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E46 (1999 - 2006)
The fourth generation 3 Series (E46 chassis) was introduced in 1999 and set the standard for engineering and performance during it's years of production including being named to Car & Driver's 10 best list every one of those years! ! -- View the E46 Wiki

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  #1  
Old 05-05-2013, 05:05 AM
bfinta bfinta is offline
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Mein Auto: 2004 325xi
strange heater / AC problem

Hi, was hoping someone might have any ideas on what is causing my problem, i've done a search on google and here but not found anyone with my specific issue, i have a 2004 325xi wagon...

When i set the climate control to full "auto" at 16 degrees C (hot day outside), it shoots out hot air ALWAYS from the vents that go to windshield and very cold air going to the dashboard vents. Consequently, if i set it to 16 degrees and manually select my fan speed / and which vents to use, the dashboard vents are not very cold at all and if i select the vents for the feet or the windshield those are also always very hot despite it being hot outside.

Why does it not go as cold when set to 16 degrees with manual fan control vs full auto where the dashboard vents are ice cold yet it insists on blowing to the windshield HOT air.

I have tried already blowing compressed air / vacuuming the little vent on AC control unit. And yes the AC button is set to ON and the outside air temperature readout is accurate.

I can buy a new AC control unit online pretty cheap, any idea if that will solve the problem? Or any other suggestions?
Thanks in advance.
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  #2  
Old 05-06-2013, 10:01 AM
bfinta bfinta is offline
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well just a little update... took the car into the garage today and confirmed that the AC control unit is not the issue and the Freon is ok. but didn't come up with a solution yet... any ideas would be appreciated
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  #3  
Old 05-07-2013, 07:33 AM
Sider Sider is offline
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Mein Auto: 320d E46
Hot water valve blocked open...I had the same problem.
Simply to check: set the temperature to 16 degrees with the engine already well warmed-up.
Touch the pipes from/to the valve to the AC cooler. If the pipes are hot like the main cooling pipes it means that the valve is open and lets the hot water circulate inside the AC radiator.
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  #4  
Old 05-07-2013, 11:48 AM
oswaldr2 oswaldr2 is offline
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I also have that same problem. Sider, did you take it into a shop to have it fixed or do it on your own? How much did it cost?
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  #5  
Old 05-08-2013, 12:03 AM
Sider Sider is offline
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The valve can be blocked open for different reasons.
On my model (320 d) it is very easy to access e remove the valve+pump assembly.
The reason can be mechanical (dirty, a little piece of plastic etc.etc.) and in this case it is sufficient to open the valve and clean . Easy job.
If the problem is electric the matter become a little tricky (malfunction of the AC control unit for example) a probably a diagnostic is needed.
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  #6  
Old 05-08-2013, 03:44 AM
iStarlet iStarlet is offline
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I have a 318i 2002. My valve is blocked shut.
Anyone has a link to some article that explains how I can manually disassemble the valve set and clean it?
Thanks!
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  #7  
Old 05-08-2013, 04:43 AM
Sider Sider is offline
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Look for the number 5 (valve+circulating pump assembly)
Should be very easy to recognize and to reach/disassemble.
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  #8  
Old 05-08-2013, 04:51 AM
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elhombre elhombre is offline
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Quote:
Originally Posted by iStarlet View Post
I have a 318i 2002. My valve is blocked shut.
Anyone has a link to some article that explains how I can manually disassemble the valve set and clean it?
Thanks!
So this means your heater does not get hot. Is this correct? The valve(on mine anyway) is a sealed unit not designed to be disassembled for routine maintenance. That said, take it apart, and write up your findings. I paid about $100 for the part a few years ago and it seemed more cost effective to replace it.
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  #9  
Old 05-08-2013, 07:03 AM
iStarlet iStarlet is offline
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Thanks Sider. I already knew this, was wondering if you have a list of tools, a procedure steps, etc... for this; but it's okay, I'll work with it slowly and figure it out in the weekend.
@elhomber, yes, not a single spit of warm air, everything else with the AC works fine. I checked the hose on my side of the car and they are not as hot as the ones coming into the valve set, so it must be it.
I had a mechanic change the AC blower and fix something in the compressor recently, before that I had hot air but not cold air; now I have cold air but not hot air, oh the irony !!! Need to fix this, condensation on the windshield at night is getting intolerable...

