99 C280 Component Questions
01-23-2009, 05:50 PM
#51
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2014 ML350 4Matic
Compressor squeaks and smokes? Perhaps the compressor is locking up and the clutch is smoking. Obviously this doesn't sound good. I would address that issue before the N65/1.
This is also a good time to go back and carefully look at the live data and see if this is a problem on the refrigerant side.
This is also a good time to go back and carefully look at the live data and see if this is a problem on the refrigerant side.
01-23-2009, 07:40 PM
#52
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95 C280
Agreed.. The compressor was an unexpected mess...
I ran all of my weekend runs today. So, I will be free to dedicate the entire day for figuring out the HVAC Heating & AC system.
Do MB sell a compressor clutch rebuild kit? I hope so...
I ran all of my weekend runs today. So, I will be free to dedicate the entire day for figuring out the HVAC Heating & AC system.
Do MB sell a compressor clutch rebuild kit? I hope so...
02-03-2009, 01:34 PM
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Well I removed both tires and completely checked the wheel well components.
The vacuum tank on the pass side is holding vacuum without leaks.
The drivers side Aux Fan Controller/Resistor appears fine and fairly new. Could not locate a test procedure for the unit to validate its in-spec.
This is way more difficult than I orginally thought.
The Error Code testing procedures does not matchup to the pinout on my HVAC Control plugs.
Thus, I cannot complete the testing for the error codes displayed.
The compressor appears to be functioning again.. Dont know about the smoking.
Went to my local MB mechanic to put on his Star Diagnosis.
His Star not working currently and he's not expecting a repair for a few weeks.
I will probably wait as this shop is half the cost of other local MB shops and 80% lower than the dealer.
We swapped the Fan Controller with a known good one for a test yesterday.
We cleared the code and sofar it hasnt returned. Hopefully this will fix the problem..
Update:
Error Code returned...
HVAC still in default mode...
The vacuum tank on the pass side is holding vacuum without leaks.
The drivers side Aux Fan Controller/Resistor appears fine and fairly new. Could not locate a test procedure for the unit to validate its in-spec.
This is way more difficult than I orginally thought.
The Error Code testing procedures does not matchup to the pinout on my HVAC Control plugs.
Thus, I cannot complete the testing for the error codes displayed.
The compressor appears to be functioning again.. Dont know about the smoking.
Went to my local MB mechanic to put on his Star Diagnosis.
His Star not working currently and he's not expecting a repair for a few weeks.
I will probably wait as this shop is half the cost of other local MB shops and 80% lower than the dealer.
We swapped the Fan Controller with a known good one for a test yesterday.
We cleared the code and sofar it hasnt returned. Hopefully this will fix the problem..
Update:
Error Code returned...
HVAC still in default mode...
Last edited by ScottyP; 02-04-2009 at 04:58 PM. Reason: Update
03-10-2009, 11:27 PM
#54
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95 C280
Hey, to each his own 
but I just want others to know they do have a choice (at least with a '99) and it is really nice in this cold weather to get lots of heat coming out. I know that I have had heat coming out of the center vent since this car has been new, so that negates age related issues in my case. I just checked my manual and it refers to setting both the center vents and the side vents when setting the heat function. Heat is basically equal too, so know it isn't leaking or residual heat.
I did find a diagnosis document in WIS that helps troubleshoot heater function problems. It notes that when you get "side outlets, heated air" + "center outlet, no heated air" that the "possible/cause remedy" is/are "23 -> 3.0, 4.0, 5.0" but I am not sure what those mean. I would have to dig into WIS more to find that out.
but I just want others to know they do have a choice (at least with a '99) and it is really nice in this cold weather to get lots of heat coming out. I know that I have had heat coming out of the center vent since this car has been new, so that negates age related issues in my case. I just checked my manual and it refers to setting both the center vents and the side vents when setting the heat function. Heat is basically equal too, so know it isn't leaking or residual heat.I did find a diagnosis document in WIS that helps troubleshoot heater function problems. It notes that when you get "side outlets, heated air" + "center outlet, no heated air" that the "possible/cause remedy" is/are "23 -> 3.0, 4.0, 5.0" but I am not sure what those mean. I would have to dig into WIS more to find that out.
I decided to replace my Climate Control Unit (N22) with one from a 96 C280 and I now have working vents. I now have all functions: Defrost, Floor, Dash, & Floor/Dash combo.
