jevsays

Recently, my a/c gave out so I took it to a nearby a/c specialist and came to find out the ALLDATA report said there may be effective refrigerant line.

Has anyone came across this issue before? My car is just over 62k miles, 2005 Sedan Kompressor.

He also claimed that the compressor for the a/c wasn't working and there doesn't seem to be an electrical issue from the diagnostics. I'm stuck here spending money but I just wanted to get some more insight in case I do have to buy the part and pay roughly 300$ for the labor to install AND that still may not be the last piece of the puzzle to find out if the a/c will work. Please help!

ncmudbug

First I assume you didn't hear a screeching that sounded like a belt slipping or tires rubbing against a rubber floor - that might indicate that the sprag bearing took out your compressor. Do a search on sprag bearing.

That not being the case, I had my compressor go out (that's what they told me - not that I think they were lying) when my '05 C230K was about 40K miles old.

It doesn't seem like the A/C is necessarily a weak unit (on average for most owners) but I've had to replace mine twice.

A good indy is your friend!

jevsays

Nope, no such sounds... Just hot air and somewhat "cool" air.


Thanks!

Venne-70

Is the amount of refrigerant / pressure checked.
My car W203 year 2003 mileage 15.6k miles was added to the refrigerant (R134a) 0.755kg and oil 35ml to A/C system
Refrigerant and oil was added to the mercedes service


My boy car Audi A4 the same problem. Just hot air and somewhat "cool" air.
Resolved by adding refrigerant.

SickSpeedMonte

Usually the compressor kicks on when the pressure is low. I wonder if these cars are sophisticated enough to know when it's too low and then they don't kick on the compressor to save it from wearing out?

Venne-70

Thus I understand it, the system protects itself.


Climate Control / Refrigerant Pressure and Temperature Sensor (B12/2) / Function

Detecting the refrigerant pressure
The refrigerant pressure and temperature sensor detects the refrigerant pressure and passes the detected value through the front signal acquisition and actuation module and the CAN BUS to the pushbutton control module. This value is compared with a stored temperature pressure curve. The refrigerant pressure and temperature sensor operates within a pressure range of 0 to 35 bar.
Shutting of the refrigerant compressor
The refrigerant compressor is shut off if the following values exist.

• Refrigerant pressure < 1.8 bar =
  refrigerant compressor OFF
• Refrigerant pressure > 30 bar =
  refrigerant compressor OFF

Engaging the electric engine/AC fan
The electric engine/AC fan is operated if the following values exist:

• Refrigerant pressure <12 bar =fan OFF
• Refrigerant pressure >20 bar =fan ON (100%)
• Refrigerant pressure 12 to 20 bar = stepless linear speed increase of fan (20-100%)

Detecting the refrigerant temperature
The refrigerant pressure and temperature sensor detects the temperature of the refrigerant and passes the detected value through the front signal acquisition and actuation module and the CAN BUS to the pushbutton control module. This value is compared with a stored temperature-pressure curve and the refrigerant level determined on the basis of this.
If the refrigerant level is too low, the refrigerant compressor is switched off by the pushbutton control module through the CAN BUS and the front signal acquisition and actuation module. The system is now in the EC mode. The AC mode is not operational again until after erasing the fault memory in the pushbutton control module. The refrigerant pressure and temperature sensor operates within a temperature range
of -10 °C to +90 °C.


Text this link: http://bayhas.com/mercedes/w203/contents/home.html

Page:
Climate control

Page:
Refrigerant pressure and temperature sensor (B12/2)
press the at the top of the link function

sammydragon3

another thing is u can turn the compressor off and on with the touch of SDS

jevsays

The mechanic I took it too say the pressure was low for the HIGH and LOW valves...

He added the freeon and dye and said didn't see any leak but was uncertain because the compressor didn't come on because it wasn't getting enough pressure through the system for it to kick on.

295$ labor to SEE if refrigerant lining is constricting airflow...and if purchased/replaced (not exact cost figure) it STILL may not be the answer to my a/c solution.

jevsays

Forgive me if I'm wrong but could I possibly take to the dealership and have them "erase the fault memory in the pushbutton controle module?....

trevG

Hi,

I have a similar problem on my w204 C63, my fan comes on full blast on start up and stays on.

My refrigerant sensor reads 22bar, both when the sensor is in the AC and when I have it plug in at atmosphere pressure. So I thought I had a faulty Ac pressure sensor and replaced it.

The new sensor reads 35bar both when its in the AC and at atmosphere pressure.

I have tested ground and the 5v input to the sensor and all is good

If I disconnect the signal wire from the ac sensor I get 22 bar and if I totally disconnect the sensor I get 6000bar.

Where does the signal wire come from the front SAM? Is there maybe a wiring diagram?

Mario61

Hello trevG, did you fix the fan issue? I have same problem in w211 and still working on it. What is the reading on the B12/2 the refrigerant temperature sensor for the temperature? My scanner reads it as -146.3 F or -99 C.
Thanks