[hgroth]

I got a 1997 S500 and the A/C compressor is not turning on and in the A/C control the EC button stays turned on and
cannot be turned off which keeps the compressor turned off. In the diagnostics menu I can see an A/C pressure of 4 bar.
Why is the EC mode turned on and cannot be turned off, is this an issue with the compressor?

 

[quakercity]

Could be the controller. You should be able to find one on EBay or used parts sites.

 

[Drbobme1]

WHEN READING THE 4 BAR PRESSURE WHAT WAS THE OUTSIDE TEMPERATURE?

 

[hgroth]

WHEN READING THE 4 BAR PRESSURE WHAT WAS THE OUTSIDE TEMPERATURE?

I checked it while the car was sitting in the garage, maybe around 85F

 

[Drbobme1]

Possible very low freon level. Charge with R134 until above 7 bar and compressor should start.

 

[hgroth]

Possible very low freon level. Charge with R134 until above 7 bar and compressor should start.

Thanks so much, I had no idea what the pressure should read, but was also thinking about the
pressure since I had to add some R134 about 10 years ago. Must be a very small leak somewhere

 

[Drbobme1]

You may have to reset any fault codes before the EC light goes out. A search of BenzWorld for A/C Fault codes will give the procedure to erase them.

 

[hgroth]

You may have to reset any fault codes before the EC light goes out. A search of BenzWorld for A/C Fault codes will give the procedure to erase them.

I have not seen any fault code, where can I see the fault codes ?

 

[Drbobme1]

Search Benzworld for A/C fault codes for procedure.

 

[hgroth]

Search Benzworld for A/C fault codes for procedure.

I don't get any fault codes at all, with the OBD2 scanners that I have and the climate control diagnostics
function, only shows the values for each sensor and all seem to be working.

 

[Drbobme1]

OBD2 Scanner does not show codes for A/C system. Procedure will be found if you search Benzworld for A/C Fault codes.

 

[hgroth]

OBD2 Scanner does not show codes for A/C system. Procedure will be found if you search Benzworld for A/C Fault codes.

I must be doing the search incorrect, but I can only find a list of the fault codes and besides the OBD2 cannot
find any other mention to where I find specifically the AC codes and how to reset any codes.

 

[Drbobme1]

Do not use the OBD2 tester to find codes in the A/C system!!
Search this: W140 A/C fault codes

 

[Drbobme1]

Do not use the OBD2 tester to find codes in the A/C system!!

 

[hgroth]

Do not use the OBD2 tester to find codes in the A/C system!!
Search this: W140 A/C fault codes

I did that search and also where to find the ac fault codes and in so far in 10 pages of search
results, I can find the code list but no mention where to access the codes and to reset them.

 

[jal1224]

Here:

STAR TekInfo

They can also be tested using the 38 pin connector under the hood, using Mercedes STAR diagnostics. The OBD II connector only works for engine diagnostics. Everything else uses the 38 pin.

Jon

 

[hgroth]

Here:

STAR TekInfo

They can also be tested using the 38 pin connector under the hood, using Mercedes STAR diagnostics. The OBD II connector only works for engine diagnostics. Everything else uses the 38 pin.

Jon

Here:

STAR TekInfo

They can also be tested using the 38 pin connector under the hood, using Mercedes STAR diagnostics. The OBD II connector only works for engine diagnostics. Everything else uses the 38 pin.

Jon

I just got a 38 pin to OBD2 adapter but I have not tried it. Maybe that will work

 

[jal1224]

It won't work. Unless the tester is specifically designed for the early Mercedes, and has a multiplexer function, "adapters" are useless.

Jon

 

[Drbobme1]

Try on Benzworld search W140 Forum "
Automatic Climate Control Diagnostic Trouble Code (DTC) Memory

 

[hgroth]

Here:

STAR TekInfo

They can also be tested using the 38 pin connector under the hood, using Mercedes STAR diagnostics. The OBD II connector only works for engine diagnostics. Everything else uses the 38 pin.

Jon

Here:

STAR TekInfo

They can also be tested using the 38 pin connector under the hood, using Mercedes STAR diagnostics. The OBD II connector only works for engine diagnostics. Everything else uses the 38 pin.

Jon

I just got a 38 pin to OBD2 adapter but I have not tried it. Maybe that will work

Try on Benzworld search W140 Forum "
Automatic Climate Control Diagnostic Trouble Code (DTC) Memory

That worked, thank you very much