2004 3.0 ac delay

Marine6531 · #1 05-21-2012, 11:38 AM

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 · #2 05-21-2012, 11:57 AM

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

bigwave2255 · #3 05-21-2012, 11:22 PM

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 · #4 05-22-2012, 07:44 AM

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 · #5 05-22-2012, 10:26 AM

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 · #6 05-22-2012, 11:53 AM

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 · #7 05-22-2012, 01:11 PM

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 · #8 05-31-2012, 12:59 AM

Maybe you could leave the car overnight with the indy so he can see the problem first hand in the morning?

g300d · #9 05-31-2012, 01:24 AM

Here is a good article on variable displacement compressors and a description of the problem:
http://www.aircondition.com/tech/get...9WYWx2ZXMucGRm

Marine6531 · #10 06-11-2012, 07:07 PM

So the starngest thing happenned. I was just ready to make an appointment with my indy when.... my car wouldn't start. I got a jump and it started immediately. I figured i must have left an interior light on or something. I drove around for about 2 hrs and turned it off. 3 hrs later it wouldnt start and i needed a jump again. I went to have the battery tested and they told me it was bad, not enough CCA (they didnt tell me the number it did have). replaced the battery and everything worked fine.

Next day I start my car and within two minutes ac is blowing cold!. it has been two days in a row now and ac is working without any long delay. still takes 2-3 minutes but not 15. and doesnt blow steaming hot air even when not fully cold. Could a low battery have caused my ac issues? is this possible?