[DecoThom]

SL AC Troubleshooting

AC Off light kills AC operation. Codes B1000-001 B1256-001 Malfunction in refrigerant circuit HOW DO I FIX? or Faulty Control Unit

How do I fix a malfunction in refrigerant circuit or faulty control unit indicated by AC codes?

Is there a sensor to replace? A short to fix, oil in a connector, a bad connection, anything simple? Is there a troubleshooting guide, circuit diagram, diagram of AC (Air Conditioning) components, something useful?

The AC works perfectly until the AC Off light comes back on. The refrigerant level is measured - optimal.

When I erase codes with My Autel Diaglink, the AC Off light turns off; and the AC works perfectly. After I turn the car off and on a few times, the AC Off light comes back on; the AC quits blowing cold; and I read the following codes:

B1000-001 Stored
The control unit is faulty.
B1256-001 Stored
Malfunction in refrigerant circuit

From my signature, see this is a 2003 SL500 USA model.


Thanks in advance guys!
Thom

 

[bobterry99]

I would use a diagnostic tool and see what the control unit is reading for refrigerant pressure and evaporator temperature and judge whether the readings are plausible.

 

[rudeney]

B1000 may be the real culprit as it indicates that the control unit (the dash panel controls for the ACC) is defective. B1256 is either low refrigerant in the system, or a defective temp/pressure sensor on the evaporator. SDS can test that component. If it's bad, it will require opening the refrigerant system, so it will have to be full recharged.

 

[DecoThom]

B1000 may be the real culprit as it indicates that the control unit (the dash panel controls for the ACC) is defective. B1256 is either low refrigerant in the system, or a defective temp/pressure sensor on the evaporator. SDS can test that component. If it's bad, it will require opening the refrigerant system, so it will have to be full recharged.

Thanks Rudeney,

That is excellent analysis of my codes. Is there an AC component diagram? I would like to clean the connector to the temp/pressure sensor on the evaporator.

 

[rudeney]

I think it's going to be difficult to access:

 

[DecoThom]

great picture of the sensor... thanks. I used my Diaglink to clear the AC system DTCs (Diagnostic Trouble Codes) another time or 2 or 3; and the AC is working properly again. This is my first summer owning the R230.