bad heater control valve, how to be certain?

[VILeninDM]

Hi everyone, my wife's '03 330i just developed an interesting problem. No matter what temperature hvac is set at (including the calibration wheel in the middle of the dashboard), it only blows hot air.

I've searched this forum and other ones online and all things kinda point to heater control valve but there can also be other things. So today I opened up the car, found the HCV and tried to test to see if its bad. I disconnected the wires (there were 2, not 3 like some other people report) and voltage between those 2 was ~13V. Whether or not the wires were connected, car kept blowing hot air, so 0V is hot and 13V is hot kinda tells me that I'm right and HCV is bad. The only thing that I didn't get was when I tried to change temperature inside the car to all the way cold, voltage always stayed 13V, so that kinda makes me doubt myself.

Second question, if it is HCV, where is a good place to find a replacement part?

[ptarditi]

Is the outside temp in the cluster reading properly?

[VILeninDM]

yes, it is. And in case that matters, yesterday was around 65F.

[thejlevie]

BMW heater control valves are power applied to close. If power is present at the valve when the connector is in place and you have hot air, the valve is bad.

[mry82]

I admit I have not done the diagnostics yet, and I know I am reviving an ancient thread (feel free to post holy thread revival comments!), but in hopes the "BMW Tech Expert" above can offer some advice and guidance... or just some feedback to this question... I decided to post here in a relevant thread.

My AC will work every time from a cold start and sometimes it will work well for an hour long trip or more (haven't really taken it farther since this problem emerged), but sometimes within 15 minutes it will SUDDENLY start blowing very hot air, and continues to do so if the temp is turned all the way down and the condenser is turned off (after it starts blowing hot). Sometimes it happens when cruising at steady speed, sometimes in stop and go, with no pattern that I have noticed... I just had it in for second airbag recall and was told by dealer they just start with evac and recharge and go from there, but it is over $200 there, and from what I have read my issue does not sound like it would be related to the refrigerant level since it is a sudden onset of hot air from all vents (what I have read in the past is a bit rusty, but I was led toward maybe suspecting the heater valve sticking). If you turn the car off and back on the problem persists, unless the car sits for a while before re-cranking, in which case it works again, at least for a while, and seems to work well (which seems like it might not be the case if it was simply low on refrigerant). I have replaced the FSU with an updated unit because the fan speed used to have demons as well, but this problem did not resolve with that step...

So, anyone have ideas? I may get a quote, for EVAC and recharge, from an indy shop that works on them, but I thought I might just pick up a heater valve instead and start from there... What else could be the culprit? Blend door? Temp. sensor? Supernatural phenomenon? What do you guys think?

Thanks!

[ben4bama]

Prob the plunger in the HCV is stuck open

[bmwdirtracer]

The heater control valve is open when it is not receiving power. Therefore, an interruption in this circuit will cause hot coolant to be entered into the heater core, and thereby, the interior of the car.

The electric (auxiliary) fan is also crucial to proper cooling of the condenser. If the fan is not working properly, the pressures will rise, and the comprressor will shut off. (By the way, note that the COMPRESSOR can shut off, the CONDENSER cannot....it is a radiator).

The reason the dealership (or any good technician) will want to start by evacuating and refilling the system exactly is that this (1) establishes the baseline of proper fill, and (2) enables the tech to see both high-side and low-side pressures.....which is how you diagnose A/C systems.

It could well be that your expansion valve is bad, and the evaporator is freezing up; or the receiver/dryer is clogged / wet.

Is it the heater valve? Well, are the hoses into and out of the firewall HOT like the radiator hoses? (They shouldn't be.)

I am going to try and attach a factory 4 page article on diagnosing this HVAC system. It's officially much too large of a file, but maybe I can sneak it in, over several posts.