Last edited by iStarlet; 05-08-2013 at 07:05 AM.
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  #10  
Old 05-08-2013, 07:49 AM
bfinta bfinta is offline
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thanks for the replies... ill take it to my mechanic and see what he says. hopefully its not too complicated to fix for him. id try it myself but am quite lost mechanically speaking ill update with any developments.
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  #11  
Old 05-08-2013, 07:58 AM
Sider Sider is offline
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Quote:
Originally Posted by iStarlet View Post
Thanks Sider. I already knew this, was wondering if you have a list of tools, a procedure steps, etc... for this; but it's okay, I'll work with it slowly and figure it out in the weekend.
@elhomber, yes, not a single spit of warm air, everything else with the AC works fine. I checked the hose on my side of the car and they are not as hot as the ones coming into the valve set, so it must be it.
I had a mechanic change the AC blower and fix something in the compressor recently, before that I had hot air but not cold air; now I have cold air but not hot air, oh the irony !!! Need to fix this, condensation on the windshield at night is getting intolerable...
Oh but to check you need cold air outside and to set the maximum temp possible in the AC unit with a hot engine to see if the valve opens.
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  #12  
Old 05-08-2013, 10:22 PM
iStarlet iStarlet is offline
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Quote:
Originally Posted by Sider View Post
Oh but to check you need cold air outside and to set the maximum temp possible in the AC unit with a hot engine to see if the valve opens.
Yes I have this case, especially at night:
Outside very cold (ambient temp sensor is new and working)
AC control temp set to the highest (+32 deg C, I think)

Still no hot air

Is it easy for an average citizen to mess with this thing or I might ruin something?
I have a 318i 2002.
Thanks
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  #13  
Old 05-09-2013, 03:18 AM
Sider Sider is offline
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The reason can be the valve....or an AC control malfunction.
The work can be easy (it was in my case) or difficult, it depends on the cause.
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  #14  
Old 05-09-2013, 04:05 AM
iStarlet iStarlet is offline
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Quote:
Originally Posted by Sider View Post
The reason can be the valve....or an AC control malfunction.
The work can be easy (it was in my case) or difficult, it depends on the cause.
My AC control unit was recently changed, but it was a used part, so there is a chance
We'll see what happens... Thanks for the help !
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  #15  
Old 05-10-2013, 12:27 PM
bfinta bfinta is offline
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Quote:
Originally Posted by Sider View Post
Hot water valve blocked open...I had the same problem.
Simply to check: set the temperature to 16 degrees with the engine already well warmed-up.
Touch the pipes from/to the valve to the AC cooler. If the pipes are hot like the main cooling pipes it means that the valve is open and lets the hot water circulate inside the AC radiator.
So I just talked to the mechanic and he says he doubts my issue is the hot water valve and is likely something defective in the heater box which he says requires taking out the whole dash to get at I was told if it was the water valve I wouldn't be getting cold air at all and that likely something inside is not blocking the hot air
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  #16  
Old 05-10-2013, 12:49 PM
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ahull ahull is online now
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Quote:
Originally Posted by bfinta View Post
So I just talked to the mechanic and he says he doubts my issue is the hot water valve and is likely something defective in the heater box which he says requires taking out the whole dash to get at I was told if it was the water valve I wouldn't be getting cold air at all and that likely something inside is not blocking the hot air
Looking at the schematic posted above, you can set to max temp and see if the hose that returns hot water to the engine from the heater box/core is the same temperature as the hose that brings hot water from the engine.

That will confirm that your heater core is getting hot water THROUGH it. If the hoses after the *valve* are hot, but the return to engine hose is not, either you have air in the system preventing flow through the core, or the core is blocked.

If the return hose gets as hot as the inlet hoses but you still have little/no heat, it could be a "door" inside the vent system that has failed and does not allow air to be drawn over the heater core. See this thread: http://www.bimmerfest.com/forums/sho...844&highlight=
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2003 330i TiAg Sport Pkg
DIY MODS: AA Stage I supercharger, Meyle HD FCAs w Powerflex CABs, Bilstein shocks, Meyle HD Rtabs, Angel Eyes, Clear Corners/Markers w/ LEDs, LED tails, ZHP rims, Akebono pads, AUX input
DIY E46 Merit Badges: Sunroof resurrection, CCV, OFHG, VCG w/ VANOS seals, DISA, Cooling Refresh I, steering giubo, window regs, Magnetic Infandibulator (see wiki)
DIY On deck: Rear Diff bushing. UUC SSK, clutch job eventually, Wavetrac LSD
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  #17  
Old 05-10-2013, 01:01 PM
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ahull ahull is online now
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Scanning through the threads I posted, a couple of other things need to be considered:

