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///M3 Forum
The BMW E46 ///M3 is the M version E46 and puts out an amazing 333 HP and 262 lb-ft of torque at stock specs! There are an amazing amount of modifications for both the coupe and convertible models so read up and get started modifying your cars today!

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Old 05-30-2011, 07:29 PM   #1
MPowered72192
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Hot and Cold air blowing from vents, HELP!!

Hi guys,

I just bought a 2003 M3 with 93K miles on it from an individual. When I test drove the car everything seemed to be in working order, the next day, ALL HELL BROKE LOOSE. I live in south Mississippi where the weather is hot and humid so on the top of my list of things to fix is the possessed climate control system.

Here is my problem, when I first start my car in the AM (engine still cold) I get cabin temperature air from the floor vents and windshield vents while getting a/c chilled air from the dash vents. Once the car warms up to opp temp, the air from the floor vents and windshield vents becomes extremely hot, as if it was being heated. I have also on occasion had the blower motor become erratic where the speed cannot be adjusted and it will not turn off even with the climate control unit completely off AND the car off and key out. Final symptom I've observed, during some accelerations, the air blowing from the dash vents will become OAT warm and the air blowing from the floor and windshield vents will get even hotter.

After reading other post I self diagnosed the problem and decided it was ( or at least part of it was) a bad hot water control valve/ secondary water pump. I figured that when the stealership pulled a code regarding the secondary water pump, it was safe to assume it was bad. I ordered a new unit from Pelican Parts and installed it earlier, problem NOT solved.

Now I am at a loss. I dont want to keep throwing money at the car hoping I fix it eventually. I really hope someone else has had this problem and has resolved it and could point me in the right direction.

Thanks in advance!
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Old 05-30-2011, 09:45 PM   #2
wilsel
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One thing it took me a week to figure out myself is that there is a seperate temperature control for the dash vents. Next to the center vents (above the radio) there is a dial that can be adjusted. The top of the dial has red dots next to it, the bottom has blue dots. Turn it all the way down as far as it will go, and it should blow cold air if the ac is on.

For the blower motor issue, its probably the final stage resistor going out. Google it, it's a common problem, but easy to resolve.
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Old 05-31-2011, 12:14 AM   #3
MPowered72192
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Thanks man,
I already checked the blender, its all the way on blue dots and I am getting cold air from the dash, its the floor and windshield vents that are stuck on one temp...... HOT.

I had the same suspicion with the FSR, I'm leaning towards replacing that next, but I don't think that will fix the heat issue.
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Old 06-01-2011, 12:18 AM   #4
wilsel
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Can you tell if that valve is closing when the ac is on? There should not be any hot coolant going to the heater core unless the heat is on. If you've already replaced the valve, and its not closing, there could be a relay problem, or worse a faulty climate control unit. You might be able to leave it unplugged ( with it closed) to see if the problem still exists. I don't know if its closed by default, or if it is open, and closes when the car is started and your not asking for heat. I would assume it would be closed by default to help the car reach operating temperature quicker, but it is german engineered. Good luck!
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Old 06-15-2011, 04:54 PM   #5
MPowered72192
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So, issue resolved.

I just wanted to put some wisdom out there for anyone else who may experience this problem, CHECK YOUR FUSES! The hot water control valve has a separate fuse, #62 I believe.

So $300 and a lot of time and colorful words later, I replaced the <$1 fuse and now it works like a charm!

Thanks for all the suggestions anyway guys!
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Old 06-15-2011, 07:11 PM   #6
Andy_pha
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Thanks for posting the outcome. I hate that you had to spend a lot of money to find out you needed a cheap fix.
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Old 07-02-2013, 12:38 AM   #7
lingorama
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Quote:
Originally Posted by MPowered72192 View Post
So, issue resolved.

I just wanted to put some wisdom out there for anyone else who may experience this problem, CHECK YOUR FUSES! The hot water control valve has a separate fuse, #62 I believe.

So $300 and a lot of time and colorful words later, I replaced the <$1 fuse and now it works like a charm!

Thanks for all the suggestions anyway guys!
Was your fuse visibly blown when you replaced it? I'm having the same problem and fuse #62 seems fine but I'm replacing it just to be sure. Hopefully I don't need a new hot water valve...

edit: just saw that this thread is a couple years old, not from 6/18 of this year... sorry about that.

Last edited by lingorama; 07-02-2013 at 12:42 AM.
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Old 06-20-2017, 01:35 PM   #8
Kansas Corey
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Bringing this one back from the dead (a second time)!!

Short version - My A/C seemed ice cold sometimes and then other times mildly cool at best. Wasn't sure what the issue was and almost jumped the gun to try topping off the system. After I started reading some threads, though maybe it was the final stage resistor (FSR/FSU) or possibly the heater control valve. Things like relays and fuses also popped up. First thing I did was simple visual verification that AC compressor would engage when A/C was turned on.

The other night on my drive home from work, I started playing with the controls - really odd symptoms: all of these with air conditioning on MAX cold, blender wheel set to 3 blue dots, and fan maxed our as well --> Defrost vents only blow screaming hot air. Dash vents only blow slightly cool air from the right side and slightly warm air from the left side. Dash vents + floor vents blow cold air from dash and room temp air near feet. My best guess at this point is Heather Control Valve or the Flapper that directs air flow, but I hated to throw $100 - $200 at a part + spend the time changing it, only to find out the it didn't fix the problem.

After reading MPowered72192's post, I walked out to my car just now and voila - fuse number #62 (7.5 amp) was blown. Quick swap and for the minute, air conditioning is blowing ice cold again from all vents. I did check the other related A/C and heater fuses (23 - don't have this one on my car, 28, and 63) but everything seemed in good order. Now, I'm sure the next question is "why did the fuse blow" and unfortunately, I don't have an answer yet. My optimistic hope is that it was just really old , but that's more of a wish. My pessimistic side says that the heater control valve is somehow stuck and overloading the circuit which caused the fuse to blow in the first place.

I'm in Northern CA and we're having a heat wave with 100+ degree days right now which simply means that I can test the snot out of this thing to and from work the next few days. I'll update if anything changes.
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Old 06-20-2017, 04:54 PM   #9
Kansas Corey
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2:54 pm - not great news - haven't headed home yet, but took a short break and ran another search - found this thread. Basically it was his heater control valve causing Fuse # 62 to continually blow:
http://www.bimmerfest.com/forums/sho...d.php?t=618222

9:43 pm - 1st real update since this afternoon - drove home and A/C seemed to work well and blow cold. Problem is, when I got home and had a few minutes to play around, turns out I'm still blowing blast furnace hot air both at the windshield and near the feet.... Going to have to figure out how to diagnose the heater control valve, but looks like that might be the main suspect at this point in time. Good news is that Fuse #62 is still intact.

Last edited by Kansas Corey; 06-22-2017 at 03:59 PM.
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