Coolant visit workshop
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Joined: Jul 2018
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MBZ E350 Convertable
Coolant visit workshop
MBZ C350 Convertable Vin 6T062619
HOT weather 104+ never had problem before heat wave in So Cal. I checked coolant level cold and hot and both times the resv was full. The light seemed to turn off then back on . And the AC would turn off when light came on. First thing in the morning warning was not on until I drove for a while. Is it coolant level sensor, or float level sensor, or worse? I do not recall hearing any electric fan, maybe it does not have an electric fan
HOT weather 104+ never had problem before heat wave in So Cal. I checked coolant level cold and hot and both times the resv was full. The light seemed to turn off then back on . And the AC would turn off when light came on. First thing in the morning warning was not on until I drove for a while. Is it coolant level sensor, or float level sensor, or worse? I do not recall hearing any electric fan, maybe it does not have an electric fan
Super Member
Joined: Jul 2009
Posts: 938
Likes: 53
From: Montreal, Canada
2005 C240 2011 R350
I had similar problems Both the collant level and the windshield washer level sensors are in series. They have magnetic reed switches activated by magnet in the float.
I got collant warnings for long time.. came and went.. then also windshield washer level warnings...But I never had any overheating or AC issues...For me it clearly was only faulty sensor. Both sensor have a resistor in parallel with a reed switch activated by a magnet on the float mechanism.. I forgot which was which but one was around 100ohms, the other around 180ohms.. So under normal conditions the SAM reads 280 Ohms... if the collant trips then its resistor is shorted by the read switch... and vice versa for the washer fluid thus lowering the resistance. Both are easy to replace... the collant sensor is just remove the connector and twist out the sensor...
For the washer fluid you have to drop the lower pan and remove wheel well plastic to get to the sensor.. Just pry it out of the grommet.
What I did was replace both sensors with resistors (small ones fit directly into the connector) i would show pics but I got my phone wet so all is lost.
I will order new parts next time i place parts orders...
I got collant warnings for long time.. came and went.. then also windshield washer level warnings...But I never had any overheating or AC issues...For me it clearly was only faulty sensor. Both sensor have a resistor in parallel with a reed switch activated by a magnet on the float mechanism.. I forgot which was which but one was around 100ohms, the other around 180ohms.. So under normal conditions the SAM reads 280 Ohms... if the collant trips then its resistor is shorted by the read switch... and vice versa for the washer fluid thus lowering the resistance. Both are easy to replace... the collant sensor is just remove the connector and twist out the sensor...
For the washer fluid you have to drop the lower pan and remove wheel well plastic to get to the sensor.. Just pry it out of the grommet.
What I did was replace both sensors with resistors (small ones fit directly into the connector) i would show pics but I got my phone wet so all is lost.
I will order new parts next time i place parts orders...
