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Old 01-09-2011, 06:50 AM   #1
carruths
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Heater blows but only cold air - help a newbie!

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...
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Old 01-09-2011, 06:56 AM   #2
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Bleed the system more. 3 or 4 times. Pour in cold, with bleeder off and it will fill the block. Then turn car on, close cap and run the car with the bleeder slightly open (it has a small slit when its almost screwed closed to let air out) and let the engine warm up. Keep an eye on the temp gauge as you are outside the vehicle. Air will start to spurt out, close it time to time to build some pressure, open it a bit again and let the water pump circulate. Let the car cool and fill expansion tank if it is low. Most likely will be. You car is not overheating? Or you haven't driven it long distance yet?
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Old 01-09-2011, 06:58 AM   #3
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How did you bleed?

I'll give you 95% odds that if what you report is true, that it's a bleeding issue. Seems to give everyone an issue.

Read some of the thousands of diys on bleeding...bleed with engine off, heater on full heat and 3 red dots on dial...fan on low.

Pour slowly with bleeder open. Burp upper hose. Persist until you get heat...do not open bleeder or cap when the car is running unless you know what you're doing...and you don't yet, so don't risk a major system protecting your engine by bleeding while it's running as many say here.

Use advanced search, bleeding in 'title;' read until one of the veins in your forehead pops, then you'll be ready!

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Old 01-09-2011, 07:55 AM   #4
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I was sure hoping it was only a bleeding problem! I'll give that a shot this afternoon. I was concerned that if I still had a problem with the heater control valve that coolant would never circulate through the heater core and therefore could not bleed the system. I've had no problems with the engine overheating, etc.

BTW - How do you KNOW that the heater control valve is functioning? Should I hear the solenoid operate?

Thanks for your quick replies!
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Old 01-09-2011, 09:34 AM   #5
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@Carruths
Sounds like you got some stubborn air pockets stuck in your cooling system..
So, make sure you elevate the front of your vehicle on ramps (or jacks if that's all you've got) to insure a good Bleed.
And, you Have to be patient, it'll take a good 30 minutes or so to bleed the air out of the entire system using the standard Bleed method (non engine start).
Note: As you Bleed you can give the upper rad. hose a few firm squeezes to help excavate the air pockets.

Good luck.

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Old 01-09-2011, 10:23 AM   #6
jacobs323i
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i was told by a few people on here that if the heater is blowing but not hot it is usually the thermostat is stuck usually just need to replace that! abot 2 hr diy and a therm is like 80
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Old 01-09-2011, 10:39 AM   #7
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@jacobs...

OP stated he has already replaced his Thermostat, along with...

in his third sentence : ..."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."
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Old 01-09-2011, 11:34 AM   #8
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Inside the cabin, the two main air ducts above your radio are seperated by a switch with red and blue markings. For heat, make sure there are three red circles showing or else you will get cold air.
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Old 01-13-2011, 02:42 AM   #9
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Hi,
I am new in this Forum. I am from Denmark and have the exact same problem.
Do you have any good news?

BR
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Old 01-13-2011, 03:59 AM   #10
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UH OH! :O make sure your vents are set on hot first xD (the lil red dot, not the blue one LOL)
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Old 01-13-2011, 04:10 AM   #11
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No worries. It is not my first BMW ;-) But the first not to deliver heat..
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Old 01-17-2011, 02:13 AM   #12
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Problem solved.

Flushed the heater core and water valve.
Refilled the system with the bleeder screw of. poured colant mix in until it ran out of the bleeder screw without airbobles.
refitted cap and bleeder screw.
Started the car.
climate to 32deg C - Fan Low.
2500-3000rpm until the car was warm and the thermostat opened.

And there has been heat ever since :-)
One happy family.

Greatings from Denmark
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Old 01-17-2011, 02:54 AM   #13
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Originally Posted by Lune View Post
Problem solved.

Flushed the heater core and water valve.
Refilled the system with the bleeder screw of. poured colant mix in until it ran out of the bleeder screw without airbobles.
refitted cap and bleeder screw.
Started the car.
climate to 32deg C - Fan Low.
2500-3000rpm until the car was warm and the thermostat opened.

And there has been heat ever since :-)
One happy family.

Greatings from Denmark

Make sure you check the coolant one more time in the morning.
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Old 01-17-2011, 02:56 AM   #14
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Did that. Thanks
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Old 01-17-2011, 09:15 AM   #15
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Where is the heater core? and how do you flush it?
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Old 01-17-2011, 12:23 PM   #16
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demount hose B and C on the pic at the top and flush with a water hose.
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Old 01-17-2011, 10:01 PM   #17
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Ok where is the water valve? lol
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Old 01-17-2011, 10:18 PM   #18
carruths
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Well it's been a bit before I could get back on this problem. I just saw the post from Lune and I will try that next. Since I last posted I've tried bleeding cold, bleeding hot, bleeding elevated and every other kind of bleed. I (sort of) gave up and took the car to someone to flush and refill the coolant and no change. I went through the entire bleeding process again taking plenty of time. At no time did I EVER get hot air in the car and YES, there are 3 dots visible on the center vent. During this process the check engine light came on. I used an OBD tester and had code P0128 which most of you know means low coolant temp. I had trouble believing this for two reasons - I replaced the thermostat and housing AND it seemed plenty hot! I hooked up the OBD tool and simultaneously used the on-board display diagnostics and the temperatures were identical (although one in deg C and the other in deg F.) I ran the car for about 30 minutes around town, etc. and the temperature varied between 193 and 199 deg F which seems right on the money. I reset the code and it has not come back on. However, no dang cabin heat. Beyond that, Hose A STILL remains somewhat cool to the touch anywhere near or behind the heater control valve location - that doesn't seem right. Next I'll try Lune's suggestion. Do any of you have a picture, diagram, etc. that shows the specific routing of the hoses A, B and C from the topmost picture? Bentley doesn't show it and the others I've seen don't look like my car which is a 2001 BMW 325CI automatic. Thanks for all the suggestions thus far - we WILL prevail over this heater!!!
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Old 01-17-2011, 11:48 PM   #19
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Ok where is the water valve? lol
The one at the end of the hoses B and C
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Old 01-18-2011, 07:44 AM   #20
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ohhh ok so the water valve connects to the heater core?
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