Real quick I'm not sure if the heater should be blowing harder but from other cars I have been in with a heater they blew pretty hard. I know the back seat that has the seperate heater blows like a damn tornado. But how hard should the front heater blow?


Also what is the best setting to put it on? Since Im very confused with the buttons? I know they have the ec button, the car with the circulation button, the regular button that is labeled 0? ANd then the setting on the vents should go all the way to the left? Where the bigger squares are next to the dot?

Any advice?

The blower should be capable of blowing you into the backseat, where the rear blower will take over and shove you into the trunk.

To test the blower, press AUTO - EC only shuts off the A/C compressor, and unless it's REALLY cold outside, you'll need it's help to moderate the temperature of the air coming from the heater.

Set the fan speed dial (in the very center of the climate control) to AUTO. Rotate both temperature dials up to the red detent position - I think you'll see 90F in both temp windows. The car must be showing at least some small amount of heat on the temp gauge for this test to be accurate.

Dials in the center of the dash control only airflow to the left, center 2 and right dash vents - they have no effect on the airflow from the heater, which should produce most volume from the vents in the knee bolsters on the drivers and passenger side. Air also blows into the doors, so there's a seal at the end of the dash for those ducts. You should get a small amount of "bleed" air from the outboard dash vents, and also some bleed air from the defroster vents.

Give the system a few seconds to get it's bearings and you should get full force blow from the fan.

If you don't get a huge increase in air volume after 5-10 seconds, rotate the fan speed dial to HIGH and see if the fan speed changes. If it doesn't - something's not right.

If you get good blow from the A/C vents (set the temp dials to the blue detent), but not from the heater vents, it's possible that something's not right with the dampers inside the ducting system.

You can pull trouble codes for the A/C right from the Climate Control unit - it's quick and easy to do. Here are the steps:
1) Key OFF
2) Left temp wheel - rotate to red detent. If the wheel seems to want to go all the way around (mine used to until I got the unit fixed), you should still feel a click around the point where the end of the red stripe becomes visible. I think the temp window will show HI when the dial is in the correct position.
3) Right temp wheel - rotate to blue detent. Same note applies if the wheel rotates freely through 360 degrees of rotation. I believe you'll see LO when the dial is in the right spot.
4) Turn ignition key on to 2nd position - no need to start the car, but all the warning lights on the instrument cluster should be illuminated.
Press the left AUTO button.
5) Within 20 seconds, simultaneously press the REST and 0 button for more than 2 seconds and release.

You'll hear some clicking, the fans on the front of the radiator will cycle on to full power very briefly, and then any trouble codes stored by the A/C will be displayed in the temperature windows.

DTC codes are 3 digits in length - the left window will show E, plus the hundredths digit. The right window will show the tenths digit and single digit. For example, if the code is 125, you'll see E1 in the left window and 25 in the right window.
Press the RIGHT AUTO button to scroll through the list of trouble codes. Don't delete any of them yet.

A WORD OF WARNING - It is possible for a bad climate control unit to report DTC's for circuits/components that are working just fine. My CC was "flaky" - when I'd start the car, the fan would run gangbusters for a few minutes, then drop off to low speed, regardless of where I set the fan speed switch, or what temperature I selected on the dials. The DTC's told me I had a faulty duovalve, a faulty ETC sensor, a bad left temperature dial and a bad idle speed-up diode. I replaced the duovalve at an ultimate cost of over $500 because I assumed the DTC was correct, and I wasn't getting heat on the driver's side of the car.

I had the CC unit rebuilt - (send me a private message for the source) and once re-installed, I checked DTC's. None were reported. All of the components that were supposedly bad (except for the temperature dial), were actually OK, it was the CC that was bad. I now believe that there was nothing wrong with the duovalve, it was the bad left temperature dial that was preventing my getting heat on the driver's side.

You can also test the dampers, there's a different set of buttons to push to access this test protocol.

Spend $20 and get an alldatadiy.com membership for your car - TON's of diagnostic tests available there - that's where I got the instructions for the DTC test I just posted with this message.

Automatic Climate Control is just like your house A/C (although, since you live in SF, you may not have A/C ).

When the car is cold, setting the dials to 90 doesn't make it heat up any faster than leaving them at 75 or whereever you'll be most comfortable. Likewise, when the car is hot, setting the dials to 60 doesn't make it cool off any faster. There's a finite amount of heating and cooling that can be created by the system. The fan will speed up or down to increase the rate of cooling or heating. Max fan speed will provide all of the heating/cooling that is available for any given climatic condition in the car. If the inside of the car is 105F, and the temp setting is 75, the car will cool down just as fast as if the temp setting is 60.