1. does your dash show the proper outside temp? EDIT : I see you answered this one as it's working right.
2. you need to vac out the little grille on the climate control panel as it detects cabin temperature. Also, there apparently is a fan that draws the air through that grill that can become blocked/fail and that can cause wacky performance. Have to remove radio and climate control to see the back of it.
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2003 330i TiAg Sport Pkg
DIY MODS: AA Stage I supercharger, Meyle HD FCAs w Powerflex CABs, Bilstein shocks, Meyle HD Rtabs, Angel Eyes, Clear Corners/Markers w/ LEDs, LED tails, ZHP rims, Akebono pads, AUX input
DIY E46 Merit Badges: Sunroof resurrection, CCV, OFHG, VCG w/ VANOS seals, DISA, Cooling Refresh I, steering giubo, window regs, Magnetic Infandibulator (see wiki)
DIY On deck: Rear Diff bushing. UUC SSK, clutch job eventually, Wavetrac LSD

Last edited by ahull; 05-10-2013 at 01:13 PM.
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  #18  
Old 05-10-2013, 01:04 PM
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ahull ahull is online now
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Ugh. That schematic is not correct for a 325. Can you pull up yours on realoem.com for a 325. I think it's same as 330 which would show another hose coming back from the heater core and going to the engine. That is your "return" hose I'm referring to.
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2003 330i TiAg Sport Pkg
DIY MODS: AA Stage I supercharger, Meyle HD FCAs w Powerflex CABs, Bilstein shocks, Meyle HD Rtabs, Angel Eyes, Clear Corners/Markers w/ LEDs, LED tails, ZHP rims, Akebono pads, AUX input
DIY E46 Merit Badges: Sunroof resurrection, CCV, OFHG, VCG w/ VANOS seals, DISA, Cooling Refresh I, steering giubo, window regs, Magnetic Infandibulator (see wiki)
DIY On deck: Rear Diff bushing. UUC SSK, clutch job eventually, Wavetrac LSD
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  #19  
Old 05-10-2013, 01:12 PM
bfinta bfinta is offline
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Thanks for your replies ahull, very much appreciated. yes my dash does show the correct outside temp. Ive also sprayed with compressed air / vacuumed that little inlet thing on AC control unit. My mechanic pulled an AC control unit from another BMW to see if switching that would fix the problem but same problem with a different control unit. As for checking the return hoses, I looked around under the hood and just couldn't figure out what is what. also a lot of the hoses are running near the engine so by default they feel hot to the touch

Last edited by bfinta; 05-10-2013 at 01:14 PM.
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  #20  
Old 05-10-2013, 02:16 PM
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ahull ahull is online now
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Hose 5 is the one you need to check. You would probably need to remove your cabin air intake - not that difficult but you don't sound like the wrenching type. Have you ever put in a new cabin air filter under the hood by the winshield? Unclip the cable holder and pull the cables out, three twist clips for the filter and then 4 torx bolts to remove the drain tray under it. It's simple and straight forward. Have a friend that's mechanically inclined to help in exchange for a ?
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2003 330i TiAg Sport Pkg
DIY MODS: AA Stage I supercharger, Meyle HD FCAs w Powerflex CABs, Bilstein shocks, Meyle HD Rtabs, Angel Eyes, Clear Corners/Markers w/ LEDs, LED tails, ZHP rims, Akebono pads, AUX input
DIY E46 Merit Badges: Sunroof resurrection, CCV, OFHG, VCG w/ VANOS seals, DISA, Cooling Refresh I, steering giubo, window regs, Magnetic Infandibulator (see wiki)
DIY On deck: Rear Diff bushing. UUC SSK, clutch job eventually, Wavetrac LSD

Last edited by ahull; 05-10-2013 at 02:22 PM.
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  #21  
Old 05-11-2013, 08:35 AM
bfinta bfinta is offline
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ok so your saying cable 5 is one of the cables that runs along near the cabin air filter. Yes i've changed the air filter before. Im not so bad at this stuff, its just from these schematics i cant really tell what is what and to be honest looking under the hood i dont even see where this water valve is.

