AC Hot AND cold!

[nrp22101]

Just had my AC converted and charged. It worked great for the first couple days but now only one side of the car blows cold and the other blows hot. Am I looking at a bad control unit?
Any help would be appreciated.

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[shogun]

sound like a sticking water valve for one side. From ignition key position 1 (radio can be switched on) the heater valves get 12 V.

As they get only impulses the usual method to test with a digital multimeter (DMM) is limited, as it always only shows the middle/average value.
Switch the thumbwheel on the IHKA control panel to 28 degree C (max), then the +V line should be interrupted/cut off to the heater valves. At minium 16 degree C. ground/mass is fully on the valves, so that the valves close completely to interrupt the water/coolant flow thru the valves. Best way to test is to use one of the old style test lights (cord test light) with the thin pin to pinch thru the isolation of the wires of the heater valve wiring. With this way of checking one can test if the problem are the heater valves or the control panel/module. At max. 28 degree C. the light should be fully/always off, at 16 degree C minimum temperature the light should be fully on. In between 16 and 28 degree adjustment the light should blink, but in different intervals depending on the adjustment. Best is to switch the blower fan to max also, as otherwise the heater valves are adjusted automatically by the system, and the blinking frequency is reduced. There are more simple ones with only a bulb inside, but I use this one, can even test the ignition cables http://www.atu.de/extern/gfx/artikel/FS1_/FS1133_L.jpg

Or the control unit http://www.bimmerboard.com/forums/posts/220273/

[ltbrett]

Or you can feel the outlet lines from the heater valves. Check the valve wiring harness too.

[nrp22101]

sound like a sticking water valve for one side. From ignition key position 1 (radio can be switched on) the heater valves get 12 V.

As they get only impulses the usual method to test with a digital multimeter (DMM) is limited, as it always only shows the middle/average value.
Switch the thumbwheel on the IHKA control panel to 28 degree C (max), then the +V line should be interrupted/cut off to the heater valves. At minium 16 degree C. ground/mass is fully on the valves, so that the valves close completely to interrupt the water/coolant flow thru the valves. Best way to test is to use one of the old style test lights (cord test light) with the thin pin to pinch thru the isolation of the wires of the heater valve wiring. With this way of checking one can test if the problem are the heater valves or the control panel/module. At max. 28 degree C. the light should be fully/always off, at 16 degree C minimum temperature the light should be fully on. In between 16 and 28 degree adjustment the light should blink, but in different intervals depending on the adjustment. Best is to switch the blower fan to max also, as otherwise the heater valves are adjusted automatically by the system, and the blinking frequency is reduced. There are more simple ones with only a bulb inside, but I use this one, can even test the ignition cables http://www.atu.de/extern/gfx/artikel/FS1_/FS1133_L.jpg

Or the control unit http://www.bimmerboard.com/forums/posts/220273/

Seriously Shogun, can I just ship you my 8??? I need a clone of you here...of course I would likely be broke if I had to address all the issues but at least it wouldn't be like throwing darts while blindfolded.
Thanks again.

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[shogun]

There are for sure better experts for that model here in the forum, for the E31 I can only comments on parts which are identical/similar on the E32, for example the heater valves are same on E32, E31 and E34, M70 engine is same and many other parts.

[Timm]

Here's how to change the valves:

https://www.meeknet.co.uk/e31/E31_He...eplacement.htm

And a good way to test is to have the drivers temperature wheel set to the lowest setting (past the detent) - this should close both heater valves no matter what the other settings are. If one of the heater hoses is still hot - there's your man!

[nrp22101]

Here's how to change the valves:

https://www.meeknet.co.uk/e31/E31_He...eplacement.htm

And a good way to test is to have the drivers temperature wheel set to the lowest setting (past the detent) - this should close both heater valves no matter what the other settings are. If one of the heater hoses is still hot - there's your man!

Way ahead of you on that one, already printed out your instructions. Just to be clear, no difference between the V8/V12 right?
About how long should this replacement take?


