Morning all,

Have not seen any posts in this regard, so here it goes.
I have a 93 300D 2.5 Turbo (W124) that normally has a water temp between 83 to 86 deg C (under climbing conditions it sometimes gets close to 90 deg).

But when I turn on the AC, within 3-5 min it quickly climbs to 90 then if I sit still it get close to 100. If I continue on in stop go traffic it stays at this and sometimes has closely approached 120. I have not head nor observed the fans kick in at any time, but not been familiar as to at what temperature they kick it makes it hard to conjecture if they are the problem or not.

I would appreciate some of the experts to give some input as if I have: Fan, water pump or radiator issues here. I would be inclined to say water pump or radiator, but that is just my educated guess.

Thanks in advance for the help.

Adriano

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Adriano

83 300SD 500,300 miles (Well seasoned work horse AKA "Put Put")
93 300D 245,000 miles (Moms Baby AKA "Sweat Pea")
87 300D 185,000 miles (Life giver, aka parts car for my 300SD)

check your fender behind driver's headlight. look at the big honking resistor there. get a jumper and jumper around the resistor and see if your fans now work.
you also might wanna verify your fan clutch is working. mine had a damaged wire on the resistor, and no power was making it to the fans.

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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

My W124 did that and after replacing the fan clutch the temperature stays normal. Both of my electric fans where working at the time too.

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1993 W124 300D 2.5L Turbo, OM602.962
2000 Chevrolet Cavalier, 2.4L DOHC
2002 Ford Explorer, 4.0L SOHC
2005 Toyota Prius, 1.5L

http://www.fuelly.com/sig-us/40601.png

I had the exact same issues and replaced my fan clutch. very easy to to myself and it fixed the overheating issues. i payed $60 for my fan clutch from ebay. worked great. I have not tested my fans yet.

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Grey '91 350SDL 214k Dad's car
Beige '81 240D 4 Speed 254k SOLD
Blue '82 300D 225k SOLD
White '95 E300D 46k SOLD
Blue '87 190D 2.5 Turbo 315k SOLD
Brown '80 240D 4 Speed 716k SOLD
Beige '80 300D N/A 119k SOLD
Blue '85 300D Model 186k T-Boned

Thanks guys,

Ordering a fan clutch......but for my learning experience why would it show up with the AC on and not otherwise?

Thanks,

Adriano

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Adriano

83 300SD 500,300 miles (Well seasoned work horse AKA "Put Put")
93 300D 245,000 miles (Moms Baby AKA "Sweat Pea")
87 300D 185,000 miles (Life giver, aka parts car for my 300SD)

When you run the ac it loads the engine more, and then you also have the condenser on the front of the car expelling a lot of heat, making the air going into the radiator less cool.

-J

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1991 350SDL. 230,000 miles (new motor @ 150,000). Blown head gasket

Tesla Model 3. 205,000 miles. Been to 48 states!
Past: A fleet of VW TDIs.... including a V10,a Dieselgate Passat, and 2 ECOdiesels.
2014 Cadillac ELR
2013 Fiat 500E.

With a load and the A/C running mine will get up to 100c on a hot 95F+ day. It cools right down if the A/C is off. Hasn't gotten much above 100c. Otherwise with out the A/C on it runs about 80c.

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92 300D 2.5L OM602 OBK #59

OK,

While awaiting for new fan clutch decided to test-out the auxiliary fans. I located the "honking" resistor pointed out by VSTECH, checked volts before and after 0V!

Traced the wires and saw a cable coming out from under the right (as you face the car front) lower side to a plug just to the lower left of the big honking resistor. Unplugged the plug and ohmmed to the resistor and verified this is the wire. I then proceeded to apply direct 12V to the wire.....still no fan turning. Ohmmed across the plug and did not get any resistance reading PERIOD!

What is the wiring doing behind the plastic shroud of the fans? Is there a termistor or other device behind there?

Can someone please send me the wiring diagram for the auxiliary fan supply?

Many thanks in advance.

Adriano
P.S. just in case someone asks again it is a 93 300D 2.5 Turbo diesel

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Adriano

83 300SD 500,300 miles (Well seasoned work horse AKA "Put Put")
93 300D 245,000 miles (Moms Baby AKA "Sweat Pea")
87 300D 185,000 miles (Life giver, aka parts car for my 300SD)

on mine, power brings the fans right on. my resistor was toast, I bypassed it, and the fans came right on. lemme know if you need a set of fans.

__________________
John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

Hi VSTECH,


Looks as if my fans may be toast. I bypassed the resistor....no turning. Unplugged the connector leading to the plastic bezel just under the lower right side of the fans and applied 12V directly to that point....no turning. Ohmmed the connector and found it to have almost infinite resistance (open), so if there is no thermistor or some type of temperature sensing circuit in line with fans, it appears my fans are toasted. How much for the ones you offered?

Many thanks to all,

Adriano

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Adriano

83 300SD 500,300 miles (Well seasoned work horse AKA "Put Put")
93 300D 245,000 miles (Moms Baby AKA "Sweat Pea")
87 300D 185,000 miles (Life giver, aka parts car for my 300SD)

If you do a search here on the forums there is a procedure for rebuilding them.
It's here: http://www.peachparts.com/shopforum/showthread.php?t=278850&highlight=fan+bearings

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92 300D 2.5L OM602 OBK #59