So if im understanding correctly, when the AC is on and everything is working as it should, their should NOT be any hot water going into the "heater core" right?, the hot water valve you speak of should be blocking the flow of water right?
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  #22  
Old 05-11-2013, 10:10 AM
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ahull ahull is online now
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Quote:
Originally Posted by bfinta View Post
ok so your saying cable 5 is one of the cables that runs along near the cabin air filter. Yes i've changed the air filter before. Im not so bad at this stuff, its just from these schematics i cant really tell what is what and to be honest looking under the hood i dont even see where this water valve is.

So if im understanding correctly, when the AC is on and everything is working as it should, their should NOT be any hot water going into the "heater core" right?, the hot water valve you speak of should be blocking the flow of water right?
The only issue about working on these cars and modern cars in general - much less free room under the hood to see/work. The hot water valve is mounted on the driver's side shock tower, about a foot down from the top on front inside corner. Has a little cylinder about the size of a D battery sticking up off it and a hose running on the front side hot from engine and back side inlet to heater core. The core inlet hose from the valve #3 and return hose to the engine #5 both go through your firewall underneath the drain assembly under the cabin filter. Take off the cabin filter and the drain pan below it (4 light gold torx bolts) and you can see it.

Yes. When the AC is on the hose between the valve and the firewall #3 should be cooler than the supply#1 on the front side of the valve. When the heat is on, that hose #3 should be hot, and the return hose #5 running from firewall to engine should also be hot, unless your core is blocked or has air in it, blocking flow.
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2003 330i TiAg Sport Pkg
DIY MODS: AA Stage I supercharger, Meyle HD FCAs w Powerflex CABs, Bilstein shocks, Meyle HD Rtabs, Angel Eyes, Clear Corners/Markers w/ LEDs, LED tails, ZHP rims, Akebono pads, AUX input
DIY E46 Merit Badges: Sunroof resurrection, CCV, OFHG, VCG w/ VANOS seals, DISA, Cooling Refresh I, steering giubo, window regs, Magnetic Infandibulator (see wiki)
DIY On deck: Rear Diff bushing. UUC SSK, clutch job eventually, Wavetrac LSD
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  #23  
Old 05-11-2013, 10:20 AM
bfinta bfinta is offline
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ok so for my issue because im getting heated air AND cold air (hot from defroster and footwell, cold from dashboard vents) with the auto climate control set to coldest temp, i should be checking that hose #3 is cooler then hose #1 ? sorry if my question sounds dumb
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  #24  
Old 05-11-2013, 11:10 AM
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ahull ahull is online now
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Correct
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2003 330i TiAg Sport Pkg
DIY MODS: AA Stage I supercharger, Meyle HD FCAs w Powerflex CABs, Bilstein shocks, Meyle HD Rtabs, Angel Eyes, Clear Corners/Markers w/ LEDs, LED tails, ZHP rims, Akebono pads, AUX input
DIY E46 Merit Badges: Sunroof resurrection, CCV, OFHG, VCG w/ VANOS seals, DISA, Cooling Refresh I, steering giubo, window regs, Magnetic Infandibulator (see wiki)
DIY On deck: Rear Diff bushing. UUC SSK, clutch job eventually, Wavetrac LSD
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  #25  
Old 05-11-2013, 11:24 AM
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ahull ahull is online now
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Mein Auto: ist schnell! (03 330i SC)
I never use the auto function to be honest but I just did on my car and I got NO air from wshield and foot w auto AC. Only dash vents. When I hit all three buttons for manual top, dash and foot vents, I got cold air from all 3. Auto turns off but remains on for fan speed until I change fan speed. 03 330. Getting heat when ac is on really makes me think heater valve
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2003 330i TiAg Sport Pkg
DIY MODS: AA Stage I supercharger, Meyle HD FCAs w Powerflex CABs, Bilstein shocks, Meyle HD Rtabs, Angel Eyes, Clear Corners/Markers w/ LEDs, LED tails, ZHP rims, Akebono pads, AUX input
DIY E46 Merit Badges: Sunroof resurrection, CCV, OFHG, VCG w/ VANOS seals, DISA, Cooling Refresh I, steering giubo, window regs, Magnetic Infandibulator (see wiki)
DIY On deck: Rear Diff bushing. UUC SSK, clutch job eventually, Wavetrac LSD
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