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DIY: Do It Yourself
Post here to share or improve your wrench turning skills! All BMW E46 DIY tips, tales, and projects discussed inside. Learn to work on your car and know the right BMW parts you will need!

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Old 05-16-2008, 09:47 PM   #1
tranceasia8
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A/C blowing @ different temps from vents..

I figured that Id get my car ready for summer today and found that my air condition was blowing at different temperatures. The side vents blow colder than the center vents.
I want to see if it was something that i might have missed before I send it to the dealership. Air is set to recirculate, knob is turned to blue, and the a/c button is on.

Does anyone know if could be a door or valve of some kind? I took the cabin air filter assembly out and the small guard/ wall behind the engine and found the box that controls the vents but I dont know what to look for.

Thanks.

Last edited by tranceasia8; 05-16-2008 at 09:50 PM.
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Old 05-17-2008, 01:59 PM   #2
apollotrance1
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I had the same problem, but my passenger vents were blowing hotter than the driver's side. Someone on this forum suggested I get my A/C recharge to fix it, but I haven't had time to take it in.
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Old 05-17-2008, 10:08 PM   #3
tranceasia8
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Quote:
Originally Posted by apollotrance1 View Post
I had the same problem, but my passenger vents were blowing hotter than the driver's side. Someone on this forum suggested I get my A/C recharge to fix it, but I haven't had time to take it in.
ive already had it recharged and still having the same problems.

a buddy of mine said something about a "blender door" ??? dont know wtf he's talking about.
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Old 05-18-2008, 01:52 AM   #4
RB240Z
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Between your center vents there is a turn dial with either red or blue dots. make sure it is on the blue dots. found that out on a cold day wondering why my heat didnt work.
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Old 05-18-2008, 10:54 AM   #5
tranceasia8
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Quote:
Originally Posted by RB240Z View Post
Between your center vents there is a turn dial with either red or blue dots. make sure it is on the blue dots. found that out on a cold day wondering why my heat didnt work.
that was the first thing i checked.
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Old 05-18-2008, 08:25 PM   #6
tranceasia8
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Update**

Ive found that if i either turn on the lower foot vent it makes the air colder from the center dash vents but then then its gets really hot down by my foot.
And if I turn on the upper vent it gets hot by the window.

can anyone help?
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Old 05-18-2008, 08:48 PM   #7
EvilGenius
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There are two common failure modes of "A/C blowing warm":

If you have warm air blowing on both sides and cold air out of other vents your Heater Control valve needs replaced as it is stuck "open" and making the heater function. This is a common failure in our cars. THE HCV is mounted onto the driver wheel well under the air intake bits.

If you have warm air blowing on the passenger side and cold air on the driver side, you have low refrigerant in your A/C loop. Two steps are required here: 1) find out where the refrigerant went. This usually needs a professionally equipped shop to do, then 2) after the leak is resolved, recharge with proper level of refrigerant.
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Old 05-18-2008, 10:26 PM   #8
tranceasia8
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Originally Posted by EvilGenius View Post
There are two common failure modes of "A/C blowing warm":

If you have warm air blowing on both sides and cold air out of other vents your Heater Control valve needs replaced as it is stuck "open" and making the heater function. This is a common failure in our cars. THE HCV is mounted onto the driver wheel well under the air intake bits.

If you have warm air blowing on the passenger side and cold air on the driver side, you have low refrigerant in your A/C loop. Two steps are required here: 1) find out where the refrigerant went. This usually needs a professionally equipped shop to do, then 2) after the leak is resolved, recharge with proper level of refrigerant.
thanks, ill look into those.

any idea if the HCV be the cause of the warm air in the cabin?
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Old 05-18-2008, 10:41 PM   #9
EvilGenius
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Originally Posted by tranceasia8 View Post
thanks, ill look into those.

any idea if the HCV be the cause of the warm air in the cabin?
No because I'm not there, but HCV's are a common failure mechanism, failing open, so there is always heat going. If you have HOT air coming out, then HCV is probably open. This doesn't eliminate A/C problems that could be happening at the same time.

