YZ GREECE
07-12-2014, 01:26 PM
Hi all!
I own a late ’98, 202.018, M111.921, and have a problem with my a/c:
Clutch stays engaged for 2-3 minutes and then disengages. When engaged, I get ice cold air (as always). If I turn off engine wait a couple of minutes and then turn on again, it reengages and after 2-3 minutes goes off again. If the motor is hot (over 80-85c), it engages for 1 minute or not at all.
I did the following:
1. Ran the climate diagnostics
Current codes were 231, 232, 233 and stored ones were 416, 417, 419. Deleted them all but 231 still appeared. Deleted it 5-6 times more but it still appears.
No other code came up again (i run the test at least 3 times a day).
231 Engine Coolant Temperature Sensor (B11/4)
232 Refrigerant Pressure Sensor (B12)
233 Refrigerant Temperature Sensor (B12/1)
416 Coolant Circulation Pump (A31m1)
417 Left Duovalve (Water Valve) (Y21y1)
419 A/C Compressor Electromagnetic Clutch (A9k1)
2. Gone to an A/C mechanic
Refrigerant pressure, temp and quantity is ok (checked with diagnostics and also manually @ an a/c expert store – not specialized in MBs). He insisted on changing the coil (no charge if it was not the problem), so I changed it with a used one in good condition, but nothing happened.
He told me that ecu seems to be the problem
3. Tried to be a MB electrics expert
With the a/c “on” but clutch disengaged (after worked for some minutes), I sort wired the temp coolant sensor adapter and nothing happened (regarding clutch).
4. Asked FUPABOX his opinion
After a description I gave him, he said it may be the temp sensor (B11/4), the pressure sensor (B12) or maybe the ecu and suggested to try temp sensor first and pressure sensor then (thx a lot fupabox!).
5. Replaced Temp Sensor
I replaced the B11/4 and celebrated my compressor engagement for 4 continuous minutes.......
6. Gone to another A/C mechanic
Checked manually all systems/sensors/metrics etc and all seemed to be fine.
He told me it could be the ecu or something else.. he recommended to visit a Mb dealer or MB a/c expert (but i don’t want to pay a fortune...)
7. I use my common sense
I'm thinking on making a test before replacing going to an MB A/C expert or replacing myself the B12:
If I’m not mistaken, B12 is always "on" until pressure reaches high levels (eg >20 bars). So, if b12 has a problem, i can temporarily bypass it (for 6-7 minutes) by short wiring it (left and right contacts) - while the connector/adapter will be still connected to the sensor so i can get the metrics - to see if the clutch will stay engaged. I'm planning on watching the pressure metrics on climate control and immediately switch off engine if pressure goes too high (>19,00 / 19.50 bars).
(I asked Fupabox his opinion on this test… has not answered yet)
So i’ d like your opinion on the problem and the test i m going to run.
Thx a lot for reading this and i m looking forward to your answers!
I own a late ’98, 202.018, M111.921, and have a problem with my a/c:
Clutch stays engaged for 2-3 minutes and then disengages. When engaged, I get ice cold air (as always). If I turn off engine wait a couple of minutes and then turn on again, it reengages and after 2-3 minutes goes off again. If the motor is hot (over 80-85c), it engages for 1 minute or not at all.
I did the following:
1. Ran the climate diagnostics
Current codes were 231, 232, 233 and stored ones were 416, 417, 419. Deleted them all but 231 still appeared. Deleted it 5-6 times more but it still appears.
No other code came up again (i run the test at least 3 times a day).
231 Engine Coolant Temperature Sensor (B11/4)
232 Refrigerant Pressure Sensor (B12)
233 Refrigerant Temperature Sensor (B12/1)
416 Coolant Circulation Pump (A31m1)
417 Left Duovalve (Water Valve) (Y21y1)
419 A/C Compressor Electromagnetic Clutch (A9k1)
2. Gone to an A/C mechanic
Refrigerant pressure, temp and quantity is ok (checked with diagnostics and also manually @ an a/c expert store – not specialized in MBs). He insisted on changing the coil (no charge if it was not the problem), so I changed it with a used one in good condition, but nothing happened.
He told me that ecu seems to be the problem
3. Tried to be a MB electrics expert
With the a/c “on” but clutch disengaged (after worked for some minutes), I sort wired the temp coolant sensor adapter and nothing happened (regarding clutch).
4. Asked FUPABOX his opinion
After a description I gave him, he said it may be the temp sensor (B11/4), the pressure sensor (B12) or maybe the ecu and suggested to try temp sensor first and pressure sensor then (thx a lot fupabox!).
5. Replaced Temp Sensor
I replaced the B11/4 and celebrated my compressor engagement for 4 continuous minutes.......
6. Gone to another A/C mechanic
Checked manually all systems/sensors/metrics etc and all seemed to be fine.
He told me it could be the ecu or something else.. he recommended to visit a Mb dealer or MB a/c expert (but i don’t want to pay a fortune...)
7. I use my common sense
I'm thinking on making a test before replacing going to an MB A/C expert or replacing myself the B12:
If I’m not mistaken, B12 is always "on" until pressure reaches high levels (eg >20 bars). So, if b12 has a problem, i can temporarily bypass it (for 6-7 minutes) by short wiring it (left and right contacts) - while the connector/adapter will be still connected to the sensor so i can get the metrics - to see if the clutch will stay engaged. I'm planning on watching the pressure metrics on climate control and immediately switch off engine if pressure goes too high (>19,00 / 19.50 bars).
(I asked Fupabox his opinion on this test… has not answered yet)
So i’ d like your opinion on the problem and the test i m going to run.
Thx a lot for reading this and i m looking forward to your answers!