Which fuse serves the heater control valve?

[ltbrett]

I have a 2003 525 with no voltage to the heater control valve. Which fuse and what other components are in this circuit? Thanks.

Brett

[edjack]

Buy a copy of the Bentley E39 service manual. The issue is no doubt more complicated than a fuse.

[JimLev]

The heater control valve gets its power directly from the HVAC panel.

[ltbrett]

Thanks for pointing me in the right direction, Jim. If I understand the logic, one wire is ground and the other two are pulsed +12VDC by the HVAC panel. Is this HVAC panel susceptible to broken solder joints? Can you point me to a wiring diagram or to the correct wires to check at the back of the HVAC panel? Thanks.

Brett

[ltbrett]

I took a multimeter to the valves and revised my question above. Any ideas? Common failure mode of the HVAC panel? Thanks.

Brett

[blackknight530i]

What is the problem with the heater control valve in the first place? Most often the coolant gets crudded up in them and stops the solenoids from either opening or closing. There are rebuild kits on Ebay to fix that issue.

[ltbrett]

The valve itself tests fine. The problem is that I'm not measuring any voltage on the control wires at the valve. I read a good ground, but nothing else. I'm using an analog meter to make sure I catch any pulses.

Brett

[JimLev]

The valves are normally open with no power applied to them. (Do you have 1 or 2 valves?)
Does the motor just below the valves run? If you put your hand on it you can tell if it's running.

[ltbrett]

2 valves. I'm testing on Max ac so I'd expect them to be energized. There's no doubt that they are open at all times. Good idea to check the aux water pump, but my 525 doesn't have one. A mechanic with appropriate BMW-specific test equipment checked the ihka controller for faults but found none. So I'm guessing I need to find an open circuit fault.

Brett

[blackknight530i]

2 valves. I'm testing on Max ac so I'd expect them to be energized. There's no doubt that they are open at all times. Good idea to check the aux water pump, but my 525 doesn't have one. A mechanic with appropriate BMW-specific test equipment checked the ihka controller for faults but found none. So I'm guessing I need to find an open circuit fault.

Brett

The 525 does have an aux water pump, it's on the fan shroud, not integrated into the heater control valve like the v8s.

Sent from my SM-G950U using Tapatalk

[ltbrett]

That little bugger is well camouflaged. I'll check it this weekend when I change my belts.

[JimLev]

Paul, thanks. Forgot that his is on the shroud.

[ltbrett]

So I was frustrated and put this problem aside for a while. I'm ready to re-attack it. My original question still stands. What is the control circuitry path for the heater control valves? Is this HVAC panel known for broken solder joints or other common failure modes that would explain a lack of voltage at the heater control valves? Which pins on the HVAC controller should be energized when the valve is commanded closed? I did check the aux water pump and it is not running. Any help would be appreciated.

Brett

[schatzy62]

You really need to get a Bentley Manual Set. There are 800+ pages in book #2 of electrical diagrams.

There are 18 pages dedicated the the heating/ac system.

http://m.ebay.com/itm/Bentley-Repair...%257Ciid%253A3

[ltbrett]

Am I to surmise from the deafening silence that HVAC control panel faults are not common? No known issues here?

[JimLev]

I'll see if I can dig up something for you today or tomorrow.

[JimLev]

The HVAC panel has 2 fuses, F9-15Amps and F20-5Amps.
Look for these wires on the HVAC connector, they go to the water valves.
Yel/Brn pin 5 on the HVAC connector goes to pin 2 on the water valve connector.
Yel/Vio pin 6 on the HVAC connector goes to pin 3 on the water valve connector.

[ltbrett]

Jim, youda man. Thanks!

[HoZy]

You never even said what your problem was. But if parameters are not met they won't be energized to begin with.

What is your car doing or not doing?

Cheers
Mat

edit: I would've assumed in the past few months you would've purchased a bmw scanner/pasoft? Or looked up the bmw wds for some circuit analysis?

http://www.bmw-planet.net/diagrams/release/us/index.htm

[ltbrett]

Thanks, Mat. That's exactly the kind of reference I was looking for. I found the site some time ago and promptly forgot about it. The original symptom was hot air from the upper and lower vents while the A/C was on max cold. I figured out there was no voltage to the heater control valves. This week, I managed to get INPA working and the software thinks it is commanding the valves open and closed, but nothing happens. Learning INPA sucks, BTW. I got sidetracked by an issue where the car stalls off idle. I think I have that one figured out (bad cam position sensor). I'm diving back in this weekend.

Brett

[ltbrett]

Progress? Well, at least some fault codes:
30 aux water pump short circuit against U-Batt
31 left water valve short circuit against U-Batt
32 right water valve short circuit against U-Batt

Time to test the module and trace some wires!

Brett

[bourkeco]

I'm having the same issue on my 540 and haven't had time to really get into it. Please keep us up to date on what you come up with... thanks

Scott

[ltbrett]

I tested the system and found no grounds, shorts, or stray voltages. I managed to catch a 350mv signal from the controller to the water valve. I'm thinking the controller has an internal fault. INPA can't command either the valves or the aux water pump because of the ground fault. I got the signal to the valves by setting cabin temperature high.

Scott--if your issue is hot air from the upper and lower vents, first suspect faulty water valves. If you've already trouble shot to the point of having no signal to the water valves, you might be looking for a new controller like me.

Brett

[bourkeco]

I tested the system and found no grounds, shorts, or stray voltages. I managed to catch a 350mv signal from the controller to the water valve. I'm thinking the controller has an internal fault. INPA can't command either the valves or the aux water pump because of the ground fault. I got the signal to the valves by setting cabin temperature high.

Scott--if your issue is hot air from the upper and lower vents, first suspect faulty water valves. If you've already trouble shot to the point of having no signal to the water valves, you might be looking for a new controller like me.

Brett

My HVAC panel was replaced a couple years ago I'm thinking its the valves....
Thanks for the input..

[ltbrett]

New controller received, installed, problem solved. Thanks Jim & Mat!