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      04-30-2021, 09:41 AM   #1
capt.pancakes
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A/C misbehaving!

Alright - I feel like I've been posting a lot, but for what it's worth, every question I've posted you guys have helped me with - so don't blame me! haha

So as I mentioned in a previous post the A/C is not working. When I purchased the car it had a second compressor in the trunk and the previous owner genuinely just shrugged his shoulders when I asked what was wrong with the A/C. He said that the new compressor should fix it all up, but he just never got around to it (Now we've all heard this line a dozen times).

I took it to the only shop in my area that had any real confidence with working on a BMW and they kept it for a day and a half investigating and here's what they came back with:
The doors in the HVAC plenum are broken.

Now my elementary understanding of HVAC (read: wikipedia/googling) tells me that these plenum doors are what control the flow of the air - that the air always flows over the A/C evaporator, but this door is what controls how much of it mixes with air from the heater core. It sounds like my door is broken/stuck and all of the air is mixing with the heater core because the air is nice and warm.

They went on to tell me that the A/C compressor is working, the clutch is engaging and that it is chilling the air, and that the system is charged (they topped off with 1 unit of Freon but the mechanic said that they tested with their dye and found no leaks).

They told me that they could fix the plenum issue for $3500 and honestly that seems excessive, right? Does anyone here have any experience with the HVAC system or at least have a direction they can point me? I will continue my googling, but wanted to see what y'all thought while I was at it!
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      04-30-2021, 10:28 AM   #2
capt.pancakes
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Hmm - so yeah I'm replying to myself - just providing an update.

I have found some articles discussing the 'blend door' and how the blend actuator can fail and is more likely the problem (based on random people on the internet with unrelated cars) ... so I guess I can order a replacement blend door actuator and try replacing that? Looks to only be about $80 on eBay, much cheaper than $3500!
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      04-30-2021, 11:02 AM   #3
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Yes, try that first. I think you could buy an entire new system from bmw for under 3500 - it is easy to replace on your own. 3500 is highway robbery.
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      04-30-2021, 11:03 AM   #4
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Get a copy of the TIS which will tell you how to access and fix.

You are going to need to tear into the dashboard if I remember correctly and that is why the high quote….
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      05-12-2021, 09:07 AM   #5
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So a small update on this interesting situation.
The HVAC actuator drive that I had found behind the glove box looks brand new (had me very disappointed when I found that, because that means someone tried to do this fix already). I removed it, and while holding the drive turned the A/C on and off, and I see the drive is spinning and appears to be functioning correctly. So disappointed I reinstalled it, then decided I’d go ahead and test it again just to see if I could figure anything else out… but low and behold now there’s an obvious “whirring” sound from down there when I turn on the A/C and adjust the direction of the air (defrost, feet, or face).

Now the A/C still isn’t working, but I can now change the direction of the air (when I turn the dial to feet, the air blows to my feet, when I turn the dial to face, the air blows in my face). So that tells me that this actuator wasn’t installed correctly when it was replaced. So… a small victory, one small aspect of the A/C is working now - but I still can’t control the temperature!

I’m using a Russian hosted TIS that is being translated to English using Google Translate, and that is a big reason why I’m sorta not sure because it called the part I found “Air Conditioning Air Blend Actuator” but cross-referencing the part number I found on the actual unit it looks like in actual English it’s the “Actuator drive for central kinematics” which sounds like a fancy name for “controls the direction of the air flow”...

So that's an update haha.
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      05-12-2021, 12:06 PM   #6
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Realoem shows 3 different actuators for the A/C.

https://www.realoem.com/bmw/enUS/sho...diagId=64_1282

Unless you have automatic air conditioning, in which case there are 5!

https://www.realoem.com/bmw/enUS/sho...diagId=64_1281
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      05-12-2021, 01:54 PM   #7
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Quote:
Originally Posted by wdb View Post
Realoem shows 3 different actuators for the A/C.

https://www.realoem.com/bmw/enUS/sho...diagId=64_1282

Unless you have automatic air conditioning, in which case there are 5!

https://www.realoem.com/bmw/enUS/sho...diagId=64_1281

Thank goodness I don't have the automatic air! So - what's weird is, this looks reversed to me... now what's even weirder is the part that I did find under my dash is part#:
69026959 (113930-0270-A)... which pulls up https://www.realoem.com/bmw/enUS/partxref?q=64116902695 ... which is for a fresh air actuator flap for 2 different BMW models that aren't the z4! I guess the part must obviously be interchangeable, but definitely doesn't help me get my bearings at all! haha...