- - - Updated - - -

Okay, let's try page 2:

- - - Updated - - -

Hmm, it added on, rather than making a new post. I may not get away with page 3:

- - - Updated - - -

Wow....I've tried this before, and it didn't work....here goes the last page:

[mry82]

Thanks. I will read over that and see how much I might want to do myself, or just bail and go to the dealer or an indy shop. I appreciate the clarification about the compressor as well. Cheers!

[ptarditi]

First I don't remember e46s having an aux water pump, so I think you can rule that out. Second there is an easy check if the coolant hose leading into the valve is hot and the hose leading out is cold when you have the heat turned off and there is 12 volts at the valve, replace the valve. Had the same issue on my 330. Also is your air distribution set on cold? The valve is fairly easy to access, its on the driver's side (LHD) on the inner fender. The voltage supply is not resistance sensitive, so you can safely check it with a test light.

[mry82]

I will check these things out. Hard to do anything with a fresh baby, but certainly by next spring! :P

Thanks!

[bmwdirtracer]

I'm 20 minutes south of you, when I'm at work.

[mry82]

So... You still working on these things? I also have plans to replace bushings, mounts, etc... (with poly where possible) in the rear (figure on just dropping the rear subframe) as well... I´m happy to pay for good work, and this job is above my paygrade (and tools)! I plan on getting the GAS CCV system and DISA rebuild kit too, but I can manage those I think!

I actually live about an hour east of Asheville, but was considering checking out Joyners of some other Indy there (if you don´t work on them, any suggestions on where I would take it for AC and suspension work?).

Thanks Chris!

EDIT: Went delving back to look at what I had found here before, regarding mechanics, and I found this... Still accurate? If so I might be seeing you this fall... Thanks again!

Come and see me. I work at European Motor Werks, 308 Chadwick Ave. in Hendersonville. 694-3868

[bmwdirtracer]

Yep, that's where I work, every weekday.

[mry82]

I want to give a shout out to Chris (bmwdirtracer). Not only did he do a great job on my suspension work, etc... but he also fixed my HVAC problem (quoted below). Instead of me throwing random parts at the car, he blew the dust out of my old control unit (I guess the cabin temp sensor was getting a little choked up)... Yup, sometimes the answer is that simple. I was reluctant to post this before, fearing it might jinx me, but I have not had any recurrence of the problem (for 6 months, driven ~once/week), and the AC seems to be working like a champ. Thanks again Chris, hope to see you again soon for some more refurbishing of the ol' bimmer. Cheers!

I admit I have not done the diagnostics yet, and I know I am reviving an ancient thread (feel free to post holy thread revival comments!), but in hopes the "BMW Tech Expert" above can offer some advice and guidance... or just some feedback to this question... I decided to post here in a relevant thread.

My AC will work every time from a cold start and sometimes it will work well for an hour long trip or more (haven't really taken it farther since this problem emerged), but sometimes within 15 minutes it will SUDDENLY start blowing very hot air, and continues to do so if the temp is turned all the way down and the condenser is turned off (after it starts blowing hot). Sometimes it happens when cruising at steady speed, sometimes in stop and go, with no pattern that I have noticed... I just had it in for second airbag recall and was told by dealer they just start with evac and recharge and go from there, but it is over $200 there, and from what I have read my issue does not sound like it would be related to the refrigerant level since it is a sudden onset of hot air from all vents (what I have read in the past is a bit rusty, but I was led toward maybe suspecting the heater valve sticking). If you turn the car off and back on the problem persists, unless the car sits for a while before re-cranking, in which case it works again, at least for a while, and seems to work well (which seems like it might not be the case if it was simply low on refrigerant). I have replaced the FSU with an updated unit because the fan speed used to have demons as well, but this problem did not resolve with that step...

So, anyone have ideas? I may get a quote, for EVAC and recharge, from an indy shop that works on them, but I thought I might just pick up a heater valve instead and start from there... What else could be the culprit? Blend door? Temp. sensor? Supernatural phenomenon? What do you guys think?

Thanks!

[bmwdirtracer]

Well HI Glenn !!!

