Heater control valve - options?

[ChapterM3]

What's up guys - I searched for this topic but couldn't find anything although I figured this has got to be something people are experiencing

Recently recharged my A/C, car feels amazing with A/C again BUT the driver's side vents are clearly colder than the passenger side vents. They're both blowing cold air, and the freon is for sure all topped up, but the driver's side is just colder than the passenger side vent (in the right of the double middle vent and on the passenger side)

I looked this up randomly and turns out it could be these lovely 20+ year old heater valves on the driver shock tower under the airbox.

Have you guys replaced yours recently? With the OEM part being special order/NLA and M-tax on this double valve is over $450+ I'm looking for other solutions non-OEM -

Found this one for $100, have any of you installed one of these or have a suggestion for a $100 alternative?

https://www.partsgeek.com/cfdq5n4-bmw-m3-heater-valve.html

Part in question - Not my photo below but this is what is in my car: I have the double valve, non-M cars I believe have a single valve -

Thanks in advance!

[Cubieman]

I would be getting a used one off ebay, and you can run the non-M ones in our cars. I think technically you do need to code for for it as to not get an error but it's not like it's going to light up on the dash.

There was a thread years ago about these in regards to CSL airboxes and the extra little space the non-M ones can potentially provide. I think Terra said something about the coding portion of it.

What leads you to believe this is the issue with your cold air being less on the passenger side? That would certainly be much easier to install than a mode door etc.

[maupineda]

E9x chassis use that pump as well as the Z4M so the non M may actually be the same.

[George Hill]

In my experience if the heater valve is open the A/C will not be very cold.

If you want to double check your hypothesis you can measure the temp of the hoses in and out of the valve to see if coolant is flowing. OR you can check the heater core temp with ISTA/INPA.

[ac427]

I'm not sure why a valve that controls heating for the whole cabin would make one side warmer than the other.

[uberchris]

I replaced this part on my car because the pump had failed (threw a code, but no CEL). I originally tried a no-name brand from amazon and that failed within a month. I replaced that with a Vemo from FCP Euro and it has worked well for about 2 years now.

[PSUEng]

I'm not sure why a valve that controls heating for the whole cabin would make one side warmer than the other.

I thought the same, OP may have an HVAC box damper door issue. Like a failed motor.

[ac427]

I thought the same, OP may have an HVAC box damper door issue. Like a failed motor.

I have never that term before. Do you mean motorised vent control?

I did find that there are two cabin temp sensors, part number 64116930015

I think your vent theory is more plausible though.

[Cubieman]

Just a very quick AI type search shows 5 doors and the heater valve part at the bottom is interesting.

[ChapterM3]

Has anyone replaced their heater control valve because of my listed symptom? Has anyone else experienced this? Again A/C on cold and when you put your hand to the left or right vent, for example, in the center - it is noticeably colder on the left vent over the right vent, as in so much so the passenger would complain the A/C is not cold enough

uberchris when you replaced yours I'm guessing you don't recall if your vents had different temps coming out of them?

[Cubieman]

https://share.gemini.google/xMU7gujuH5vx

Maybe see if the refrigerant is low, could use a gauge from one if those off the shelf AC recharge cans if you dont have gauges.

Not sure how accurate this info is in the link but worth looking at if no one has had that specific issue with a fix.

[PSUEng]

I have never that term before. Do you mean motorised vent control?

I did find that there are two cabin temp sensors, part number 64116930015

I think your vent theory is more plausible though.

Yes that's just the terminology I use at work. I'm not intricately familiar with the E46...so I pulled out my trusty Bentley manual (yes, the paper version).

Question for the OP: Is the airflow volume the same on all of the vents? This is purely a temperature issue?

BTW from what I read in my Bentley manual, the water valve is "electrically pulsed to control the flow of coolant through the heater core" and isn't shown in the A/C system diagram although it does have electronic connection to IHKA, likely for the pulsing. So I'm not seeing how that is affecting air temp on just one side of the vehicle.

If you have the same air volume at all the vents, I would ask does the temperature difference follow the air distribution to foot and dash?

[ac427]

Cubieman's post above mentions a slight loss of gas may make the two cores in the evaporator behave differently and therefore cause a temperature difference.