In any case - the image from RealOEM looks reversed, almost makes me wonder if that's the EU config for LHT?
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      05-12-2021, 11:27 PM   #8
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There are def 3 actuators. I remeber counting them before i bashed the crap out of my HVAC. TRy to find someone whos turned thier car into a track/race car as most likely they would have removed the HVAC.

Edit, picture is NOT reversed, thats how mine was. the actuators are on the right hand side. Possibly if you have a left hand drive car?
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      05-13-2021, 08:59 AM   #9
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I currently have the same problem with my 2003, and gave up on trying to access all of the actuators. I couldn't find a way to do it without pulling the whole dash, and the shop I used to do the troubleshooting said the same thing and quoted $2500ish.

Since I don't drive it in the winter, I bypassed the heater core so there's no hot coolant going through it. I now have A/C that works, but not heat.

If I decide in the future I want heat, I may go with an electronic bypass valve like this that hotrodders and older cars use: Electronic Heater Bypass Valve
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      05-13-2021, 09:39 AM   #10
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Quote:
Originally Posted by nadaclue View Post
I currently have the same problem with my 2003, and gave up on trying to access all of the actuators. I couldn't find a way to do it without pulling the whole dash, and the shop I used to do the troubleshooting said the same thing and quoted $2500ish.

Since I don't drive it in the winter, I bypassed the heater core so there's no hot coolant going through it. I now have A/C that works, but not heat.

If I decide in the future I want heat, I may go with an electronic bypass valve like this that hotrodders and older cars use: Electronic Heater Bypass Valve
Being that I have absolutely no idea that this is even possible (and I haven't done any googling yet haha) do you have any documentation/DIY/instructions on this? For any sort of vehicle? I understand that HVAC is mostly the same on most vehicles haha.
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      05-17-2021, 11:53 AM   #11
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Well following the advice/comment from nadaclue, I bypassed the heater core entirely for the time being and now the A/C is ice cold!

Obviously not really a solution, but it's an effective workaround, and it is just a toy car that stays in the garage except on sunny days - so for what it's worth, I'm gonna call this 'fixed' for the time being haha.
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      05-18-2021, 11:57 AM   #12
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I found that to be the easiest fix for now. Might not bode well for potential resale at some point, but at least it can be driven in the heat of summer.


Quote:
Originally Posted by capt.pancakes View Post
Well following the advice/comment from nadaclue, I bypassed the heater core entirely for the time being and now the A/C is ice cold!

Obviously not really a solution, but it's an effective workaround, and it is just a toy car that stays in the garage except on sunny days - so for what it's worth, I'm gonna call this 'fixed' for the time being haha.
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      05-19-2021, 10:15 AM   #13
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Well like you said - maybe down the road I can install an electronic bypass valve to enable/disable the heat.
But in the mean time, I don't care about resale value haha - I mean I only played a few grand for the car, I doubt it can bottom out too much more!
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      07-07-2021, 08:18 AM   #14
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Similar problem

My A/C decided not to work recently.
I took the Z to the garage they checked the pressure and it was like 120lbs so he said there is no leak but that is high. He hooked it up to there A/C machine and it pumped the system down then restored the right pressure and mix back in. No difference.
System set - No leaks, compressor is kicking in and out with the switches.
I'm wondering if it could be the compressor?
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      07-07-2021, 11:31 AM   #15
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Quote:
Originally Posted by acvr4 View Post
My A/C decided not to work recently.
I took the Z to the garage they checked the pressure and it was like 120lbs so he said there is no leak but that is high. He hooked it up to there A/C machine and it pumped the system down then restored the right pressure and mix back in. No difference.
System set - No leaks, compressor is kicking in and out with the switches.
I'm wondering if it could be the compressor?
A set of A/C gauges has 2 separate gauges (1 high/1 low). I'm assuming the low side was too high @120lbs. With a set of gauges, a competent A/C tech should have been able to diagnose if the compressor with the related components where working properly and if not what part of the system is faulty. They just removed the freon, added it back and charged you without diagnosing what the problem is?