I'm happy to hear that the system's still working well for you. With all the major work, I'd forgotten about this little item. I hope all is well for you and your family, and I'm always here for you if you need.

Chris

[salzamani]

Hi Chris,

I’m turning to you because a few months ago you did such a good job of helping Glenn’s wife’s 03 330i that had a strange problem with the air temperature inside the cabin.

So here is what I have, 2010 535i E60 N54 it’s got 130k miles. I’ve got maybe 3-4 things wrong that I’m not certain what may be the cause. I’ll start with just one for now. I’m suspecting Heater Control Valve. If the car has been driven and is nice and warm after which I park it for say 20 min or more(these Symptoms don’t show if parked for less usually)when I initially get back in the car and start it I get hot air from the vents as if I have the heater on for at least 2 miles after which it starts to go back to normal outside temperature. Now I realize the engine area is hot and It is normal to a certain extent to get slightly warmer air compared to a cold engine but this does not seem like the normal amount. Of course I can turn on the AC and override this issue and within 20-30 seconds my problem is alleviated but I don’t want to put the extra load on the engine by running the AC when its not really necessary. Now I do want to point out that the vents on the driver sides have these symptoms more severely. Another words the passenger side vents loses that excess heat faster then the driver side vents but pretty much after about 2-3 miles of driving everything is pretty much back to normal. Yet if I park the car again for a period of time like mention before the symptoms start all over again. I also have noticed that when I run the AC everything gets really nice and cold and sometimes a bit too cold so when I try to blend some warm air with it to make it more comfortable I have to turn the gauge an awful lot of warm air like 80 degrees with it to achieve a comfortable 68-70 degrees temperature as if the heater is being too lazy to mix. What do you think Chris do you think like Glenn I might have a temperature sensor inside the cabin that is dusty or do you suspect it might be my HCV that is getting stuck at certain temperature? Finally, just in case you’re wondering non of these symptoms exist if the car hasn’t been driven overnight and Is obviously cool and I hop in it at any time of the day and go for a short or a long drive. The problem appears only after I park a hot car and drive it again after it’s been parked for 20 min or more.... what do you think Chris?

[MarcoZandrini]

Chris, let me chime in.

The heater control valve is open unless the climate control module (IHKA) is sending it 12VDC. What’s happening is when you switch off the ignition the heater control valve goes wide open. Some hot coolant flows into the heater core. BMW did this do that the coolant can flow through the heater core even if the car is located in Miami. This prevents the heater core from rotting out due to old coolant. Now, you wrote that the heat remains for a couple of miles. That seems like too long. Is the dash vent temperature wheel set to 3 blue dots?

[bmwdirtracer]

On a 2010 car, my very first step would be to hook up a good scan tool, and see whether there are any codes in the IHKA.

[salzamani]

Hi Marco, thank you for chiming in. So what you’re telling me is that this is partly by BMW design except the part about how long it takes to get cooler outside temp(2miles) into the cabin. As far as the 3 blue dots in the dash vent temperature wheel, this is a 2010 535i and I believe what you discribed is on older model cars. I don’t have a wheel with 3 blue dots but I do have a temperature gauge and I always have it set to the coolest setting and of course this is with AC off. Aditiinally there is climate control setting in the idrive system and yes I have navigated to that setting and have set that to the blue region for the cooler setting. Also I don’t know if this can be related but the blower motor of my fan in the dash will make a buzzing sound only when the AC has been turned on long enough to get things nice and cold (usually 1 min). If I turn off the AC the noise doesn’t go away until the temperature in the dash starts to lose the cold air and temperatures return to normal. As if the noise is driven by the cold air making the blower motor bearing loud. My guess is that this blower motor noise issue is not related to the hot air problem I have but I just wanted you to be aware of it. Incidentally today when I got off of work at 5pm the outside temperature was unusually cool. it was about 63 degrees out and after driving about 40 min to get near my house I decided to pick up a quick meal and I must have left the car parked for about 20 min which is long enough for the problem to show up but I guess because of the cooler outside temperature the hot air problem was very mild, perhaps even normal. So outside temperature does play a role somehow.

