My HVAC system in my 99 C280 is in the Default mode: Air Circulation from the Defrost & Side vents only. This is with all HVAC Control settings.

So today I pulled the codes using HVAC display. Heres the errors found:

DTC Codes
Continuous Fault
24 1
42 1
Intermittent Fault
41 1
41 6
41 7
41 9
End

These codes are not shown for AC/Heater codes..
Where do I find the definition for these Error Codes?
Are they the same as the ODBII codes?

Also, heres my HVAC Real Time Values:

Real Time Values
01: 74F . | . 40: 03
02: 44F . | . 41: 03
03: 116 . | . 42: 03
05: 101 . | . 43: 6-C
06: 204 . | . 50: 114
07: 05 6. | . 51: 80F
08: 102 . | . 52: 32F
09: 50F . | . 54: OFF
10: 335 . | . 60: OPE
20: 00 . . | . 61: 0.9
21: 060 . | . 62: 0.9
22: 000 . | . 63: 0.9
23: 000 . | . 64: 0.9
24: 14.0 .| . 65: 0.9
. . . . . . .| . 66: 0.9

Thanks for any help..

Code 241 is related to the amount of refrigerant in the system.
Code 421 suggests that the aux fan control module is having issues.

The actual values look good.

__________________
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Thanks Doc.
Where did you find these codes??
I have & searched EPC/WIS & AllData with no luck...

I cleared the codes and drove 120 mi. The 421 code returned.
Today, I will find the aux fan control module and investigate the fix/repair.

Update: Just looked, I dont have any Aux fans ! ! !
Did the 99 C280 leave the factory with Aux Fans??

Aux fan OR engine cooling...code suggests that the ELECTRIC fan control is having issues.

Module is behind left front wheel under a plastic cover on frame rail.

__________________
MERCEDES Benz Master Guild Technician (6 TIMES)
ASE Master Technician
Mercedes Benz Star Technician (2 times)
44 years foreign automotive repair
27 Years M.B. Shop foreman (dealer)
MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)
Retired Moderator

Once I find it, What kind of testing can I do?
Voltage values or ohm values?

Hey all..

I have replaced the Electric Fan Control unit and replaced both Fan fuses.
Cleared the HVAC fault codes and took a short test drive.

NO LUCK..
Code 421 returned immediately.. All other codes are gone.

What else can I do to remedy this code? Help...

MB Doc,
Any ideas on the next steps...

I am no doc, but check your vaccum pump (under back seat on 320). I had similar problem on my e320, and it was my pump....yes pump that controls your doors.
I am not sure if that is your problem, but it is worth looking at.

Good Luck.

Thanks 98mbe320
I will check the vacuum pump today. My pump is in the trunk passenger qtr panel.
But the HVAC is still looking for an electrical signal from the Radiator Fan Control Unit.. Code 421

Question: Was your door locks working properly when you replaced the pump?

Problem fixed..

It was the HVAC Push Button Control Unit that was bad.
Replaced it and all is well now.. No codes & all HVAC functions are working..

Thanks to everyones help..