Last edited by pungo; 07-07-2021 at 03:08 PM..
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      07-08-2021, 01:47 PM   #16
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Tested

Quote:
Originally Posted by pungo View Post
Quote:
Originally Posted by acvr4 View Post
My A/C decided not to work recently.
I took the Z to the garage they checked the pressure and it was like 120lbs so he said there is no leak but that is high. He hooked it up to there A/C machine and it pumped the system down then restored the right pressure and mix back in. No difference.
System set - No leaks, compressor is kicking in and out with the switches.
I'm wondering if it could be the compressor?
A set of A/C gauges has 2 separate gauges (1 high/1 low). I'm assuming the low side was too high @120lbs. With a set of gauges, a competent A/C tech should have been able to diagnose if the compressor with the related components where working properly and if not what part of the system is faulty. They just removed the freon, added it back and charged you without diagnosing what the problem is?
It was a A/C computerized system unit - you hook up the hoses and it tests and will drain the system refill it .
They did that and it still doesn't work. They didn't charge me he said to give it a day - been several and no difference.
I'll schedule an appointment with them but I figured if done had a similar experience they could enlighten me 😉
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      07-08-2021, 04:12 PM   #17
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Quote:
Originally Posted by acvr4 View Post
It was a A/C computerized system unit - you hook up the hoses and it tests and will drain the system refill it .
They did that and it still doesn't work. They didn't charge me he said to give it a day - been several and no difference.
I'll schedule an appointment with them but I figured if done had a similar experience they could enlighten me 😉
I understand it was a machine they connected it to, that's the only legal way to evacuate the system. I doubt the person knows a/c systems since they told you to give it a day, that's not how it works. If it wasn't blowing cold and the low side shows 120psi, there's a problem and the tech should have been able to diagnose or at least provide you with the possible causes (i.e. bad expansion valve). I'm surprise they didn't charge you, maybe they were looking at it like you were a guinea pig and they were learning with your car
Good luck sorting it out.
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      07-21-2021, 08:37 AM   #18
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Quote:
Originally Posted by pungo View Post
Quote:
Originally Posted by acvr4 View Post
It was a A/C computerized system unit - you hook up the hoses and it tests and will drain the system refill it .
They did that and it still doesn't work. They didn't charge me he said to give it a day - been several and no difference.
I'll schedule an appointment with them but I figured if done had a similar experience they could enlighten me 😉
I understand it was a machine they connected it to, that's the only legal way to evacuate the system. I doubt the person knows a/c systems since they told you to give it a day, that's not how it works. If it wasn't blowing cold and the low side shows 120psi, there's a problem and the tech should have been able to diagnose or at least provide you with the possible causes (i.e. bad expansion valve). I'm surprise they didn't charge you, maybe they were looking at it like you were a guinea pig and they were learning with your car
Good luck sorting it out.
Quote:
Originally Posted by pungo View Post
I'm surprise they didn't charge you, maybe they were looking at it like you were a guinea pig and they were learning with your car
Good luck sorting it out.
I know the owner (BMW guy) and his son did work on my Z4 before. I was very happy with their knowledge on figuring out the problem.
The son tested it and then had the system re-filled and pressurized .
The system if filled and not leaking, compressor is engaging when the a/c is turned on and all air directions (vent settings) are working .

I'm thinking that there is a problem in the a/c pump🤔
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      07-21-2021, 11:52 AM   #19
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Quote:
Originally Posted by acvr4 View Post
I know the owner (BMW guy) and his son did work on my Z4 before. I was very happy with their knowledge on figuring out the problem.
The son tested it and then had the system re-filled and pressurized .
The system if filled and not leaking, compressor is engaging when the a/c is turned on and all air directions (vent settings) are working .

I'm thinking that there is a problem in the a/c pump🤔
I'm sorry, but if they did not tell you the possible reason(s) why the a/c is not blowing cold air, they don't know how to diagnose, therefore, don't know what they're doing

Never heard of an a/c pump, what is it?
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      08-14-2021, 06:21 AM   #20
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Quote:
Originally Posted by pungo View Post
Quote:
Originally Posted by acvr4 View Post
I know the owner (BMW guy) and his son did work on my Z4 before. I was very happy with their knowledge on figuring out the problem.
The son tested it and then had the system re-filled and pressurized .
The system if filled and not leaking, compressor is engaging when the a/c is turned on and all air directions (vent settings) are working .

I'm thinking that there is a problem in the a/c pump🤔
I'm sorry, but if they did not tell you the possible reason(s) why the a/c is not blowing cold air, they don't know how to diagnose, therefore, don't know what they're doing

Never heard of an a/c pump, what is it?
Ok - you know I meant the A/C compressor 🙄
I had a thread message suggesting the A/C relay so I'll check that.
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      08-14-2021, 08:04 AM   #21
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Quote:
Originally Posted by acvr4 View Post
Ok - you know I meant the A/C compressor 🙄
I had a thread message suggesting the A/C relay so I'll check that.
If the compressor is engaging, there's nothing wrong with the A/C relay. You need to take it to someone who knows how to properly diagnose a/c systems, it's not a guessing game
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