The auxiliary fan stop working on my 89 300e, I checked the fuse and it is OK, what is next?
Thanks, Rick.

http://catalog.eautopartscatalog.com/mercedesshop/sophio/wizard.jsp?partner=mercedesshop&clientid=mercedesshop&baseurl=http://catalog.peachparts.com/&cookieid=1CL0O6GWD1DP1DLME8&year=1989&make=MB&model=300-E-002&category=All&part=Engine+Temp.+Sensor
On top of the engine block. Try jumping this sensor. If fan comes on it needs replaced.

__________________
-Marty

1986 300E 220,000 miles+ transmission impossible
(Now waiting under a bridge in order to become one)

Reading your M103 duty cycle:
http://www.peachparts.com/shopforum/showpost.php?p=831799&postcount=13
http://www.peachparts.com/shopforum/showpost.php?p=831807&postcount=14

If the fan will not run when you directly apply 12 volts to it (bypassing all the switches and relays--it may be the brushes are not making contact with the armature. You CAN disassemble it, clean the armature, relube the bearings, and go for another 20 years. These fans are hell bent for stout, but for some reason the brushes will hang up or fail to make contact (the armature gets dirty from leaking bearing lube maybe?) I had one on which the 'foam' seal on the front under the flan blade dissolved/crumbled and jammed the bearig. Cleaned things out (was 10 years old down here in the hell city of Houston and looked like new inside), replaced foam seal with one cut from christmas decoration felt, regreased bearing, went another 10 years fine.

You've already checked the fuse, that's always the first thing.

Jumping the switch on the thermostat housing doesn't prove an a/c fault at that switch should only work at ~105degC and will turn the fan on full speed,not low speed which is what the a/c turns on.

Is your A/C cold when driving? If it isn't then you may not have enough gas in the system to trip the pressure switch to turn the fans on. The fans shouldn't run all the time when the a/c is on.

I think your model has 2 speed fans. Check the fuse in the relay for the aux fans. Also check the balast resistor for the aux fans, they burn out eventually.

Get back to us with what you find.

__________________
Alex.

MB Tech
Sydney, Australia
Volvo 122S
W201 190D 2.5 manual
W202 C240
W203 C32

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Thanks so much,I'll try to do what you told me, but I'm not sure how to bridge the temperature sensor. Which of the three poles I have to bridge?
Can I bridge the balast resistor to check if it works?
Thanks , Rick.




QUOTE=AusMBtech]You've already checked the fuse, that's always the first thing.

Jumping the switch on the thermostat housing doesn't prove an a/c fault at that switch should only work at ~105degC and will turn the fan on full speed,not low speed which is what the a/c turns on.

Is your A/C cold when driving? If it isn't then you may not have enough gas in the system to trip the pressure switch to turn the fans on. The fans shouldn't run all the time when the a/c is on.

I think your model has 2 speed fans. Check the fuse in the relay for the aux fans. Also check the balast resistor for the aux fans, they burn out eventually.

Get back to us with what you find.[/QUOTE]