http://www.peachparts.com/shopforum/tech-help/161249-help-97-e320-w210-aux-fan-not-working.html
I read this entire thread, and understand much of it. You are a real expert, and may have seen a set of issues like these. I am happy for pay for expertise. WDBJF65J52B454614 only 36K
My problem is similar except that instead of no aux fan operation, my aux fan howls as soon as the car is running.
History of problem:
1) no A/C
2) ran on board dx finding multiple A/C related sensor codes
3) replaced all sensors and cleared codes
Had the system evacuated and refilled showing 7 barr pressure without engine running.
Below is the history on this problem and my attempts to solve it:
I ran the on board diagnostics for sensors and fault codes as follows:
B1232 refrig pressure sensor
B1233 refrig temp sensor
B1227 outside temp sensor
B1231 engine coolant temp sensor
I replaced all 4 of these sensors and also the evaporator sensor (never had that code) but still have two codes that will not clear: B1227, never had incorrect readings on dash, and B1231, never had any overheating
Oddly after problem began I notice the night time illumination bulb in the HVAC is out and remains out even after replacing the bulb...
Sensor values are as car warm but not running as follows:
1 87 Inside car temp sensor
2 E Outside temp sensor (replaced)
3 87 Heater core L
4 87 Heater core R
5 89 Evaporator temp sensor (replaced) though it seemed normal
6 E ECT sensor (replaced) still shows E
7 07 bar refrig pressure sensor (replaced)
8 100 refrig temp sensor (replaced)
20 control current for aux fan 6.7
Compressor will not engage, has 7 bar pressure. Direct 12V to compressor and she blows cold. No blown fuses having anything to do with A/C, #5, #7, #20 or any in the fuse box by the brake booster. I swapped some fuses to be sure they were good. I found no direct compressor or clutch fuse in the box. Have not been able to find the function of relays in back of fuse box.
The engine cooling fan starting running all the time on high, probably because it thinks the car is overheating due to ECT sensor fault, so I unplugged fan. Located the Aux fan control unit under drivers headlight area, thought about changing it since its a known issue with these cars but never read this helping anyone with the fan howls only the fan won't engage issue.
Never any overheating. Checked the old ECT sensor in hot water with multimeter and it responds). I suspect this fault could also be the reason the compressor clutch will not engage.
When the problem began the EC light was on but I was able to get it to go off by changing the value of the computer by 16 points in an attempt to get the compressor started. It has not come back on since even after changing the value back to original.
Here is how I got the EC light to go out:
1. Switch the ignition on (position 2).
2. Set the left temperature to 'HI' and the right temperature to 'LO'.
3. Switch the ignition off.
4. While holding the 'REST' button, switch the ignition on (position 2). On the left side, 'P1' will flash and on the right side, a code will be displayed.
5. Press the 'EC' button twice so that the left side flashes 'P2'.
6. Using the right side red temperature increase button, add 16 to the value.
7. Press the 'EC button again to store the updated code.
8. Turn the ignition off.
I have since changed the value back to original settings.
Can you possibly help? I am very happy to pay for expertise.
We have no Mercedes Indy shops here in Maui Hawaii.
All the best,
Paul