etc)? Thanks again brother!

[g300d]

No problem at all, glad to help!

Yes, I am surprised I did not find any technical info on this problem in any BMW forum I went to.

I found more info on this problem in a Chevy forum somewhere, of all places.

Dont worry, it is a pretty reasonable DIY, a half day or so job.

Nothing really needs replacing along with the compressor unless during the pulldown you notice any worn or broken parts.

I'm having a hard time posting now, this page keeps closing while I type a reply, will post an outline of the job in a bit.

[g300d]

I watched the tech do the compressor replacement and it was not all that hard.

First off you will have to go to a shop to evacuate and collect the refrigerant, otherwise you will have to dump it to the atmosphere, which is bad according to the EPA. .

My tech removed the cover underneath the front bumper so he could work from the top and bottom.

There is a rubber pipe from the engine to a cannister behind the headlight, looks like an EGR thing, which you should remove. The compressor was removed from the top so this line was in the way.

Remove AC belt, the belt tensioner is leveraged out of the way by inserting the appropriate sized allen wrench into the front of the tensioner pulley and just pushing the pulley in the appropriate direction.

Then you can unplug the harness and start removing the block fittings on the compressor.

Then you can start removing the compressor mounting bolts.

Then move the AC lines out of the way and you can pull the compressor out.

As mentioned it came out from the top.

Pretty much reverse to install.

Do take a look at your belts and the system o-rings while you are at it. I just re-used all of mine since they were still in good shape.

I think the 04's use a Calsonic Kansei CSV 717 compressor, the earlier models use a Denso. My 04 3.0 had the Calsonic.

[Marine6531]

Thanks again brother, I'm gonna give it a try! I will make sure to post any relavent information after the job.