czachari

I had both "Auto" on and "A/C off" button on. Made a sharp left turn and the "Auto" button light went off and the "A/C off" button was blinking. Have you guys seen this before?

mtnman82

Hate to say it ... but I had a problem with the 'auto' lite & function turning off all by itself in my '03 c230k while still under factory warranty. They wound up replacing the whole module and everything has been fine since.

By module, I mean the part you see/touch with the knobs/buttons on it. The one they replaced it with looks slightly different than the original (the A/C off button also has 'rest' on it, and I believe a light next to the word 'rest', but I've never seen the light come on, even when I'm using the A/C and it cycles off).

czachari

And it only did this once. Today it was fine. So, maybe it was a fluke. I actually saw the little A/C module with the digital display on it. It's only around $200 or less. At one point I thought about getting it just for the looks. I guess the new owner may have to replace this at some point if it becomes a real issue.

vadim

Have had this happen many times. These switches are mechanical and can often be affected by jolts from road imperfections or hard acceleration. Especially if you set them to "Auto" - it takes close to nothing to move them "off" that position. Just put them back on manually and go on! (Or move on )

czachari

ttyl

vadim

C230 Sport Coup

Hey Vadim
yer still commiserating with us lowly C class owners?
Cool

vadim

It's hard to get over. Plus I am still connected in a way: agreed to store the new owner's (friend of mine) floor jack and winter wheels and swap them twice a year

mbz4810

I had this problem for a while now; since under warranty to out of warranty... I complained under warranty; dlr did not do anything because they cannot duplicate the problem...

Now out of Warr. and I just turn on manually ;-)

patrick_y

Vadim is trying to convert us to E92 3-series people. For those of you thinking of changing to a new car, the new BMW 3-series coupe is very impressive and worthy of your consideration. Believe it or not, I would actually acquire the new BMW E92 over the W204!

Stick around Vadim!

SickSpeedMonte

Bringing this back from the dead...

I had this problem intermittantly, and now it is to the point where it happens several times in one hour long commute. I was searching for an HVAC re-sync procedure, and was unable to find it on the forum or in the manual.

It's an '07 C230 sport sedan with the knobs to control the temperature (I believe that I read that there's a digital option).

Luckily, I'm still under warranty, so if a re-sync doesn't exist, or doesn't fix it, I can get it replaced.

jcnash

Your battery is low. The computer is switching off all major power consumers to save power.

Switch off environmental control, radio, seat/steering heater, unplug everything from the cig lighter socket (all major power consumers) and drive around at a constant speed for a while. this will recharge your batteries.

if that doesn't work you might have to change your battery because its not holding charge too well.

SickSpeedMonte

If that's the case, its a bad alternator. This happens while driving 70 down the highway. Wouldn't a warnging pop up in the display? This car tells me everything else that could be wrong, I'd imagine a car with no immediately visible voltage meter would have to notify you through the display of a problem.

I'll check it out in dyno mode to see what the voltage reads, but I definately need to get it into the shop so that they can get it fixed and I can make sure of it before another 7500 miles go by and I lose my factory warranty.

mleskovar

This use to happen to me all the time. Only the driver's side would shut down, and at varying times between instances. I had everything (lower dashes and center stack) out looking for a random clicking noise several times and finally ended up disabling the right defrost stepper motor to stop the noise. The AC hasn't shut down since. I doubt there is a connection between the two but maybe the unplugging and replugging of the AC module did it. I did use a good contact cleaner on the plugs and receptacles while doing the work and I think that did the trick.

SickSpeedMonte

Is there a sync process for the HVAC system, like there are for other systems?

mleskovar

Yes, it synchronizes the stepper motors/flaps. Hold down the Recirc and Front windshield buttons for about 10 seconds or until they both start flashing back and forth. When they are done flashing ....you'll hear the various flaps opening and closing and air coming and stopping from the various vents...you have confirmed everything is working, if they continue flashing you have a problem.

And....on board A/Cdiagnostics:

A/C sensor values when holding the EC and REST button for ~10 seconds.

01 In-car temperature sensor.
02 Outside temperature sensor.
03 Heater core temp, left.
04 Heater core temp, right.
05 Evaporator temperature sensor.
06 Engine coolant temperature.
07 Refrigerant pressure in bar (e.g. '4' is 4 bar).
08 Refrigerant temperature.
09 Not used.
10 Heater blower control voltage (normal 08-6.0, meaning .8 to 6 volts).
11 Emissions sensor voltage (to detect atmospheric gases and recirculate interior air).
12 Sun sensor voltage (to shift airflow in car).
20 Control current for auxiliary fan (electric fan on radiator, given in milliamps or mA).
21 Engine speed (x100).
22 Road speed (km/h or mph depending on installation).
23 Battery voltage at terminal 58d (as a percentage of total voltage, e.g. 99.0 = 99%).
24 Battery voltage (e.g. 12.8 = 12.8V).
40 Climate control software version.
41 Climate control hardware version.

SickSpeedMonte

Thank you very much! I wouldn't imagine that synchronizing the stepper motors is going to fix my particular problem though, would you agree?

I dont believe that I have an EC or REST button, this is the HVAC module that is equipped in my car.

(Disregard the smudges on the glass... this was a dealer photo that I saved from the ad)

mleskovar

Hopefully! Listen for clicking an popping noises while it's going through the process. You can feel the air changing direction through the vents with our hands. If it makes noises at one vent and doesn't progress normally (takes too long) then you have a problem with that motor. Good luck!

jcnash

I had the same problem once and didnt get any warning on my dash....but I have an '02 so your car might be different.
I fixed it by driving for a while with all the power consumers off. Since then its worked like a charm.

LILBENZ230

On the facelift cars, press and hold front defrost and recirc buttons at the same time.

Then again, if I were under warranty I'd just bring it in. If it is repeatable now it shouldn't be an issue.

SickSpeedMonte

Just got a call from my SA, and she said that there was a bulletin for the blower motor regulator, and they are replacing it. According to what she said, the symptomes my car has match up to what the bulletin says. I'll report back with the results.