C230 A/C Diagnostic display (Climate control)--How to use - PeachParts Mercedes-Benz Forum

#1 06-26-2002, 11:21 AM

I need detailed information on how to use the diagnostic fuction of the climate control display on a 97 C230.

I found sevral bits on information in the archives and variuos posts on this topic for other models.

If someone has or knows where I can get the complete story on a 97 C230, PLEASE let me know.

Thanks for your time.

JCE · #2 06-26-2002, 12:44 PM

This is what David C Klasse worked out for his 95 C280, and it seems to be the same for my 98 C230, so maybe it works for you:

With ignition in on position, turn climate controls on, then press and hold REST for 5 or so seconds, or until you see an 01 flash then another number will flash (inside temp), then back to one, use the arrow up (defrost) and arrow down (feet) to scroll up and down through the codes.

1. In-car termperature sensor (with aspirator blower)
2. Outside temperature sensor
3. Heater core temperature sensor
5. Evaporator temperature sensor
6. ECT sensor (Coolant temp.), e.g. 12*5 = 125C
7. Refrigerant pressure in bar, e.g. 12*8 = 12.8 bar
8. Blower control voltage, e.g. 16*5 = 1.65 volts
9. Software status of A/C pushbutton control module
15. Selected in-car temperature
20. Version code
21. Engine Speed (RPM), e.g. 6*0 = 600 rpm
22. Terminal 58d (Bat. Volt.), e.g. 99.0 = 99% of voltage
23. Vehicle speed (Kilometers Per Hour)
50. Not used – 00
51. Number of current slip recognition (poly-V-belt)
52. Number of stored slip recognitions (poly-V-belt)

brookspw · #3 08-15-2009, 01:55 PM

Quote:

Originally Posted by JCE

This is what David C Klasse worked out for his 95 C280, and it seems to be the same for my 98 C230, so maybe it works for you:

With ignition in on position, turn climate controls on, then press and hold REST for 5 or so seconds, or until you see an 01 flash then another number will flash (inside temp), then back to one, use the arrow up (defrost) and arrow down (feet) to scroll up and down through the codes.

1. In-car termperature sensor (with aspirator blower)
2. Outside temperature sensor
3. Heater core temperature sensor
5. Evaporator temperature sensor
6. ECT sensor (Coolant temp.), e.g. 12*5 = 125C
7. Refrigerant pressure in bar, e.g. 12*8 = 12.8 bar
8. Blower control voltage, e.g. 16*5 = 1.65 volts
9. Software status of A/C pushbutton control module
15. Selected in-car temperature
20. Version code
21. Engine Speed (RPM), e.g. 6*0 = 600 rpm
22. Terminal 58d (Bat. Volt.), e.g. 99.0 = 99% of voltage
23. Vehicle speed (Kilometers Per Hour)
50. Not used – 00
51. Number of current slip recognition (poly-V-belt)
52. Number of stored slip recognitions (poly-V-belt)

My #7 reading is 19*8--20*5. I am assuming this is too high. If so, this is keeping my compressor from turning on and I need to remove 134a from the system?

Matt L · #4 08-15-2009, 03:52 PM

Quote:

Originally Posted by brookspw

My #7 reading is 19*8--20*5. I am assuming this is too high. If so, this is keeping my compressor from turning on and I need to remove 134a from the system?

With the compressor off? If so, it might prevent the compressor from starting as it is illogical. It would point to a bad pressure temperature sending unit (located on the dryer).

Don't just remove some 134a. Rather, if you're unsure of the fill quantity, recover all of the 134a and recharge by weight to factory specifications.

brookspw · #5 08-22-2009, 05:04 PM

Quote:

Originally Posted by brookspw

My #7 reading is 19*8--20*5. I am assuming this is too high. If so, this is keeping my compressor from turning on and I need to remove 134a from the system?

Ok, after further review -- I'm actually more confused.

If I run the diagnostic at idle, I get about 21*0.
If I run it sitting still, but RPM at 3,000, I get about 23-24.
In neither of the above do I get very cold air at all.

