JimVonBaden

Driving along today, AC on, I came across a couple of idiot 20 somethings that decided to cross a 40 mph street without looking. I slammed the brakes, ABS activating, and horn blowing. They barely looked up as I nearly ended them.

Anyhow, seconds later the AC went off and the front defroster went full on high with heat. Nothing I did would shut it off including turning off everything. Even a restart didn't help.

Ideas?

DRACO

Pull the defrost fuse until you can determine which component failed.

Coruscator

This is the 'courteous driving monitoring system' or CDMS. Its a feature introduced
on all U.S. CLK500's from 2005 on-wards.

The system monitors your driving style and the environment around
the car and if it decides that a breach of the rules has occurred then it
activates a punishment.

If its a hot day then your heaters and blowers will automatically switch on
and if its a cold day your blowers and A/C cooling will automatically switch on.

These systems will continue to run until the CDMS decides you have learned
your lesson and that you intend to drive more carefully in the future.

Coruscator

Sorry, couldn't resist.

Hooking up a star diagnosis would probably throw up an error code if,
there is one, which will pin-point the fault.

Have you tried disconnecting the battery, leaving it off for 15 minutes, then reconnect?

I'd do the battery thing first. If it doesn't work then - star will save you time
and money and should put you on the right track.

I would say that the emergency stop you performed and the fault you now have are,
most likely, unrelated.

gixxerboy

thats is strange, try going backwards and slamming the brakes.

I am curious to see what caused that

DanielFD

This has happened with me, not exactly the same scenario. I had my dash apart and i turned on the AC, and that car switched to defrost at full heat. turned out the small plug (as opposed to the main plug) at the back of the ac controls wasn't plugged in correctly. It might have gotten loose. Weak system really, every since then it happened a couple times, luckily the idiot who tried to repair my car before i owned it had broken off the plastic tabs that hold down the main console so basically i used to just pull it out and plug it back in, without taking anything else apart. Useful really for hiding things.

JimVonBaden

Now that sounds like a possibility! It literally happened right after I slammed on the brakes. I'll check this out!


Thanks!

JimVonBaden

I went to check on the plugs yesterday, but decided to run it and see what it does first. Mostly because access to the plugs is not very simple apparently. The damn thing works fine. That makes me nervous. I like solid issues identified and fixed. Intermittent issues are a PITA.


Any ideas other than the plugs?

Coruscator

Nah, it's easy to get to Jim.

1. Put your key in and pull the gearstick into neutral

2. Open the ashtray flap

3. Grip the front edge of the gearstick surround and pull upwards to remove it.

4. Under the gearstick leather there is a plastic locking nut. Twist this
a quarter of a turn, then pull the gearstick and surround up and off.

5. There are two plastic clips on both front edges of the ashtray. Lever
these two forward to remove your ashtray and pull the two electrical
plugs out so you can put it to one side.

6. Under where the ashtray was there are two screws secruring your
A/C control unit into place. (torx 20) Remove these. (The screws are on the
outside edges of the A/C unit, there are two other screws in this area but
they are for removing the center console, ignore these)

7. Grasp the A/C control unit and pull it towards the gearstick, it'll pop out.

8. You should now be able to see the two plugs on the back of your A/C unit.

Coruscator

I've been thinking about this.

Like I said earlier, I don't think your em-stop and the fault are related.

The plugs on the back of our A/C units are secured into place really well.

The 'harness' plug has a grey 'fold over' clip which holds it in place.

As long as this fold over clip is installed correctly, there is no way it can
fall out. Plus its quite difficult to wrongly plug this plug in.

The other smaller plug, which while extremely unlikely, has more of a
chance of falling out if not plugged in fully.

But, (and correct me if i'm wrong), I understand that this smaller plug
is used to control your stepper motors. So I don't think it would put your
system into defrost/full blower mode.

Hmmmm, its an odd one.

JimVonBaden

Wow, thanks! I was looking to go in from the side. That should make it easier.

JimVonBaden

That is why I hate intermittent problems. Hard to nail down, often a loose wire, occasionally a faulty control unit, rarely obvious even when you think you have it fixed it often is not. Frustrating for sure.


What else could cause this reaction? Once the blower turned on, no amount of button pushing, even restarting the car, would even shut it off. The whole control panel was turned to off and the heat/blower was still blowing tornado speed. Even could be heard from outside the car quite loud.

Coruscator

Is it working now?

You said in your earlier post that it was (intermittently).

Can you try the A/C reset thingy?

Hold both recirc and windcreen buttons on the A/C unit for about 30 seconds
or until both lights start to flash.

This will test your A/C, blowers and stepper motors.

If it stops after about 45-60 seconds then all is well.

What could cause this?

A worn or broken relay, water in electrics, a short somewhere,
gremlins? (don't feed them after dark).

Your guess is as good as mine, Jim.

You could try the removing the battery for 15-20 minutes, this'll reset stuff
and it might not happen again. Plus its free too. :0)

I'd recomend star but that'll cost you obviously.

Its a fault Jim, but not as we know it. :0)

JimVonBaden

Just because you went to all the trouble to describe it, and to verify it, I pulled the controller out. It was super clean, dry and well connected. I doubt it had been touched in the past. Photos later.

I also performed the reset per your instructions. It appeared to work as you described.

The system is currently working fine. I ran it, with multiple changes, for a half an hour, and everything worked fine.

Thanks for your help. We shall see what happens next.

JimVonBaden

Just a follow-up. The system is still working just fine, no issues at all. It may have been the sensor under the interior lights being dirty. Who knows?