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[ltbrett]

no difference. replacement is dead simple. be gentle with the old plastic.

[nrp22101]

Good to know, thanks.

no difference. replacement is dead simple. be gentle with the old plastic.

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[nrp22101]

So, I installed a new heater valve, one of the easier jobs on this car, but that didn't solve the issue. I tested the new one (not OEM) before installing just to be sure and both sides opened and closed ok. Am I looking at a bad control panel? Could it be that I have a freon leak and not enough pressure?
Any thoughts?

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[ltbrett]

It's not possible to have a freon leak if one side is cold. What were the results of the test procedure Shogun posted?

Brett

[Timm]

Easiest test is to set the drivers temperature to the coldest setting - start the car and then check if either of the heater hoses to the matrix gets hot - neither should - let us know what happens!

[nrp22101]

Easiest test is to set the drivers temperature to the coldest setting - start the car and then check if either of the heater hoses to the matrix gets hot - neither should - let us know what happens!

Thanks guys, so both hoses get hot and now I'm getting hot air on both sides.
Given I don't have Shogun's light meter, I followed Frankie's DIY guide to troubleshoot (http://www.frankies-bmw.com/8series/...ter_valves.php) and all the numbers check out and to reiterate the heater valves do actuate when power is supplied.
Could it be the IHKA control module?


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[Timm]

The heater valves should CLOSE when activated - they open when power is removed. At the end of this article I explain how to use a meter to measure the voltages at the heater valves. When the drivers setting is set to the hottest we would expect no voltage across the heater valves - when the temperature setting is set to the coldest we would expect around 12V across both:

https://www.meeknet.co.uk/e31/E31_He...eplacement.htm

[nrp22101]

The heater valves should CLOSE when activated - they open when power is removed. At the end of this article I explain how to use a meter to measure the voltages at the heater valves. When the drivers setting is set to the hottest we would expect no voltage across the heater valves - when the temperature setting is set to the coldest we would expect around 12V across both:

https://www.meeknet.co.uk/e31/E31_He...eplacement.htm

Thanks Timm, this makes sense.
When I tested the unit, the flats did open and the voltages checked out, that's why I'm stumped.
I really think it may have to do with the charge. When I had the AC charged a couple months ago, all systems were go. Ac blowing ice cold. Then heat from one side-cold on the other and now, nothing.
Time to throw some parts at it. Wuffer is sending me a climate control unit and if that doesn't do it, I'll get the ac recharged.
Cant wait to get some cold air blowing again in time for winter!

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[ltbrett]

Try this first. Start the car, get everything to operating temperature. Set both sides of the climate control to auto, activate the a/c button, and make sure the fan is on. Keep the temp wheels at something comfortable. Feel the three lines coming in/out of the heater valves. Now set both sides to max hot. If you have a friend do it, you can listen for an audible click when the valves cycle. Do you feel a difference in the heater lines (check all three)? Now set both sides to max cold, making sure you feel the driver's side temp wheel click in its max cold setting. Did you hear a heater valve click or feel a difference? Did the a/c compressor kick on? How about after five minutes? When the valves are off, they are open and the lines running to/from will be too hot to keep a hand on. When they shut, they will slowly cool, but they will feel cooler than before. After five minutes, you should be able to keep a hand on them. If they cool down, rotate the temperature wheels warmer by a few degrees, such that the car should still be calling for a/c not heat. Is there a change in the hose temperature? There shouldn't be. Let us know the results.

Brett

[Sicily]

Good morning from Belgium everybody .

My AC is blowing left under warm air. I have a new Valve and Ihka and wheel have been refurbished. When you start the car the airco is icecold but when the car gets warm the left side is warming up. The valve is clicking.

Which steppermotor is moving to close the internal valve left under? I see them al moving but maybe something is stuck? I looked inside with al little camera but it is difficult to see what is the problem. Anybody some ideas? Thanks in advance

[Timm]

Here's the manual for the IHKA:

https://www.meeknet.co.uk/e31/IHKA.pdf