Mercedes-Benz Forum banner

1 - 5 of 5 Posts

·
Registered
1994 E420, 235K miles 8/2011, Original Owner, I do all of my own repairs, goal: how far can it go?
Joined
·
54 Posts
Discussion Starter #1 (Edited)
The a/c hasn't been cooling as it should after running for a while on a hot day. I hooked up the gauges to add some refrigerant. I noticed the aux fans were running intermittently. I unplugged the coolant sensor (on the top front of the engine) and the fans ran. Each time I would try to plug it back into the sensor, the fans would stop. I assume this means the sensor is bad and needs to be replaced? I think the part number is 0085-424-517

John
 

·
W124 Moderator
86 190E 2.3L 16V, 2 95 320TE's, 02 S500
Joined
·
12,756 Posts
If your AC system his charged correctly, the low speed fans will cycle as needed. Unplugging the sensor just kicks the fans to high speed. Under normal conditions, the high speed fans kick @ approx 105 degrees and turn off in the mid 90's.

Sent from my DROID2 using AutoGuide.Com Free App
 

·
Registered
1994 E420, 235K miles 8/2011, Original Owner, I do all of my own repairs, goal: how far can it go?
Joined
·
54 Posts
Discussion Starter #3
Jayare, I may have made the term "intermittently" sound too steady, the fans were actually coming on and going off very erratically like a poor wiring connection making or breaking contact. I have had the car for 19 years and this is not normal. I really think the sensor is going bad or a relay in the circuit going bad. We went out tonight with the connector unplugged and the fans running on full speed. The climate control worked much better than it has in the past few months.

Thanks for the input,
John
 

·
Registered
91 500SL 37k,90 300SE sold, 91 300E sold , 92 300E137k ,02 Kia Sedona ,I know..... its a Mini van.
Joined
·
8,143 Posts
Here were the symptoms of mine, car could be started cold and fans would kick in hi speed,then intermittently till completely warmed up,replaced 2 prong connecter, coolant sensor and all good,fans stopped doing the crazy erratic turn on!
think its around 26 bucks Autohausz AZ
 

·
Registered
1994 E420, 235K miles 8/2011, Original Owner, I do all of my own repairs, goal: how far can it go?
Joined
·
54 Posts
Discussion Starter #5
Here were the symptoms of mine, car could be started cold and fans would kick in hi speed,then intermittently till completely warmed up,replaced 2 prong connecter, coolant sensor and all good,fans stopped doing the crazy erratic turn on!
think its around 26 bucks Autohausz AZ
I will check out the connector. I replaced the upper wiring harness last year with a rebuilt harness from eBay that probably had an old connector on it. It could be the cause.

Thanks,
John
 
1 - 5 of 5 Posts
Top