Interesting A/C Problem

Never2Low · #1 09-07-2010, 01:28 AM

Hey guys, long time BMW and Audi owner, new forum member.

I picked up a low mileage 2004 X5 4.8is recently that is in excellent condition. The dealer was able to confirm my suspicions that this SAV was properly cared for by providing me with the records I requested.

Anyway, as with all vehicles, it was obviously traded in for a reason and I am able to sort pretty much everything myself. I am at the end of the list and this one has me kind of scratching my head. I would appreciate some insight, in case anyone has experienced this one before.

My passenger vents were warm when I bought the vehicle, so I immediately hooked up the manifold gauges and ensured pressures were proper on high and low side (I wish I could have recovered the old stuff and done it the ideal way, but paying someone $250 to recover and sell me back my own refrigerant is ridiculous). After doing this, my a/c is colder, but the passenger vents are still warmer than driver.

I tested for heater valve issues, but it seems that is not it. Passenger vents are slightly warmer regardless of vehicle temp or pinched hose. Interestingly enough, the temp difference between driver and passenger vents increases as I roll the mixture dial colder (to three blue dots).

Also, I checked the Final Stage Resistor and it looked good (Appeared to have been replaced before) and ensured the fins were clean. I checked this because the vents do not blow as hard as I deem a BMW should. My 540 vents blew considerably harder, and these seem to talk the talk (Loud) but they fail to blow hard. Rear vents blow weak and warmer as well. I also noticed slight fluctuations in the fan speed periodically (No indication of change on display, it will just go up and down quickly a few times).

So, my main problem is that I noticed a whistling noise coming from my middle vents today. I isolated the noise to the middle-right as the main culprit and it would lessen with the compressor off. However, if I close the vent then I can faintly hear it from the far right (passenger) vent. If I close BOTH passenger front vents then the noise is GONE. Now, here is the interesting part; when I have all vents open and it is making the whistling noise, I can roll the middle mixture dial and it will go completely quiet when I roll to two blue dots or colder and the same is true when I get past one red dot.

So, for some reason the air mixture dial is controlling the noise issue. And, for the record, the dial gets difficult and wants to spring back when I get all the way to 3 blue dots (It bounces back to around two blue dots). This leads me to believe that there is a stuck actuator or flap down in the dash or something that could be causing my warm front/rear passenger vents and dial issues. I also think the FSR could probably use to be replaced.

I apologize for the book, but it is necessary for the experts here to properly diagnose.

Thanks.

PS It is still 110 degrees here (and humid lately) so I would assume that is amplifying my issues.

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Weasel · #2 09-07-2010, 07:45 AM

What were the running pressures?

Never2Low · #3 09-07-2010, 09:53 AM

Running pressures:

Ambient Temperature - Approx 104-106 degrees

Idling, Max A/C for 15 mins

Low Side Before - 37
High Side Before - 250-255

Low Side After - 42
High Side After - 245

Static:
Low - 80
High - 150

From what I have been reading, the X does not typically like above 30psi, but no one seems to be recharging their system in the epicenter of Hell, haha, and I cannot find a matrix from BMW for it. I had my wife give me 1500rpm and the pressures dropped to approximately 26psi low side so I slowly added the R143a and the vents got colder, which landed me around 30psi @1500rpm (equating to the 42psi idling).

Also, from my experience the static pressures should be closer than that. So, I am interested to see what you think of those numbers, and I have a feeling that someone has messed with the system before. In the back of my head I keep thinking that it is needing everything recovered, vacuumed and the proper amount of refrigerant added to cure the temperature difference in each side. There are so many issues that I want to figure out the most efficient way to go about finding the solution (Many different things or one thing causing all symptoms), hoping that someone else has experienced this and can point me in the right direction!

***Keep in mind that these numbers are off the top of my head. I do have them written down at home.

Weasel · #4 09-07-2010, 01:04 PM

Well the numbers are all right around the normal area, and I agree with the thought that it needed some added if the low side dropped to 26 at 1500rpm.

You are on the right path getting it recovered, vacuumed and charged to the proper level. The E53 platform only takes 0.98 lbs of refrigerant and can be temperamental with off amounts. A bit low and the right side blows warmer, a bit high and the evaporator can freeze on highway trips... Good first step is ensuring proper charge levels with most AC problems.

Never2Low · #5 09-07-2010, 01:17 PM

Quote:

Originally Posted by Weasel

Well the numbers are all right around the normal area, and I agree with the thought that it needed some added if the low side dropped to 26 at 1500rpm.

