Hello All,
Aux Fans Never come on.

From reading and what I've done so far.

Fuse 7 and D both good.

Checked X64/4 connector left of A/C drier getting 12 VDC there across the 2 pins. It looks like connector located here: http://catalog.worldpac.com/mercedesshop/sophio/wizard.jsp?partner=mercedesshop&clientid=catalog.mercedesshop&baseurl=http://catalog.peachparts.com/&cookieid=2CJ1CTPEN2CJ1DJY08&year=1992&make=MB&model=300-DT-003&category=G∂=Auxiliary+Fan+Assembly

I know the link only shows 1 fan. I have 2 fans M4m1 and M4m2 in the diagrams. Is the X64/4 connector the one shown in the above link.

Is it possible that both fans are shot. Both fans turn freely by hand. Maybe there another connector I'm not seeing by the fans.

Is it straight forward to remove the fans and test them. Any one know the ohms of the motors.

I get the fact that the fans are controlled by 2 different switches.
The Refrigerant High Pressure switch. Switch is normally open. Closes at 20 BAR activates the K10 Aux Fan Precompressor Relay. The Aux Fan Preressistor R15 (left hand side (drivers)behind head light) fan in low speed.

or

The B10/8 Coolant Temp Sensor, Operates the K9 Aux Fan relay. Fan runs in High speed.

I've read for the functional check: perform, by detaching and bridging plug on coolant temperature sensor or on the pressure switch for auxiliary fan, with ignition on.

No Joy.

Any suggestions?

Thanks.

__________________
92 300D 2.5L OM602 OBK #59

On the 1990 124.128 mind you...

YES, that's the plug!(In the little metal holder next to the Receiver/Drier)

I just went out and traced the wires from the plug...
(Pre-Catastrophe due diligence)
AND when I hook up 12volts to the
two pins (on the side that has it's wires dis-appear into the Radiator/
Condenser portion of the engine compartment) the fans spin!

On the side of the plugs towards the engine are identifying numbers and letters.

The Receiver plug (Female) is labeled: "W Germany" "9622/1"

The male plug (with two metal pins and one plastic alignment pin) is labeled:
with a trade mark of the letters LK [the K is resting on the horizontal portion of the L ]
inside a circle and the numerals 9602 to the right of the mark.

I did not power the fans any longer than necessary to prove that the plug
is their feed.(1 second)

So if you get fans spinning,from power to that plug...maybe it's the relay?
Good Luck ,let me know if I can try any thing else.

EDIT (I can Read,If I just slow down enough to comprehend)

I believe you told us that you have power to the female side of the X64/4
plug(...You have un-plugged the two halves and DMM'ed the female side
for voltage with one of SIXTO's two tests in action? Or WHAT?)

If that's true(you have voltage at the female side)I'm gonna pray for
a bad wire(s) between the fans and X64/4.The back side of the male
plug (LK 9602) has two black wires(Hot) and one brown(Ground).

Post on fan Bearing R+R:

file:///C:/Documents%20and%20Settings/Owner/My%20Documents/aux%20fan%20R+R.htm

Post on W124 Fans R+R:

file:///C:/Documents%20and%20Settings/Owner/My%20Documents/aux%20fan%20change.htm

When I put the DMM
(set to the upside-down horseshoe setting)
to the LK 9602 pins I get 1.0 (when it settles down).

__________________
'84 300SD sold
124.128

Apply power to the fans as comrpess ignite suggested. You can tap power from the glow plug relay if you're short of wire.

Then assuming MB didn't change things too much from the 1987 model...

Power for the fans come through relays K9 (high engine temp) and K10 (AC pressure switch). The fans get full voltage with high engine temp. Voltage goes through a 0.5ohm(?) resistor with AC pressure.

To check engine temp trigger operation, locate the 3-pin temp sensor at the engine end of the upper radiator hose. Remove the 2-pin connector and jump the contacts. The fans should go at full tilt. If not, suspect relay K9. I think relay K9 is in the right rear position in the relay box just aft of the fusebox.

To check the AC pressure trigger, disconnect the wires from the pressure switch with pigtails at the AC receiver/drier then jump the connectors (not the pigtails!). The fans should go at less tilt. If not, check for continuity through the resistor behind the left headlight. If that checks, suspect relay K10, it's the next one forward of K9.

Did you check the fuses? If you have no record of new fuses in the last 10 years, replace all of them!

Sixto
87 300D

Thanks for confirming the x64/4 connector. I read 12VDC there with the Analog Meter.

I've checked the fuses. I've actually pulled fuse D and lost voltage at the X64/4 connector.

hmmm.. Fans bummer... I'll double check the wiring today. I'll try to take some pictures. Any one know what the fans should Ohm out at?

__________________
92 300D 2.5L OM602 OBK #59

When I put the DMM
(set to the upside-down horseshoe setting)
to the LK 9602 pins I get 1.0 (when it settles down).

__________________
'84 300SD sold
124.128

Pulled fan assembly. WOW DEAD Bugs Galore. It doesn't have a way for the dead bugs to drop out.
Both fans shot.

__________________
92 300D 2.5L OM602 OBK #59

Isnt the aux fan fuse seperate from the fuse box? My 400E has one identical to the blower motor fuse. Its that funky 30A strip.

Perhaps its diff. on a diesel.

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93 300D 2.5 Turbo, Black/Palomino 273K
09 E350 Black/Black 41K

Yeap. Sure is. 2 different circuits. 2 separate fuses. Both fans run together. depending on what circuit will determine fan speed.

Picked up 2 fans at parts recycle center (junk yard) they come with a 30 day return policy ($40 each). The fans come on when (Red switch) is tripped. Took about 1 to install. The hard part is getting the lower horn support bolt in the back of the bumper.

All is good.

__________________
92 300D 2.5L OM602 OBK #59

Sorry about the financial hit.
But, You'll be cool sitting at those stoplights this summer!

__________________
'84 300SD sold
124.128

I'm OK. one fan is $140 ish. Next problem on list is Multifunction switch. Picked one up at the yard. It's tight and doesn't look too worn.

__________________
92 300D 2.5L OM602 OBK #59

Here is my thread on trying to trouble shoot the Aux fans on my 1990 2.5Turbo. How do you buy new MB relays, do you need to order them through a dealer or can you find them through fast lane?

What I did with pics:

http://www.peachparts.com/shopforum/diesel-discussion/252895-car-runs-hot-under-load-1990-w124-300d-2-5turbo-post2250006.html?posted=1#post2250006

__________________
1990 300D 2.5 Turbo 150k miles
1999 F250 7.3L Powerstroke 225k miles 22mpg
Intro Thread

I only replaced the fans. The switches/relays were fine.

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92 300D 2.5L OM602 OBK #59