Finally, heat thru all of my vents INCLUDING heat from the Center Vents!!
Thats right !! I get real HEAT from the Center Vents. Its great that my right side will finally have heat..
Thanks for the info xvvvz
Last edited by ScottyP; 03-11-2009 at 10:15 PM.
03-11-2009, 12:34 AM
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Update
Well, my MB shop got their computer working again and I finally got my car in the shop for analysis..
Results:
1. As mentioned above, the Climate Control Unit was defective.
This was causing the Air Distribution being in the default Defrost mode.
Found a known good used Push Button Control unit and installed it.
Now, all of my Vent Positions are working. 
No More cold feet, now heat in the rear of car, and heat from all dash vents.
2. But, not all good news. Still have the DTC code: 421 Pulse module
We could not activate the fan. Thus, my Fan is not cooling the radiator...
Using the Star software, we entered the AC module and selected Fan activation.
It has 4 setting for the Aux Fan. All selections will not start the fan.
After 4 hours of trying, we stopped...
Testing performed:
- Used a known good Radiator Fan & Aux Fan Control Unit - No Activation
- Pulled the plug on Coolant Temp Sensor - Fan runs at Full Speed (Default)
- Tested the harness cable between Fan & Fan Control Unit - Cable is good
- Tested Fan Startup amp draw - found within spec
Im so stumped here... What is causing this error code???
One of the sensors, another unknown control unit, pulse signal, WHAT????
NOTE: There is an audible Click (possible relay) upon first activation. Cant determine location..
Planning to do some wire testing/tracing.. Power, grounds, input/output signals, etc.
Not an easy task but Im trying to determine where the activation signals are interrupted (failure point).
Where can I find the voltage and ohm resistance for testing sensors & control units?
I have AllData CD & online account and the WIS CDs.
As usual, any help is greatly appreciated..
Results:
1. As mentioned above, the Climate Control Unit was defective.
This was causing the Air Distribution being in the default Defrost mode.
Found a known good used Push Button Control unit and installed it.
Now, all of my Vent Positions are working.
No More cold feet, now heat in the rear of car, and heat from all dash vents.
2. But, not all good news. Still have the DTC code: 421 Pulse module
We could not activate the fan. Thus, my Fan is not cooling the radiator...
Using the Star software, we entered the AC module and selected Fan activation.
It has 4 setting for the Aux Fan. All selections will not start the fan.
After 4 hours of trying, we stopped...
Testing performed:
- Used a known good Radiator Fan & Aux Fan Control Unit - No Activation
- Pulled the plug on Coolant Temp Sensor - Fan runs at Full Speed (Default)
- Tested the harness cable between Fan & Fan Control Unit - Cable is good
- Tested Fan Startup amp draw - found within spec
Im so stumped here... What is causing this error code???
One of the sensors, another unknown control unit, pulse signal, WHAT????
NOTE: There is an audible Click (possible relay) upon first activation. Cant determine location..
Planning to do some wire testing/tracing.. Power, grounds, input/output signals, etc.
Not an easy task but Im trying to determine where the activation signals are interrupted (failure point).
Where can I find the voltage and ohm resistance for testing sensors & control units?
I have AllData CD & online account and the WIS CDs.
As usual, any help is greatly appreciated..
Last edited by ScottyP; 03-11-2009 at 12:38 AM.
03-11-2009, 10:08 PM
#56
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95 C280
Final Update
All Problems Fixed.. At Last ! !
I swapped out the Climate Control Unit for one from a 98 C280.
All communications to the fan is now resolved and all of the HVAC functions are working properly.
THE 421 DTC ERROR IS FINALLY GONE ! !
Amazing that only 98 or 99 C280 Climate Control Units will work. My C280 engine is a 112.920 ME-2.0
The Climate Control programming must be different for ME-SFI systems.
Thanks to everyone here that helped me with this problem.
I swapped out the Climate Control Unit for one from a 98 C280.
All communications to the fan is now resolved and all of the HVAC functions are working properly.
THE 421 DTC ERROR IS FINALLY GONE ! !
Amazing that only 98 or 99 C280 Climate Control Units will work. My C280 engine is a 112.920 ME-2.0
The Climate Control programming must be different for ME-SFI systems.
Thanks to everyone here that helped me with this problem.
11-21-2010, 11:10 AM
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95 C280
