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I have a 2003 ML350 VIN number 4JGAB57E63A405447. My AC is intermittently quitting and blowing hot air. I have been keeping an eye on it with my scanner and when it happens I am getting the code B1 2/2 (Refrigerant pressure and temperature sensor). When I drill into the actual AC control module information, I am getting 10 bars of pressure on B1 2/2 and INVALID for what I assume is the temperature. I do not know if the AC is low of refrigerant or not. This only happens when it is warm outside; the sensor functions normally during colder weather and does not report INVALID. When this happens, the AC compressor is reported running at 0%, and I can confirm it isn't running because both AC lines are warm. I have attached some screenshots of my scanner.
EDIT: Realized I had the wrong thread title
My plan was to have the AC system evacuated, replace the sensor, then have the AC system refilled. Is there anything I can check to make sure it is the sensor before pulling the trigger on this? Any input will be greatly appreciated.
Hi Maj. Dundee. When I request A/C it looks like my cooling fans are not coming on. I have noticed a screeching noise from the cooling fans when they do come on, but I haven't heard it recently. I tried turning on the AC on full blast, pressing the AC button on and off, and I wasn't able to get them to come on. Should I be replacing these first? Thank you for the help.
Looks like the temp sensor was the fix. I had a shop reclaim the refrigerant and then I replaced the sensor and recharged it. It is working now and not throwing that code. If someone else is going to do this job, I was able to get to the sensor by pulling out both headlights and the cross brace over the radiator and getting at the sensor with a smaller crescent wrench. I didn't have to pull out the windshield wiper fluid reservoir like others.
Maj. Dundee, I haven't see the aux fans come on again anytime recently. Should I probe the wiring harness with a multimeter to see if there is voltage or what is the recommended procedure for that? I am thinking the fan motors are cooked because they have been making a squealing noise for a long time now and may have just given out.
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