PeachParts Mercedes-Benz Forum - ML320 Fan Problems

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ML320 Fan Problems

My '98 ML320 just had a problem with the "air circulator" tonight. On the way home from work the radio went very low and the air fan that pushes the air/heat into the cabin just gave up and won't come back on. Any way to give this a quick fix?

I get heat/air but no fan to blow the air into the cabin, so I freeze!

Quote:

Originally Posted by Ninety Eight ML (Post 1325097)

Should be an easy fix, new bower motor here http://www.trademotion.com/partlocator/index.cfm?action=getLocator&siteid=213951&chapter=EPI346&appSectionid=9&groupid=10074&subgroupid=601 40&make=67&model=Ml320&year=1998&catalogid=1 for $111.75 + shipping. Access motor from under passenger side of dash. ;)

That didn't fix the problem. Still no fan?

Fuse blown?

some thoughts on the blower motor circuit. you turn the switch to an on position. very low current at the switch. maybe an amp or two. this in turns activates a relay. the relay has high current capacity, say 30 amps. activating the relay provides the blower motor with the amps required to operate it. so far we have switch, relay and blower motor as suspects if the motor itself does not operate.

now on the blower motor wiring harness recall. if per chance mercedes engineers did not properly 'size' the circuit, underestimating the current draw of the motor, then the 30 amp fuse will blow. refitting a 40 amp harness is the recall fix. and substituting a 40 for the original 30 amp fuse. you cannot substitute a 40 amp fuse for the original 30 amp without upgrading the wiring harness.

so if the blower motor does not operate we have as suspects the #44 fuse, the switch, the relay and finally the motor itself.

you have replaced the motor. (or you could have bench tested the original motor.) so for the first go around we can eliminate the motor itself.

leaves us with the fuse/wiring harness, switch and relay as suspects.

my advice. check the #44 fuse. if it is blown then replace and see what happens. if it blows again, contact the dealer to see if they will perform the recall. if not, install the upgraded wiring harness yourself.

if the fuse is ok then the relay is suspect.

kind of a trial and error type dance.

hope this helps.

Quote:

Originally Posted by Ninety Eight ML (Post 1357147)

That didn't fix the problem. Still no fan?

Fuse blown?

Check 30a fuse #43 for the blower motor.

Quote:

Originally Posted by janko (Post 1357545)

now on the blower motor wiring harness recall. if per chance mercedes engineers did not properly 'size' the circuit, underestimating the current draw of the motor, then the 30 amp fuse will blow. refitting a 40 amp harness is the recall fix. and substituting a 40 for the original 30 amp fuse. you cannot substitute a 40 amp fuse for the original 30 amp without upgrading the wiring harness.

so if the blower motor does not operate we have as suspects the #44 fuse, the switch, the relay and finally the motor itself.

you have replaced the motor. (or you could have bench tested the original motor.) so for the first go around we can eliminate the motor itself.

leaves us with the fuse/wiring harness, switch and relay as suspects.

my advice. check the #44 fuse. if it is blown then replace and see what happens. if it blows again, contact the dealer to see if they will perform the recall. if not, install the upgraded wiring harness yourself.

if the fuse is ok then the relay is suspect.

kind of a trial and error type dance.

hope this helps.

please don't confuse the newbie, the blower motor under the passenger dash and the fuse#44 are two different things. fuse#44 related to the front a/c cooling fans (the twin ones sit in front of the radiator), the fuse can be blown if a/c is on and the wiring harness+fuse were not updated. however, the blower motor inside should still function. the poster should check the proper fuse number as listed inside the fuse box. The blower motor is linked to fuse #43 NOT 44, and I don't believe there is/was any TSB related to the blower motor fuse.

sorry. made a mistake. i confused the blower motor with the auxillary fan when i did my search. so we be looking at fuse #43. and nothing to do with a recall/tsb. thank you for correcting me.

I am the original owner of my 98 ML - wouldn't Mercedes send me a recall notice? Do you know where can I find the recall notice on the wiring harness related to the blower motor?