[salzamani]

Hi Chris, thank you for your guidance. I don’t have a scan tool although I’ve been eyeing the ones at harbor freight for a year now. Would any of those do the job? Also about a year ago I got one of those cables that connect to the obd2 port and I have a couple software (INPA & another one) that communicate with the vehicle. Would I be able to scan the IHKA with that software for codes?

[bmwdirtracer]

Yes, INPA will do it. No, a Harbor Freight thing will not.

Are you really sure that it's your blower fan making the noise, and not the motor for a control flap? It could well be that you've got a door between, say, the evaporator and the heater, which is sticky, and it's taking a while for the motor to make it move. Do you hear noises from the dash after shutting the car off?

INPA will tell you whether the computer can see the problem.

[salzamani]

The buzzing noise only comes after the AC has been on long enough to lower the dash temperature. The noise goes away after a good 1 min after the AC has been turned off and the dash temperature returns to normal. I would think it’s a bearing that is sensitive to temperature. Others have reported a lengthy procedure to get into the dash and replace this motor and have had success in alleviating that noise. So my guess is that it’s the motor that is making that noise and it’s not related to my hot air problem. I can try connecting my laptop and running INPA to pull codes. I wish INPA was easier to use. I’m so lost in there. Are you familiar with using INPA Chris? If so I can give you remote access to connect to my car...

[bmwdirtracer]

Nope, not me.

I use ISTA (BMW's diag system), Autologic (a $35,000) diag system, and Launch (for quick reading and maintenance resets). I have never used INPA, and I'm a computer dumb-ass.

Yes, it looks like replacing the blower is a bit of a PITA. Factory directions here:
https://www.newtis.info/tisv2/a/en/e...ntrols/Pb95l8U

No, I don't think the blower is your problem. Does your A/C control panel have a visible sampling fan grille? If so, by all means, blow that out.

[mry82]

Good luck salzamani!

[salzamani]

Yes it does have the visible sampling fan grill. I took a really strong shop vac to it first and then took a air compressor to it as well. It hasn’t really fixed the issue, still get the hot air sometimes. I think the cooler conditions winter time here makes it not as hot right now but I can tell it’s still there.

Chris, I did pull the codes using INPA and sorry a bit off topic but It is a more important issue right now actually. I get a 30FF code. I did change the coil packs and did the walnut blasting of the intakes valves 1 year ago. Never replaced the spark plugs. I lose about 1 quart of oil every 2 months using liqui moly 5W40 and pretty much lost the same amount of oil before switching from the bmw 5W30 twin turbo oil. Here is my concern, if the car is nice and fully warmed up and I accelerate hard another words put a good load on the engine like take it to 5k RMP’s I get the yellow “reduced engine power warning light” when I look at my charge pipe at the very bottom of the car where it connects, if I disconnect that and look into it there is a pretty substantial amount of film of oil in the that pipe. Is that normal? do I need a Catch Can to stop this oil? From your experience does the N54 Benifits much from a Catch Can? Could this be what’s causing the reduced power engine light. I wanna point out that a year ago before the walnut blasting was done if I had got the reduced power light it was pretty different in that the car ran terrible until I restarted the engine at which point it would be running fine until I got the check engine light again. Like it was running on 5 cylinders or something. That is not the way this yellow reduce power check engine light is behaving, it seems to be running on all 6 cylinders but the light is on nevertheless until I restart the engine. What do you think is likely the culprit for my problem this time? Here is the complete code from INPA

BMW 30FF ladedruckregelung, ladedruck Zu Niedrig
4763 druck zu niedrig
16 testbedingungen erfüllt
32 fehler momentan nicht vorhanden, nicht OBD-entprellt

I had cleared all the codes 2 weeks ago so this is a fresh code...