If I run the diagnostic while riding down the road, even if only at 30-40 MPH and maybe just 1,200 rpm...the #7 reading is about 7*5, and I get pretty cold air. Not as cold as I should be but around 50.

I'm thinking there may be more of a sensor/switch/elec issue than a freon thing.

#6 06-27-2002, 04:58 PM

Thanks John and David for the information. However, I guess it is different for a 97 C230. I was able to navigate through the various items starting with "01". While some of the items were the same as listed above in your post, many were not. Also, I had many more not listed above.

Does anyone have or know where I can get the ACC codes for a 97 C230? Does anyonw know if this information is contained in the 'ALLDATA' listing for this car. I would gladly pay $25 to demystify this and a couple of other things.

Thanks for the help.

David C Klasse · #7 06-28-2002, 01:42 AM

Ron,
I'm sorry I haven't replied yet. I have had so much to do, I had your e-mail "Keep As New" so that I would do it.
Anyways, looks like I took too long! I do apologize for that.

As far as the system goes, yours should be fairly similar to mine. John (JCE) says his is similar to my 95, so I assume yours should be too.
However, there are differences, as you have noticed. I do not have information for the exact values/meanings of your 97 C230's PBU.

The only thing I can think of is to send a msg or an email or post directed to SteveBFL. He is very knowledgable in this area and has the resources for all printed data regarding the values.
He was kind enough (10x over) to fax me a list (official MB doc I believe) containing the code meanings to my car.

Good luck. It really is an awesome feature!

echo63 · #8 07-26-2002, 05:15 PM

My parent's 94 C280 is currently undergoing a/c woes. The a/c is not blowing cold air even after a recharge, and all you get is what seems to be outside air. Their mechanic told them that the push button unit needs to be replaced. The price quoted for the part is $840, plus labor. I promised my parents that I will do some research on the a/c problem before they fork out their retirement fund.

Last night I tried this display diagnostics. My question is, how do you interpret the numbers from the climate control display diagnostics? For example, with the engine off but the ignition at ON position, I'm getting numbers that are quite different from David Klasse's example. Some of my numbers are as follows - I'm working from my memory.

7 - Refrigerant Pressure in Bar - 04.3
8 - Blower control voltage - 21.0
9 - Software status of a/c Pushbutton control module - 02
22 - Terminal 58d (Bat Volt) - 0.00

I will try to get more detailed numbers tonight, i.e. standstill vs driving and at HI, LO, 72 degrees. But, I still need to know how to interpret these numbers. For example, is David Klasse's numbers the norm?

Any help you can provide would be greatly appreciated.

Edward

Charles · #9 07-27-2002, 05:13 AM

7 - Refrigerant Pressure in Bar - 04.3
8 - Blower control voltage - 21.0
9 - Software status of a/c Pushbutton control module - 02
22 - Terminal 58d (Bat Volt) - 0.00

Ed,

My 94 C220 should be exactly the same as yours. Your readings look normal while enginer off. 22 represents AC compressor RPM and it is, of course, 00 when engine is off.

Start your enginer then check 22 again to see if it goes up with the engine rpm. If so, the compressor does kick in. If not, the compressor clutch might be out or the PCU controller shut the clutch down due to some error codes there.

To read the PBU's error codes follow the procedure,
Key on with enginer off
Set temperature to LO
Press REST and "Defrost" buttons at a time for over 2 seconds (must be done in 20 seconds from last step"
If you see the LED on recirc button is flashing at 1Hz freq and screen shows "diR" you are in error code retrieving mode.
Press AUTO to read a contineous error codes at a time
Continue press AUTO and write all codes in your note until screen shows End

Now press AUTO again to read the intermittent codes.
Same procedure as contineous code reading above until screen shows End.

Make sure you log all the codes in your note. Let's see what you get.

Now the procedure to clear these codes,

Press '^' and 'V' at a time the screens shows "---". Codes being cleared.