You are on the right path getting it recovered, vacuumed and charged to the proper level. The E53 platform only takes 0.98 lbs of refrigerant and can be temperamental with off amounts. A bit low and the right side blows warmer, a bit high and the evaporator can freeze on highway trips... Good first step is ensuring proper charge levels with most AC problems.

Well that is a relief. Do you think it could use a small amount more as a test before recovering and fully servicing the system? I always err on the side of conservative (and if it ain't broke, don't fix it) so I stopped before I got to a psi level I was not comfortable with.

If you think that it could use a small amount more and that it could cure the difference in temp side to side then I would be happy to try it out.

Also, I am mostly concerned about the noise in the dash that is affected by my wonky mixture dial and the lack of volume from the vents. I think I will order a FSR today as well.

cavx5 · #6 09-07-2010, 07:52 PM

hi...my x5 also has one of the problems you described..when i put the temp control wheel to 3 blue dots it wont hold that position..it will roll back to between 2 blue and 3 blue dots..it almost fells spring loaded because it will roll back..then somtimes it will hold 3 blue dots and after a while it will move to a position btwn 2 and 3

Never2Low · #7 09-07-2010, 08:34 PM

Quote:

Originally Posted by cavx5

hi...my x5 also has one of the problems you described..when i put the temp control wheel to 3 blue dots it wont hold that position..it will roll back to between 2 blue and 3 blue dots..it almost fells spring loaded because it will roll back..then somtimes it will hold 3 blue dots and after a while it will move to a position btwn 2 and 3

Yep, that is exactly what happens with mine. I will be tearing into the HVAC system this weekend to see what I can find anything and to acclimate myself with the E53 system. I will update my findings if no one else has chimed in by then.

Never2Low · #8 09-15-2010, 04:47 PM

Update. I resolved the uneven air temps with a negative terminal pull for 1 hour (I reset the Adaptive Transmission and it made a HUGE improvement, so I wanted to reinitialize the entire vehicle).

The whistling is gone and I still have a little fluctuation in fan speed which I will address soon with the FSR DIY.

I just wanted to make sure this information was up to date for any future issues being able to get resolution with a free and simple fix. My suspicion is that I had sticking flap(s) somewhere that were fixed by resetting the system.

c4racer · #9 09-15-2010, 05:46 PM

Quote:

Originally Posted by Never2Low

Update. I resolved the uneven air temps with a negative terminal pull for 1 hour (I reset the Adaptive Transmission and it made a HUGE improvement, so I wanted to reinitialize the entire vehicle).

The whistling is gone and I still have a little fluctuation in fan speed which I will address soon with the FSR DIY.

I just wanted to make sure this information was up to date for any future issues being able to get resolution with a free and simple fix. My suspicion is that I had sticking flap(s) somewhere that were fixed by resetting the system.

Mr. Gates has conditioned us to always try a reboot first!! I had the fuel pump out on a Mazda recently - replacing the filter sock trying to chase down a surge (turns out it wasn't that btw). And when the pump went back in it was reading 0 fuel level. I pulled that sucker out a couple times and did a ohmeter test and everything and all seemed in order. Then it dawned on me - I should reset the computer. Quick neg batt terminal pull solved the issue. I still cannot figure out how the ECM knew the pump had been removed since the ign was off the whole time it was apart. Only thing I can figure is maybe the pump sends some different signal when power has been cut, but doesn't make a whole lot of sense. But it goes back to the old adage - when in doubt, reboot it!!

Never2Low · #10 09-16-2010, 01:37 PM

Quote:

Originally Posted by c4racer

Mr. Gates has conditioned us to always try a reboot first!! I had the fuel pump out on a Mazda recently - replacing the filter sock trying to chase down a surge (turns out it wasn't that btw). And when the pump went back in it was reading 0 fuel level. I pulled that sucker out a couple times and did a ohmeter test and everything and all seemed in order. Then it dawned on me - I should reset the computer. Quick neg batt terminal pull solved the issue. I still cannot figure out how the ECM knew the pump had been removed since the ign was off the whole time it was apart. Only thing I can figure is maybe the pump sends some different signal when power has been cut, but doesn't make a whole lot of sense. But it goes back to the old adage - when in doubt, reboot it!!

haha, true.

Well, the closest that I can figure is that every time you start the vehicle it does a test (fluid levels, bulbs etc). So, when you pull the battery for long enough it must go into some sort of service mode, assuming that the vehicle is being serviced and re-initializes the entire system in order to accommodate any replaced parts.

Or, it just hates me and a battery pull makes it forget; either way.

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