Yet another AC cold driver/warm middle/hot right thread

[haigha]

I've been searching around the site for a while and I see this is a common air conditioning problem. I've read a lot of threads and the Bentley AC section but haven't come up with anything definite to swap out.

2004 4.4 ~24k

I recently replaced the cabin air filter and the FSR--this fixed the problem with no airflow at all.

Both driver and passenger settings are 60 degrees (also tried 70). The ambient temperature is around 90. I've adjusted the dial on the middle vent from 3 blue dots to 1 blue dot and it does not change the symptoms.

Symptoms:

- Air on left vent is cold but perhaps not as cold as it should be.

- Left side of middle vent is cool, not as cold as the left vent.

- Right side of middle vent is warm, perhaps ambient temperature.

- Right vent is about the same as the right-middle vent.

- Rear seat vent is about the same as the other warm vents.

Here's what I've checked so far:

- No codes are being thrown to my CarChip. No Service Engine Soon light.

- R134a was checked by mechanic about three weeks ago at oil change. I don't think R134a has ever been added.

- The glovebox and rear panel fuses are okay.

- Compressor sounds like it is engaging. There is a medium-high pitched pressure sound when AC is turned on, not overly loud. It is masked when the fan is turned up to about half speed.

- Aux fan spins when AC is turned on.

- I swapped the cables on the IHKA (climate) control module--passenger to driver and vice versa--to make sure it wasn't a bad connection. Because of the limited play, it was tough to swap them. I'm not sure if the sensors are further along the line or are in the IHKA itself.

- Cleaned out the vents on the climate control module intakes on the IHKA with a compressed air can.

- Looked and listened for any leaks in the engine compartment. I didn't hear anything but I can hear the compressor working.

My (relatively uneducated) guesses are:

1. Passenger Heater valve (engine compartment, left strut tower according to Bentley).

2. Evaporator temperature sensor. Is this close to the FSR? Perhaps it got dislodged when swapping out the FSR? But wouldn't that affect all vents the same?

3. IHKA heater core sensor. Since swapping the cables didn't have any effect, I don't think this is the case but if the sensor is what the white cap plugs into, maybe that's what I need to swap?

4. A motor / valve is not closing properly on the passenger side. I'm not sure what the most likely candidate is here.

Do you have any thoughts based on your experience with this or a similar problem?

Thanks.

[rph74]

I had a similar issue with an older Mercedes, and it was the heater valve. That is my uneducated guess.

[haigha]

Originally Posted by rph74

I had a similar issue with an older Mercedes, and it was the heater valve. That is my uneducated guess.

Thanks for the feedback. Do you know if that is what is used to switch between the hot and cold air functions? I'm guessing that the passenger side control also controls the rear seat vents so that would make sense.

I had read this thread where a poster said his problem was the "water valve" but I'm not sure if this is the same thing we're talking about on the left strut tower.

http://www.xoutpost.com/bmw-sav-foru...ditioning.html

[rph74]

The valve on my old Mercedes was called a Monovalve. Vehicles such as ours would have duovalves, because they have dual temperature settings (driver and passenger side). I have never looked at ours, but it would either be 2 separate valves, or one duovalve.

Yes, this valve controls heat/cold functions. It opens and closes based on desired temperature. A stuck valve would likely cause hot air to come out--the very symptom my Merc had when I swapped it.

[rph74]

I looked on realoem, and yes the part I am speaking of is called the water valve:

RealOEM.com BMW E53 X5 4.4i Water valve/Water hose IHKA

It is #1 in the picture. Again, it's only a guess, but likely 1 of the 2 valves is stuck. Note that each valve controls one side, 1 drivers and 1 passengers. When mine was bad in my Merc it would intermittently blow hot air only, even if
AC was on. Sometimes it would be fine, then suddenly a rush of hot air would come out.

The water valve seems to be the likely culprit here IMO. Unlikely to have anything wrong with compressor, etc because you wouldn't be getting cold air on one side. It would be hot air all over. A stuck valve could easily overcome the AC system with hot air. I've felt it firsthand.

[haigha]

Originally Posted by rph74

I looked on realoem, and yes the part I am speaking of is called the water valve...

Thank you for the link and the information, rph74. That is very helpful

The Bentley manual calls this the Heater valve (replacement on page 640-13). Unfortunately, it requires draining the coolant. On the plus side, the part is only ~$170.

Edit: BTW, for the 04+ at least, the part number is different. Here is the RealOEM diagram for the N62 engine:

http://www.realoem.com/bmw/showparts.do?model=FB53&mospid=47747&btnr=64_1412& hg=64&fg=18

[m5james]

Originally Posted by haigha

Thank you for the link and the information, rph74. That is very helpful

The Bentley manual calls this the Heater valve (replacement on page 640-13). Unfortunately, it requires draining the coolant. On the plus side, the part is only ~$170.

Edit: BTW, for the 04+ at least, the part number is different. Here is the RealOEM diagram for the N62 engine:

http://www.realoem.com/bmw/showparts...12&hg=64&fg=18

RealOEM doesn't show actually pricing...expect more in the $300-$400 range. I've been able to disassemble and rebuild a few for customers over the years, but there have been some that deteriorated so badly that there was no saving them. These fail mostly due to people using the improper type of coolant, so sediment builds up and clogs up/deteriorates the seals within the valve. Mind you I haven't updated this site in forever, but there are a few pics of valves that I've rebuilt. Boise Bimmer Service - - Kevin - 99 740iL

[haigha]

Originally Posted by m5james

RealOEM doesn't show actually pricing...expect more in the $300-$400 range. I've been able to disassemble and rebuild a few for customers over the years, but there have been some that deteriorated so badly that there was no saving them. These fail mostly due to people using the improper type of coolant, so sediment builds up and clogs up/deteriorates the seals within the valve...

Thanks for the tips.

The part pricing info is reasonably current on RealOEM for this (currently list is around $185). I found it at getbmwparts.com for ~$146.

I have never added or changed the coolant. It's supposed to be lifetime coolant in this vehicle (starting in MY04 for E53, IIRC). [ Edit: the coolant level and rating are checked at every service by my mechanic (roughly annually since I only put on 4k per year, last service in April 2010) ]

However, I'm wondering if it is the heater valve based on Brian's information in this thread:

http://www.xoutpost.com/bmw-sav-foru...nger-side.html

[sprocket1200]

on our 04 3.0, the heater valve was the culprit. trusted indie said it was a common fault. A/C blew icy cold after the fix. as a bonus they also found the rubber air intake boot cracked and replaced that for parts only,

i say do heater valve.

[haigha]

Thanks for the confirmation, sprocket. Do you know if your indie replaced any other parts than the main heater valve? Bracket, grommets, etc. (besides the cracked intake boot). It's great to have a reliable indie