Set the dials where you want the temp to be, and (more or less), leave the system alone.

Of course, if you're more comfortable with heat in your face instead of on your feet, you can press the various buttons to move the location of the airflow. In general, the car will provide A/C out of the dash vents, and heat out of the floor vents. Selecting Defrost will send all (or most all) of the airflow to the vents at the base of the windshield.

The red & blue buttons in the center dash vents make the most "sense" (and I use that term loosely) when the car is in heat mode. Pressing the red button will send heated air out of the center vents. Pressing the blue button will send outside (unheated) air out of the center vents. These buttons work in an either/neither mode. Red only, Blue only or neither. When the car is in A/C mode, the red button seems to function the same as the blue button - non-cooled air is delivered from the upper vents. (At least that's what I've been able to determine in the short time I've owned the car - it may be a totally different story when it's 100F here in Houston next summer.).

You might want to share the year of the your W140! At some point the climate contol went electronic with buttons and no dials.

Steve

I'm familiar with this board member - it's a '92 600SEL, hence my detailed replies for a '92 CC unit - but thanks for checking.

Brian, nice write-up. I have problem on my 95-S500 CC unit. The warm/hot air can not be adjusted on the passenger side-either turn it to HI/hot or no warm air in between 72 to 90 degree. The cool/cold (AC) setting is working. Any suggestion.

PM regarding the unit rebuilt sent.
Thanks.

Yea sorry about that it's a 92 s600 like brian said. I will be checking what he said about the fault codes and what settings to use. I will report back in a little bit. Thanks.

OK it looks like it worked, I got 3 codes from the system.

e151
d151
e000


NOw how can I check what codes these are?

any idea?

Code 151 = "Coolant Circulation Pump (A31/1m1) Short or Open Circuit". This is part of the Duovalve (front) assembly.

Here is an article on the rear duovalve for a S600. It may help a little...

http://v12uberalles.com/Rear_AC_System.htm

__________________
1995 S600, 1 of 618 (sold)

"Speed is just a question of money...how fast you wanna go?"

LONG LIVE THE W140!
Visit my Web Page at www.v12uberalles.com

Last night I tried every possible setting to get a lot of heat to come out from the front. But no luck. So Im figuring it has to do something with the
Coolant Circulation Pump???


Anyone have an idea how hard or how expensive this repair would be if I took it to a shop?

It's a pretty easy job. Remove the front left plastic cover to access the coolant circulation pump and duovalve assembly. While the engine is warm and running, and the CC is set for heat, touch the coolant circulation pump to see if it's working. You should feel a slight vibration. Or, with everything off, remove the connector from the pump and check if there is continuity between the pump terminals. If there isn't, the motor windings are open. Time for a new pump. Pump can be bought for around $190 from online sources. MB manual states 0.8 hours to do the work.

Look through the link I attached in my earlier post. Although it describes the rear heater system, it will give you a better idea of what you're dealing with. The front is similar.

Attached Thumbnails

   

__________________
1995 S600, 1 of 618 (sold)

"Speed is just a question of money...how fast you wanna go?"

LONG LIVE THE W140!
Visit my Web Page at www.v12uberalles.com

Sounds like your blower regulator may have 'died'! Check out this thread for more info.

A/C blower's output is low . . .


If you want to check AC codes in the future, check out MENU#15. Both operational checks and diagnostic code readout procedures are there.

__________________
Regards . . . . JimF
-------------------
'94 S500 Cpe

Visit my Mercedes Web Page

Hey jim It sounds exactly like the blower regulator went out. Where did you end up buying the part from? And did you do the work yourself? If so how hard/long did it take?

As may have seen on my pages, I do most of my work at Exclusive Motors. Pat gets parts at a good price so, if I remember correctly, he got it for me for about $130 or so?

The reg is a piece-of-cake to replace; simply remove the 'air-plenum' (a few long screws) and after lifting it off, the top of the blower w/ the reg is there.

Just don't forget the silicone grease (s/g); need to use it to mount the new reg to blower frame. The s/g serves to transfer the heat. You can get some at Radio Shack if need be although if I remember correctly, the new one comes with it 'pre-greased'??

__________________
Regards . . . . JimF
-------------------
'94 S500 Cpe

Visit my Mercedes Web Page