My A/C went out (evaporator coil got leakes), and after that was fixed, the shop found the HCV was stuck too which just amplified the problem.
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Old 05-18-2008, 10:49 PM   #10
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Your mixing valve is spent...easy fix. Check PN 64118369805 on realoem.com

http://www.realoem.com/bmw/showparts...90&hg=64&fg=18

This is defintely your problem
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Last edited by fmzip; 05-18-2008 at 11:00 PM.
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Old 05-18-2008, 11:21 PM   #11
tranceasia8
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Quote:
Originally Posted by fmzip View Post
Your mixing valve is spent...easy fix. Check PN 64118369805 on realoem.com

http://www.realoem.com/bmw/showparts...90&hg=64&fg=18

This is defintely your problem
great thanks.
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Old 05-19-2008, 12:44 AM   #12
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Easy way to check you water valves is to turn on your a/c and grab the hoses going to either side of it. If they are both hot, and your heater is not on...It failed open. If the problem persist, you might have a leak on your evaporator or some other component.
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Old 05-19-2008, 04:47 PM   #13
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Mine's doing this too. I'll have to check this out.
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Old 05-19-2008, 04:51 PM   #14
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If you DIY, make sure you bleed your coolant system.
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Old 05-19-2008, 05:44 PM   #15
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Yeah im gonna need to take mine to the shop to find the leak
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Old 05-19-2008, 05:59 PM   #16
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I had the drivers side cold and the other side warm thing happen to me. After 3 times of adding dye to the freon and not being able to find a leak my mechanic decided to tear the dash apart and see if it was the core. Turns out it was and now a few grand later i have ac
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Old 05-19-2008, 07:02 PM   #17
tranceasia8
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Quote:
Originally Posted by BMWF18 View Post
Easy way to check you water valves is to turn on your a/c and grab the hoses going to either side of it. If they are both hot, and your heater is not on...It failed open. If the problem persist, you might have a leak on your evaporator or some other component.
where can i find these hoses?

Quote:
Originally Posted by fmzip View Post
If you DIY, make sure you bleed your coolant system.
thanks, will do


Quote:
Originally Posted by kurtnhl View Post
I had the drivers side cold and the other side warm thing happen to me. After 3 times of adding dye to the freon and not being able to find a leak my mechanic decided to tear the dash apart and see if it was the core. Turns out it was and now a few grand later i have ac
more info about your problems. just keeping all parts in mind.
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Old 05-19-2008, 10:14 PM   #18
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Quote:
Originally Posted by kurtnhl View Post
I had the drivers side cold and the other side warm thing happen to me. After 3 times of adding dye to the freon and not being able to find a leak my mechanic decided to tear the dash apart and see if it was the core. Turns out it was and now a few grand later i have ac

Yup yup! That's the most common place for refrigerant leak and it's such a PITA to get to, most A/C shops won't bother to crack it open to flood it with a UV light. Apparently that part (evaporator coil) is pretty weak in our cars.
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Old 05-19-2008, 10:21 PM   #19
EvilGenius
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Originally Posted by BMWF18 View Post
Easy way to check you water valves is to turn on your a/c and grab the hoses going to either side of it. If they are both hot, and your heater is not on...It failed open. If the problem persist, you might have a leak on your evaporator or some other component.
To elaborate some on checking your water valve (heater control valve, which controls HEAT): turn your climate control to max cold, a/c on or off, it doesn't matter. down on on the driver side wheel well there is a little round tin can with a connector attached to it with two wires coming out (behind it going toward the cabin are two hoses you can't see. With the engine warm, it should feel ambient warm, not more. If it is screaming hot then hot coolant water is travelling through it when it should not be. To verify, take mental note of the temp of that sucker, then go turn the heater to max hot. The temp should remain relatively the same if the HCV is not functioning properly.

I'm uncertain if this is the actual "bmw method" of verifying if if this is open or not, I call it the poor-man method, because all you need is your hand to diagnose it
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Old 05-22-2008, 12:11 PM   #20
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Originally Posted by EvilGenius View Post

I'm uncertain if this is the actual "bmw method" of verifying if if this is open or not, I call it the poor-man method, because all you need is your hand to diagnose it
Hey EvilGenius, I used your advice from another post and found that test to be actually true. I also talked to a service guy at a dealership and he verified that it's the easiest way to check that part. He also said that valve is a common problem with our cars and that it will certainly override the A/C and blow hot air out of the vents.

So now, I've ordered a new water valve and thermostat (pulled the code the other day) and I'm flushing the system this weekend for both repairs. I'll post back with updates when it's complete.

Last edited by ivanfuzz; 05-22-2008 at 12:13 PM.
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