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General E46 Forum
This is the place to get answers, opinions and everything you need related to your E46 (sedan, coupe, convertible and wagon) BMW!

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Old 01-18-2011, 07:56 AM   #21
Lune
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yep
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Old 01-18-2011, 08:11 AM   #22
carruths
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I'm following the discussion between Lune and juanmurillo. To help juanmurillo and me, can you tell me how the coolant flows through the heater core? In my top picture, there's a hose from the coolant tank (hose A) that runs to the back of the engine bay. There are also hoses B and C. From the arrow on the heater control valve, I assume that heated coolant flows into the valve from hose B and then back to the heater core through hose C. How does the actual coolant circulate back to the engine? Three hoses does not equal a complete path so I'm missing something. Also, when you flushed the core, did you remove both hoses B and C and then pressurize C or did you reverse flush and pressurize B and get flow back out of C? Sorry for the long question - without a diagram it's hard to understand.
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Old 01-18-2011, 08:15 AM   #23
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This should describe the flow.


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Old 01-18-2011, 08:29 AM   #24
carruths
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Awesome - so, heated coolant flows through hose 1, into the heater control valve, through hose 3 and into the core. It then returns through hose 5 and drains back into the engine. Is that correct?

Does the thermostat need to open in order for coolant to flow from hose 5 back through hose 1?

If I remove hoses 1 and 3, will the pressurized water I'm flushing with be "trapped" due to the thermostat or will it flow anyway?

Dang - I ask a lot of questions! One more...

In this diagram, is it true that hose 4 going to the coolant tank is for some other purpose unrelated to the function of the heater?
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Old 01-18-2011, 10:59 AM   #25
juanmurillo
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Ok so today I get to it and come to find that only one hose from my heater control valve was plugged in and the other one was just hanging there. Isn't water suppose to be running through these hoses all the time?
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OH...and you didn't knock on wood.....you're in for a world of sh*t. Better be prepared to bust out the mastercard and bend over in front of a mechanic.

Last edited by juanmurillo; 01-18-2011 at 11:01 AM.
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Old 01-18-2011, 11:26 AM   #26
juanmurillo
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Ok while taking a look at this in my car it seems like my hose a is connected to my hose b with a metal tube. There was another hose just hangin there. I'm confused lol
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Old 01-18-2011, 11:31 AM   #27
carruths
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Sounds like someone bypassed your heater control valve. I guess that's cheaper than buying one! They're not that expensive and they're easy to replace - assuming you ever get the system correctly bled afterwards!!
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Old 01-18-2011, 11:34 AM   #28
juanmurillo
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What will happen if I connect it how it should be if the heater
Valve is faulty?
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OH...and you didn't knock on wood.....you're in for a world of sh*t. Better be prepared to bust out the mastercard and bend over in front of a mechanic.
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Old 01-18-2011, 11:42 AM   #29
carruths
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If you are getting heat now because it's bypassed, then I would assume you'd not get heat. But heck - what do I know? I can't get it working after I replaced the valve either!
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Old 01-18-2011, 11:55 AM   #30
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Haha man stupid heater haha. I'm not getting heat at all. I'm going to have to do it right and get rid of the bypass.
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Old 01-18-2011, 10:35 PM   #31
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I spent some more time this evening based on earlier discussions. My frustration is rising because we don't seem to be getting anywhere. I read through many of the posts related to flushing the heater core and most all of it was worthless both in terms of clarity and process. Having only the diagram to go on provided by Lune, I did the following:
1. With engine lukewarm, key on, engine off, heater at 91F, low fan, removed the coolant tank cap and opened the bleeder screw
2. Removed the air box to make room.
3. Jacked the car up and removed the pan from the bottom of the car
4. Drained coolant from the bottom of the radiator
5. Removed hoses 3 and 1 from the heater control valve but kept the hoses elevated to minimize coolant loss
6. I applied pressure with another hose to hose 3 (the upper hose as mounted)
7. Absolutely no water flow could be made - it was as if it was dead-headed against the thermostat which it may well have been.
8. I applied pressure with another hose to hose 1 (the lower hose as mounted)
9. After a short bit of water flow, the water backed up in the coolant tank and began to overflow
10. Replaced the heater control valve
11. Drained the water back out of the radiator
12. Refilled and bled the coolant as it went
13. Replaced the air box
14. Replaced the coolant cap, tightened the bleed screw and heated up the engine
15. Drove the car while watching the coolant temp using an OBD scanner - hovered between 193 and 198 driving, peaked at 202 after stopping
16. With engine coolant below 180F, opened the coolant tank cap and bleeder and topped off
17. Tested heater, still no heat!!!!

Ideas???

Last edited by carruths; 01-18-2011 at 10:36 PM. Reason: extra characters at bottom of post
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Old 01-19-2011, 08:21 AM   #32
juanmurillo
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Ok so FINALLYY!! i have warm air yaaayy!! my problem was that the previous owners by passed the valve and ran it direct in the enging. I connected the hoses the way it should go and nothing. then i thought maybe i connected them wrong on the valve so i disconnected them and swwitched them and got cold air then i looked at the little thingy on the middle ac vents and it was on cold so i moved the dial down to hot and boom waarrmm aaiirr baby!!
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OH...and you didn't knock on wood.....you're in for a world of sh*t. Better be prepared to bust out the mastercard and bend over in front of a mechanic.
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Old 01-19-2011, 12:52 PM   #33
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lol man all that work for something that takes 1 seconds to do
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Old 02-05-2011, 04:46 PM   #34
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How about a link to "Bleeding Procedure" Please.
Thanks In Advance
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Old 02-05-2011, 05:31 PM   #35
iansanderson
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To the OP: Did you use Genuine BMW OEM parts or aftermarket, autozone, ebay, internet? I can't tell looking at the pictures.
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Cheat Sheet:

GT1/ISIS/MoDiC = Factory authorized diagnostic system used by BMW dealerships across the world.