The last step is somewhat different from what I experienced in my car. Manual says press ^ and V again to exit but I never success. So I simply turn key off, then start engine again. Turn AC on to see if you get cool air back. You can also check 22 to see if the compressor is running.

Hope it helps.

Charles from Taiwan

Charles · #10 07-27-2002, 05:29 AM

This is what I got from my Chinese version repair manual.
After August 1995 MB changed diag program and the AC system.

1. In-car termperature sensor (with aspirator blower)
2. Outside temperature sensor
3. Heater core temperature sensor
4. Evaporator temperature sensor
5. Engine coolant temp. sensor
6. Refrigerant pressure in bar, e.g. 12*8 = 12.8 bar
7. Blower control voltage , e.g. 16*5 = 1.65 volts
8. N/A for 1995 model, Refrigerant temp. sensor for 1996
9. N/A
10. Blower control voltage (seems the same as 7, not sure)
20. Aux fan control current, 7=7mA
21. Engine Speed (RPM), e.g. 6*0 = 600 rpm
22. Vehicle speed (Kilometers Per Hour)
23. PBU illumination adjustable voltage, 88=88% input voltage)
40. Softare status
41. Hardware status
42. Version code 1 (ex.03)
43 Version code 2 (ex. bEn=gas engine)
50,51,52 not used
53. Compress status (On-Off)

JCE, I copy some of your typing. Hope don't mind!

Thanks
Charles

stevebfl · #11 07-27-2002, 10:04 AM

Well, as to the 58d, I'm pretty sure that is the illumination input. It should go up when the lights are on and the dash illumination is set highest.

The early and late systems are definitely different. The biggest change being the size of the display. Being at home I can't lay out any lists but the extent of diagnostics goes beyond actual values and fault codes to the activation of air flaps in the dash.

I wrote an article for "Import Car". It can be viewed at my site:
http://www.continentalimports.com/ser_ic40142.html

The article is specific to a 97 210 chassis, but the information is similar for all chassis.

echo63 · #12 07-27-2002, 08:03 PM

Thanks Charles & Steve for your help. I had the opportunity to study the problem in detail, and the diagnostic told me that the compressor was not running, even with the engine running. I got the fault codes and everything and I was about to post the result when I noticed that a connection was loose at the compressor. Presto, and the a/c is working fine now. I guess it must have been a power supply or something to the compressor.

Anyhow, I'm glad my parents have saved big bucks, and kinda pissed off that the mechanic may have been trying to take my elderly parents for a ride. Well, I guess it's time for a new mechanic.

Charles, are you in Taipei? I was an investment banker covering Taiwan & Korea a few years back, and visited Taipei & Shinzhu Science Park several times. Great tasting food, extremely hot weather. Always stayed at the Sherwood. Enjoyed the snake alley but didn't have the courage to drink the snake drink. Thanks again for your help.

Edward

Charles · #13 07-28-2002, 01:31 AM

Ed,

I am glad to know you got the cool air back. Yes, when AUTO being pressed the PBU sends a 12V voltage to compressor's electromagnetic clutch to engage the compressor.

I am a program manager leading a design team design server product for Compaq (now it becomes HP). Sometimes I will visit Houston Compaq headquarter to discuss product issues. In Taiwan I live just the half way between Taipei and Hsinzhu science park. Only 40 minutes drive to Taipei from my home. I was graduated from Chiao-Tung Univ. which sits right next to the science park.

To save precious storage space in this great site, let's talk personal things by email, OK!

I am happy I could help.

Charles from Taiwan

stevebfl · #14 08-01-2003, 12:02 PM

Those aren't codes, they are actual values. The first shows the signal voltage to the fan controller (I presume) and it is likely the fan wouldn't be on with the engine and AC off.

The second is the voltage signal for dash illumination and would have no value unless the lights were on.

blackmercedes · #15 08-01-2003, 02:02 PM

Check the evaporator temp sensor readings. If the temp reading is anything other than around 4-6C with the engine running and the AC system not on EC mode, than you probably have a problem. Evap temp sensors failure is not an unusual reason for AC difficulties.