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

brookspw · #1 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 · #2 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 · #3 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.