Car : '83 CD turbo

Problem: Every 3rd day or so fuse #14 (8 amp white) blows. I even threw in a blue 16 amp and that went also.

From fuse cover panel this fuse covers:
Back up lamp
Warning Monitor term. 8
emission control
horn
switch-over valve overload protection device
relay auxiliary fan term. 86
control unit/water pump/heating water valve for climate control system, (automatic transmission)

First thought is that this has something to do with the Auxiliary fan because it does not turn on when the AC is on all the time (i have only heard it run twice in the month i have owned the car)

I tested the relay with a 12v source and it clicks and the continuity switches like it is supposed to. Even switched the two silver relays to see if the same happened with both and still does.

The aux fan works with 12v directly to it.

I tried to short the switches on the AC drier thing in the passenger side fender behind the headlight, but that did not switch on the aux fan (with AC running).

Should i run a manual switch to the aux fan and remove the silver relay on the drivers side fender (the one closer to the fuse box).. ?

Anyone else had symptoms like this?

Thanks!

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'87 300D new to me
'85 300D Sold
'83 300cd Sold

I don't know if this is related but if i have my A/C on and i accelerate at least 10-15mph then the A/C blows hot air and i have to switch it off and back on again..

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'87 300D new to me
'85 300D Sold
'83 300cd Sold

Just as a test, try disconnecting the electrical connector from the transmission kickdown switch (under the accelerator pedal) and see if that stops the fuse from blowing. My 1984 300TD was randomly blowing the #14 fuse and after a lot of troubleshooting I figured out that the reference to "automatic transmission" on the cover had to be the kickdown solenoid. My kickdown solenoid was bad and every time that I floored the accelerator and it hit the kickdown switch, the fuse blew.

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1984 MB 300TD
2003 Subaru WRX

Try turning the aux fan by hand and see if u feel any roughness in the bearings, I had the same problem where the fuse would blow any time the fan came on. It turned out to be the bearing in front of the fan, it was rusted and preventing the fan from turning freely and thus the higher current draw would blow the fuse, if thats the problem the don't blow $150 on a new fan just buy the bearing mine cost $8 and replace it. My car has 244k with the original fan and the brushes on the fan still had about 1 inch of "meat" in them.
It can also turn out that you have a problem on a diff circuit that's covered by the same fuse. Do the fan first and thats one less circuit to diagnose.

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87 300d Turbo 241K with original #14 head (blue)
87 300d Turbo 198K will run great again someday (silver)
84 300sd sold ( buyer drove it to Paraguay )

I'll have to check out the kickdown switch..

As for the aux fan, i hooked it up to a 12v power source and ran a multimeter in line to test the amps.. it pulled out right below 8 amps (7.8+) and their isn't much resistance when i spin it by hand... but something must be preventing it to turn on with the AC.. it should turn on right?

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'87 300D new to me
'85 300D Sold
'83 300cd Sold

I had that problem, and spent a lot of time looking for the cause.
Put in the correct fuse, and hit the horn button.
If it blows the fuse, look under the front the car and see if the one of the horn wires are shorted to ground.
I must have gotten to close to one of those parking lot stops and bent upward the splash pan slightly.
I straightened the pan and rotated the horn.

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1985 300D California w/cat. (257,000 + Miles)
1980 300SD (208,000 + Miles)

i just blew the #14 fuse as well. bad connection at the monovalve. you could try to check that as well. take apart the plug and clean the connections and squeeze them tight again with needle nose pliers. so far it's holding after doing that.

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1984 300D Turbo - 231k....totalled 11/30/07 RIP

I'd have to check my schematic but I think that is the same fuse that blows when the kickdown switch is shorted. The wire leading to the transmission wore through near the transmission mount. Just wrap some electrical tape around it.

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84 300DT Puke Yellow. Totalled after 438,000
84 300DT Orient Red. 169,000 (actual mileage may vary)
2002 Explorer EB (wife's)

You guys are good. It was the kickdown switch. I was cruising along the highway and floored it and as soon as it downshifted the tach died, along with the horn.

I'll have to next check the solenoid and the wire and see what's causing the troubles.


Thanks again!

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'87 300D new to me
'85 300D Sold
'83 300cd Sold

Get up under that transmission and you are likely to see the wire. Suprisingly it isn't very protected. I did a half a**ed job to repair it on the old 300D (orange wire nut ) and it worked until I totaled the car.

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84 300DT Puke Yellow. Totalled after 438,000
84 300DT Orient Red. 169,000 (actual mileage may vary)
2002 Explorer EB (wife's)