NCS Expert = BMW Factory R&D programming tool available on the internet (not intended for the public and not available to the dealership network)

OEM = Genuine BMW part only available from a franchised BMW dealership.

DME = Engine Management Computer
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Old 03-31-2011, 08:42 AM   #36
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Hey all so i have the same problem, cold air at all times sometimes in recirculating air and fan speed at 2 notches and temp at 91..i get a slight warm breeze from the center vent..but once i crank up the speed... the air gets colder... I have tried to bleed the system and i am getting no where.. i guess my next thing to do is replace the water valve, do i need to replace the temp sensor as well? the Tstat is no more than 5months old as well as the whole coolant. When i replace that water valve....if that doesnt fix the problem...what are other commonly known things to check/raplace? (AC works cold) thank you!
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Old 03-31-2011, 09:07 AM   #37
shanneba
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What does your OBD outside air temp display? That value is used by the IHKA for heating and A/C. If it reads 122F, the IHKA would believe that no additional hot coolant from the engine would be needed to warm up the inside of the car, it would just pull in 122F outside air.

If the Heat exchanger temp sensor fails, the substitute value used by the IHKA is 131F, the IHKA would believe the heater core is at 131F and would not need any additional heated water from the cooling system to heat the interior
At 77F the heater core sensor should measure 9K ohms +- 2%.
It is located behind the IHKA control panel. The Bentley manual shows a white colored sensor with a two wire connector.
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Old 04-01-2011, 04:44 PM   #38
Bert336
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Quote:
Originally Posted by shanneba View Post
What does your OBD outside air temp display? That value is used by the IHKA for heating and A/C. If it reads 122F, the IHKA would believe that no additional hot coolant from the engine would be needed to warm up the inside of the car, it would just pull in 122F outside air.

If the Heat exchanger temp sensor fails, the substitute value used by the IHKA is 131F, the IHKA would believe the heater core is at 131F and would not need any additional heated water from the cooling system to heat the interior
At 77F the heater core sensor should measure 9K ohms +- 2%.
It is located behind the IHKA control panel. The Bentley manual shows a white colored sensor with a two wire connector.
hey there, thanks for your reply...eventhough im lost with all that knowledge you just threw at me lol...
Here is the reading i got earlier today on my way home (1hr hwy drive)

Temperature outside: 51 degrees
Coolant/Engine Temp : steady at 95 degrees 90% of the time bout would fluctuate between 93-96 degrees
RPM / Speed : 2500rpm @ 70mph

no warm air at all. I came home and my water valve had came in the mail. replaced it bled thecar again let it warm up at idle.. took it for a drive and it gave me a breath of warm air for a bit as i was driving with near half way of Fan speed...i turned it up to almost max speed and the air just got cold. I posted on another thread about this as well...but if you guys can help me out i will be very thankful
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Old 04-23-2011, 03:12 PM   #39
bmwAlex
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Quote:
Originally Posted by carruths View Post
I've been looking to E46Fanatics for information since I bought my 2001 325CI. The heater is giving me a fit. I took the car to a shop who wouldn't touch it and ended up at the dealer where they diagnosed a bad thermostat and heater control valve. I replaced all the parts myself including a new upper radiator hose, thermostat/housing, coolant tank, AT thermostat (it broke when removing the tank, of course) and a heater control valve. I followed the information from this forum and everything when back together perfectly, no leaks, etc. However, still no heat! I took a picture of the hoses and valve. When the car is warm/hot, the hose from the tank to the back of the engine bay (marked A) is only hot for about 8 inches leading from the coolant tank, then it seems very much cooler. The hoses leading to and from the heater control valve remain cool (Hoses B and C). I checked all the heater/AC related fuses and all are OK. I cannot measure a voltage across either pin of the connector on the heater control valve but the Bentley diagram doesn't give sufficient information for me to know what to expect. I've followed the recommendations to bleed the coolant and I've no further ideas. Any help out there?


Newbie from Texas...
I realize this OP is quite a while back...I seem to be experiencing the same issue you have. I am thinking it is a plugged heater core because I have not touched anything in the cooling system that would entail bleeding. I had heat all last year, going into the fall...the car was parked for the winter, starting it every 2 weeks and when I pulled it out for the spring it now has NO heat!

From your picture I pulled hoses B and C off and from hose C (the one leading to the heater core) small sediment washed out with it. I want to know which hose I need to hook up to flush the heater core. I want the fluid to come out of C and B must be coming from the engine to supply heat but where is the other hose...is it the line that feeds to the reservoir? All three hoses A, B, & C are heading that direction towards the firewall.

Any thoughts? and have you resolved this issue?
-Alex

(Sooner rather than later would be great...car in pieces, haha)
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Old 06-24-2011, 08:30 PM   #40
Scotty_89
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Bump.

I still don't get this.

My heater was working fine for 6 months after the first bleeding - then the heater stops blowing hot. How could it be a bleeding issue? I did nothing with the coolant system in the 6 months that would cause bleeding issues.
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